29 Jun
2008
29 Jun
'08
3:47 p.m.
I'm sure most everyone who has ever used a C64 is aware of just how
phenomenally bad the Commodore power supply is. I have only one C64,
but both of my spare Commodore power supplies have now failed, taking
a few 4164 RAM chips with them (thankfully, I have replacements!).
Does anyone know of a commercially available replacement power supply,
before I go off and build one? A linear supply would be trivial to
design, but I've never done a switching power supply, which I suppose
would be greatly preferable. The trick with the C64 is that it
requires both 9V AC and +5V DC. (I've considered frankensteining
together 9V AC and +5V DC wall-wart adapters onto the same DIN-7
cable, but it just feels so very very wrong).
I'd love to hear from other Commie fans who've solved the power problem.
-Seth
29 Jun
29 Jun
4:21 p.m.
On Sunday 29 June 2008 18:47, Seth Morabito wrote:
I'm sure most everyone who has ever used a C64 is
aware of just how
phenomenally bad the Commodore power supply is.
Oh yeah! We used to fix them, and selling aftermarket supplies was a
nontrivial portion of our business. :-)
I have only one C64, but both of my spare Commodore
power supplies have now
failed, taking a few 4164 RAM chips with them (thankfully, I have
replacements!).
I have a fair amount of those, too. As well as lots of other parts, both NOS
and salvage. I wouldn't even recommend using the factory-supplied supply,
or at least not one of the "brick" types that are potted. The real early
ones that were vented aren't quite as bad.
Does anyone know of a commercially available
replacement power supply,
before I go off and build one?
I know there used to be a bunch of them out there. The one that we sold the
most of was called a "CPS-10" but I can't recall who made it offhand. We
bought 'em from a distributor called Allegro Tech in MA, but I don't think
that's who made them, though I'm not sure.
A linear supply would be trivial to design, but
I've never done a switching
power supply, which I suppose would be greatly preferable.
Not really, for the smallish load we're talking here -- 5V @ 1A and 9VAC also
@ 1A. Total of 14 watts, building a switcher hardly seems worth it.
The trick with the C64 is that it requires both 9V AC
and +5V DC. (I've
considered frankensteining together 9V AC and +5V DC wall-wart adapters onto
the same DIN-7 cable, but it just feels so very very wrong).
To build a small linear supply the trickiest part is going to be finding an
appropriate power transformer that'll support both of those outputs. It may
just be easiest to use two separate smallish transformers and wire the
primary windings together.
I'd love to hear from other Commie fans who've
solved the power problem.
See above. :-)
--
Member of the toughest, meanest, deadliest, most unrelenting -- and
ablest -- form of life in this section of space, ?a critter that can
be killed but can't be tamed. ?--Robert A. Heinlein, "The Puppet Masters"
-
Information is more dangerous than cannon to a society ruled by lies. --James
M Dakin
7:19 p.m.
At 7:21 PM -0400 6/29/08, Roy J. Tellason wrote:
I know there used to be a bunch of them out there. The
one that we sold the
most of was called a "CPS-10" but I can't recall who made it offhand. We
bought 'em from a distributor called Allegro Tech in MA, but I don't think
that's who made them, though I'm not sure.
I bought one of these last year thanks to Roy's suggestion. It is a
Phoenix CPS-10 from Phoenix Electronics Inc. of Clay Center, KS. I
got mine off of eBay, and it wasn't cheap, I think I paid about $60
for it.
Of course a couple days later I lucked out and was given a C-128
powersupply of similar construction that appears to have been
modified to also run a +4. I still need to check the pin-out on the
power supply, but it seems likely given the number of +4's included
with the C128.
Zane
--
| Zane H. Healy | UNIX Systems Administrator |
| healyzh at aracnet.com (primary) | OpenVMS Enthusiast |
| MONK::HEALYZH (DECnet) | Classic Computer Collector |
+----------------------------------+----------------------------+
| Empire of the Petal Throne and Traveller Role Playing, |
| PDP-10 Emulation and Zane's Computer Museum. |
| http://www.aracnet.com/~healyzh/ |
5:08 p.m.
Seth Morabito wrote:
Does anyone know of a commercially available
replacement power supply,
before I go off and build one? A linear supply would be trivial to
design, but I've never done a switching power supply, which I suppose
would be greatly preferable. The trick with the C64 is that it
requires both 9V AC and +5V DC. (I've considered frankensteining
together 9V AC and +5V DC wall-wart adapters onto the same DIN-7
cable, but it just feels so very very wrong).
Sounds like you just need a single 9VAC power supply, a bridge, a
voltage regulator, and perhaps some caps to clean up the signal a bit.
The trick is to provide enough wattage.
5:26 p.m.
On Sunday 29 June 2008 20:08, Ray Arachelian wrote:
Seth Morabito wrote:
No.
The 9VAC has to be a separate transformer winding from the one that provides
the +5VDC eventually, because of how it's used...
One thought that came to me after my previous response was posted is that if
one happens to have a really trashed 1541, that transformer could be used,
as well. In fact, I built a bench supply that worked that way, though my
attempts to try and run two 64s off it at the same time never worked, even
though I had separate regulators for the two outputs. Too much interfence
between the two. Any time I'd hook two computers up and turn 'em both on the
output voltage on both would drop way down, and my scope showed me some
seriously bad oscillations going on. I suppose these days I know a bit more
about how to treat those 3-terminal regulators, but I've never bothered to
modify the thing...
--
Member of the toughest, meanest, deadliest, most unrelenting -- and
ablest -- form of life in this section of space, ?a critter that can
be killed but can't be tamed. ?--Robert A. Heinlein, "The Puppet Masters"
-
Information is more dangerous than cannon to a society ruled by lies. --James
M Dakin
Does anyone know of a commercially available
replacement power supply,
before I go off and build one? A linear supply would be trivial to
design, but I've never done a switching power supply, which I suppose
would be greatly preferable. The trick with the C64 is that it
requires both 9V AC and +5V DC. (I've considered frankensteining
together 9V AC and +5V DC wall-wart adapters onto the same DIN-7
cable, but it just feels so very very wrong).
Sounds like you just need a single 9VAC power supply, a bridge, a
voltage regulator, and perhaps some caps to clean up the signal a bit.
The trick is to provide enough wattage. 
6:27 p.m.
Sounds like
you just need a single 9VAC power supply, a bridge, a
voltage regulator, and perhaps some caps to clean up the signal a bit.
The trick is to provide enough wattage.
No.
The 9VAC has to be a separate transformer winding from the one that provi=
des=20
the +5VDC eventually, because of how it's used...
30 Jun
30 Jun
12:56 p.m.
On Sun, Jun 29, 2008 at 6:27 PM, Tony Duell <ard at p850ug1.demon.co.uk> wrote:
What about a transformer with 2 separate 9V secondary windings (not hard
to find)? Use one for the 9V AC, the other to feed the 5V
rectifier/regulator circuit.
This seems like the best idea, to me. I'm not any kind of electronics
wizard, but a power supply circuit driven from a transformer with two
secondary windings is something I'd be comfortable designing.
Thank you very much for the tips, everyone.
-Seth
Sounds like you just need a single 9VAC power supply,
a bridge, a
voltage regulator, and perhaps some caps to clean up the signal a bit.
The trick is to provide enough wattage.
No.
The 9VAC has to be a separate transformer winding from the one that provi=
des=20
the +5VDC eventually, because of how it's used...
1:05 p.m.
On Monday 30 June 2008 15:56, Seth Morabito wrote:
On Sun, Jun 29, 2008 at 6:27 PM, Tony Duell <ard at
p850ug1.demon.co.uk> wrote:
What about a transformer with 2 separate 9V secondary windings (not hard
to find)? Use one for the 9V AC, the other to feed the 5V
rectifier/regulator circuit.
This seems like the best idea, to me.
Agreed! :-)
--
Member of the toughest, meanest, deadliest, most unrelenting -- and
ablest -- form of life in this section of space, ?a critter that can
be killed but can't be tamed. ?--Robert A. Heinlein, "The Puppet Masters"
-
Information is more dangerous than cannon to a society ruled by lies. --James
M Dakin
Sounds like you just need a single 9VAC power supply,
a bridge, a
voltage regulator, and perhaps some caps to clean up the signal a bit.
The trick is to provide enough wattage.
No.
The 9VAC has to be a separate transformer winding from the one that
provi= des=20
the +5VDC eventually, because of how it's used... 
5:39 p.m.
How much effort you want to go through depends upon how much you value
what you are powering. The cheapest solution is to go to a flea
market a find a power supply.
Dual secondary windings is a good idea, but it's not that much savings
over two transformers. I wouldn't use a non-switching regulator for
the 5VDC, unless you need to warm your house. I'd get a switching
28V->5V 10 to 20W isolated DC/DC converter for the DC portion. But in
any case, this supply is going to cost more that two wall warts would
and, depending upon how skillful you are at building it, it may not be
any safer or more reliable.
I guess a question is, what fraction of a typical machine's value
should you spend on protecting it from its power supply? For rare and
valuable machines, should we be building supplies with dual switching
converters with 6kV isolation, diode mixed with over-voltage and
over-current protection and a soft start circuit? Or is a $50-$100
regulated bench supply for each voltage good enough? I worry about
this every time I turn some machines on....
Eric
5:59 p.m.
On Monday 30 June 2008 20:39, Eric J Korpela wrote:
How much effort you want to go through depends upon
how much you value
what you are powering. The cheapest solution is to go to a flea
market a find a power supply.
Dual secondary windings is a good idea, but it's not that much savings
over two transformers.
It'll likely be a savings in space, but also may end uip costing more.
I wouldn't use a non-switching regulator for the
5VDC, unless you need to
warm your house. I'd get a switching 28V->5V 10 to 20W isolated DC/DC
converter for the DC portion. But in any case, this supply is going to cost
more that two wall warts would and, depending upon how skillful you are at
building it, it may not be any safer or more reliable.
I guess a question is, what fraction of a typical machine's value
should you spend on protecting it from its power supply? For rare and
valuable machines, should we be building supplies with dual switching
converters with 6kV isolation, diode mixed with over-voltage and
over-current protection and a soft start circuit? Or is a $50-$100
regulated bench supply for each voltage good enough? I worry about
this every time I turn some machines on....
A switcher isn't necessarily going to provide more in the way of protection.
If one is worried about what the supply might do to equipment in terms of
overvoltage the simplest solution is to put a crowbar at the output of it,
along with an appropriate fuse. If anyone doesn't know how to make one of
these I can describe it pretty simply, just let me know...
--
Member of the toughest, meanest, deadliest, most unrelenting -- and
ablest -- form of life in this section of space, ?a critter that can
be killed but can't be tamed. ?--Robert A. Heinlein, "The Puppet Masters"
-
Information is more dangerous than cannon to a society ruled by lies. --James
M Dakin
5:42 p.m.
On Monday 30 June 2008 16:19, Eric Smith wrote:
Roy wrote:
The 9VAC supply is fed into a voltage doubler to derive the regulated +12V and
a separate +5VDC supply, and I don't think that either of those 9VAC lines
can be grounded. I have some fairly complete schematics around here
someplace, but I'd have to find 'em to be able to explain it in more detail
than that.
If you have a schematic of the C64 available, try envisioning what would
happen if you grounded either of those 9VAC lines, as in what components
would end up shorted out. :-)
--
Member of the toughest, meanest, deadliest, most unrelenting -- and
ablest -- form of life in this section of space, ?a critter that can
be killed but can't be tamed. ?--Robert A. Heinlein, "The Puppet Masters"
-
Information is more dangerous than cannon to a society ruled by lies. --James
M Dakin
The 9VAC has to be a separate transformer winding
from the one that
provides the +5VDC eventually, because of how it's used...
Why does it require isolation between the 9VAC and the +5V DC? It's not
obvious to me from the schematic. 
5:52 p.m.
I wote:
Why does it require isolation between the 9VAC and the
+5V DC? It's not
obvious to me from the schematic.
Roy wrote:
The 9VAC supply is fed into a voltage doubler to
derive the regulated +12V
and a separate +5VDC supply, and I don't think that either of those 9VAC
lines can be grounded.
Neither side needs to be grounded.
The C64 *already* has a bridge rectifier and 5V linear regulator powered
by the 9VAC input to produce an auxiliary 5V supply, so I don't see why
building an external power supply using a transformer with a single 9VAC
secondary, and a bridge rectifier and 5V regulator (linear or switching)
would be a problem.
However, I haven't tried it, and don't accept any responsibility for
anyone else trying it.
Eric
6:02 p.m.
On Monday 30 June 2008 20:52, Eric Smith wrote:
I wote:
Well, if you were trying to operate the 9VAC and the regulator for the +5VDC
off the same winding, you'd run into some trouble there, I think...
Why does it require isolation between the 9VAC
and the +5V DC? It's not
obvious to me from the schematic.
Roy wrote:
The 9VAC supply is fed into a voltage doubler to
derive the regulated
+12V and a separate +5VDC supply, and I don't think that either of those
9VAC lines can be grounded.
Neither side needs to be grounded. The C64 *already* has a bridge rectifier and 5V linear
regulator powered
by the 9VAC input to produce an auxiliary 5V supply, so I don't see why
building an external power supply using a transformer with a single 9VAC
secondary, and a bridge rectifier and 5V regulator (linear or switching)
would be a problem.
Because they really need to have those two +5VDC supplies separate and
independent of each other. That's the way the thing was designed, and as
much as that company was into cost-cutting and shaving wherever they could,
to the extent possible, I think that if they could have omitted that somehow
they would have.
However, I haven't tried it, and don't accept
any responsibility for
anyone else trying it.
:-)
--
Member of the toughest, meanest, deadliest, most unrelenting -- and
ablest -- form of life in this section of space, ?a critter that can
be killed but can't be tamed. ?--Robert A. Heinlein, "The Puppet Masters"
-
Information is more dangerous than cannon to a society ruled by lies. --James
M Dakin
6:13 p.m.
Roy wrote:
Because they really need to have those two +5VDC
supplies separate and
independent of each other.
They aren't independent. They share a common ground reference.
The fact that the internal regulated +5VDC supply shares a common ground
with the external +5VDC supply but is derived from the 9VAC supply
demonstrates that there's no difficulty with deriving an external
ground-referenced +5VDC supply from the same 9VAC, provided that there's
enough current available from that 9VAC source.
Eric
6:24 p.m.
On Monday 30 June 2008 21:13, Eric Smith wrote:
Roy wrote:
How would logic levels work otherwise?
They're independent, though, in the sense that loads on one will not affect
the regulation of the other.
--
Member of the toughest, meanest, deadliest, most unrelenting -- and
ablest -- form of life in this section of space, ?a critter that can
be killed but can't be tamed. ?--Robert A. Heinlein, "The Puppet Masters"
-
Information is more dangerous than cannon to a society ruled by lies. --James
M Dakin
Because they really need to have those two +5VDC
supplies separate and
independent of each other.
They aren't independent. They share a common ground reference.
6:47 p.m.
I wrote:
They aren't independent. They share a common
ground reference.
Roy wrote:
They're independent, though, in the sense that
loads on one will not
affect the regulation of the other.
Ever heard of ground bounce? Calling one side of the supply "ground"
doesn't exempt it from Maxwell's equations. The fact that the +5V rails
are separate doesn't completely prevent noise from coupling between
the two, because there are signals crossing between the domains.
The point I was making wasn't that it isn't a good idea to avoid noise
coupling between the two +5V supplies, but that the machine isn't going
to burst into flames if the external +5VDC is derived from the same
transformer winding. There are various ways of reducing noise
coupling between two DC power supplies without requiring separate
windings. In practice, I expect that simply having reasonable
filter caps on the 5V regulator would be sufficient.
Eric
7:54 p.m.
On Monday 30 June 2008 21:13, Eric Smith wrote:
How would logic levels work otherwise?
They're independent, though, in the sense that loads on one will not af=
fect=20
the regulation of the other.
Am I missing something here of have Commodore managed to make a ground
trace with no inductance (in violation of the laws of physics)?
One of Vonada's laws is 'There is no such thing as ground'. It's not at
all un common for there to be significant ripple on a ground connection
(measures wrt some other point on the _same_ trace!) doe to the
inductance of said trance. And it's a real problem in either high-speed
or low-noise-analoge circuitry (if the device happens to use both
high-speed digianl and low-noise analogue circuitry, you've got a lot of
work to do...)
In the cae of the C64, it's very likely that loads on one of the 5V lines
could affect the other line trough the common ground.
-tony
Roy wrote:
> Because they really need to have those two +5VDC supplies separate an=
d
independent of each other.
They aren't independent. They share a common ground reference. 
1 Jul
1 Jul
1:07 a.m.
Eric Smith wrote:
I wote:
If I'm reading the C64 schematic (Sam's photofact version) correctly, the
ground-side diodes of the two bridges (the original low-current one in the
C64 and the new/main one in the power supply) would end up in parallel
(or almost in parallel: there's a noise suppression inductor, fuse, etc.
involved), so one may have unpredictable behaviour as to which diodes take
the current and/or issues with unintended current flow in some supply paths.
I haven't looked at what the low-current bridge diodes are rated for,
perhaps it would work for the currents involved, but I think it looks bad
Why does it require isolation between the 9VAC
and the +5V DC? It's not
obvious to me from the schematic.
Roy wrote:
The 9VAC supply is fed into a voltage doubler to
derive the regulated +12V
and a separate +5VDC supply, and I don't think that either of those 9VAC
lines can be grounded.
Neither side needs to be grounded.
The C64 *already* has a bridge rectifier and 5V linear regulator powered
by the 9VAC input to produce an auxiliary 5V supply, so I don't see why
building an external power supply using a transformer with a single 9VAC
secondary, and a bridge rectifier and 5V regulator (linear or switching)
would be a problem.
However, I haven't tried it, and don't accept any responsibility for
anyone else trying it.
Eric from a 'design principles' perspective.
If one were willing to modify the C64 you could open the ground lead of the
existing bridge (so that you have two half-bridges for the two positive sides,
and one half-bridge for the ground side).
Or perhaps the ground-side diodes of the bridge in the C64 would just go poof and
effectively open the ground lead for you :)
1:26 p.m.
Brent wrote:
so one may have unpredictable behaviour as to which
diodes take
the current and/or issues with unintended current flow in some supply
paths.
It generally won't matter that much which bridge is providing
the ground return path. It will provide the necessary reference
voltage.
If the lower-rated diode happens to have a slightly lower forward
drop at low current, it will start carrying more current, but that
will make its forward drop rise, and the higher-rated diode will
then start conducting more. (Unless the forward ratings of the
two bridges are significantly different.)
I haven't looked at what the low-current bridge
diodes are rated for,
perhaps it would work for the currents involved, but I think it looks bad
from a 'design principles' perspective.
I won't claim that it's great, but I've seen it done in many pieces
of equipment, and haven't ever actually seen a problem result from
it.
If one were willing to modify the C64 you could open
the ground lead of
the existing bridge (so that you have two half-bridges for the two
positive sides, and one half-bridge for the ground side).
That will cause a worse problem than the one you're trying to solve.
Eric
30 Jun
30 Jun
1:48 p.m.
Roy J. Tellason wrote:
On Sunday 29 June 2008 20:08, Ray Arachelian wrote:
There are plenty of transformers around with two 9V secondaries. I'd
reckon on using on of at least 20VA rating even if you have a switching
regulator.
I went on to the RS Components web site and found this, despite its
being an utter pig to search:
http://uk.rs-online.com/web/search/searchBrowseAction.html?method=getProduc…
(Note for our American readers. RS Components is not Tandy, it's the
supplier formerly known as Radio Spares. People still sometimes call it
Radio Spares, although AFAIK that hasn't been its name for at least a
quarter century...)
Philip.
Seth Morabito wrote:
No.
The 9VAC has to be a separate transformer winding from the one that provides
the +5VDC eventually, because of how it's used... Does anyone know of a commercially available
replacement power supply,
before I go off and build one? A linear supply would be trivial to
design, but I've never done a switching power supply, which I suppose
would be greatly preferable. The trick with the C64 is that it
requires both 9V AC and +5V DC. (I've considered frankensteining
together 9V AC and +5V DC wall-wart adapters onto the same DIN-7
cable, but it just feels so very very wrong).
Sounds like you just need a single
9VAC power supply, a bridge, a
voltage regulator, and perhaps some caps to clean up the signal a bit.
The trick is to provide enough wattage.
1 Jul
1 Jul
7:09 p.m.
There are plenty of transformers around with two 9V
secondaries. I'd
reckon on using on of at least 20VA rating even if you have a switching
regulator.
I'd proably go for overkill and get a 50VA one. But then I like
over-rating power-handling components...
I went on to the RS Components web site and found this, despite its
being an utter pig to search:
http://uk.rs-online.com/web/search/searchBrowseAction.html?method=getProduc…
(Note for our American readers. RS Components is not Tandy, it's the
supplier formerly known as Radio Spares. People still sometimes call it
I thought it was all one word -- Radiospares. I still have a few -- a
very few -- components wih that name on them.
Radio Spares, although AFAIK that hasn't been its
name for at least a
quarter century...)
I believe the name changed in 1972. The RS sales reps get annoyed if you
call them Radiospares, but everyone does :-).
-tony
11:32 p.m.
On Mon, Jun 30, 2008 at 1:48 PM, Philip Belben <philip at axeside.co.uk> wrote:
Roy J. Tellason wrote:
Oddly enough, whereas two 9V secondary windings seem common in the UK,
I'm having a VERY difficult time finding one in the US. I suppose
it's got something to do with the fact that UK/European transformers
are stepping down from 230V mains, where the North American ones are
stepping down from 110-120V mains.
I have been able to find transformers with a 115 V primary winding and
two 18 V secondary windings with center taps. I assume I can use the
center taps, but honestly I'm not sure. Time to consult some higher
authorities! (i.e., Chapter 6 of "The Art of Electronics" and Chapter
17 of "The ARRL Handbook"!)
-Seth
The 9VAC has to be a separate transformer winding
from the one that
provides the +5VDC eventually, because of how it's used...
There are plenty of transformers around with two 9V secondaries. I'd reckon
on using on of at least 20VA rating even if you have a switching regulator.
7:19 p.m.
On Mon, Jun 30, 2008 at 1:48 PM, Philip Belben <philip at axeside.co.uk> wrote:
That shouldn't make any difference (you can wind the primary winding for
any input voltage, and have any combination of secondary windings that
you like). In fact many (although not all) transofrmers sold in the UK
have a pair of 115V primary windings which you connect in series for 230V
or parallel for 115V input.
Note, of course, that when connecting windings together, the polarity
_does_ matter. It is AC, but you need to get the phase correct. Otherwise
you may end up effectively short-circuiting things and blowing fuses or
worse.
Roy J. Tellason wrote:
Oddly enough, whereas two 9V secondary windings seem common in the UK,
I'm having a VERY difficult time finding one in the US. I suppose
it's got something to do with the fact that UK/European transformers
are stepping down from 230V mains, where the North American ones are
stepping down from 110-120V mains. The 9VAC has to be a separate transformer winding
from the one that
provides the +5VDC eventually, because of how it's used...
There are plenty of transformers around with two 9V secondaries. I'd reckon
on using on of at least 20VA rating even if you have a switching regulator.
I have been able to find transformers with a 115 V primary winding and
two 18 V secondary windings with center taps. I assume I can use the
center taps, but honestly I'm not sure. Time to consult some higher
You can, but you'd then only be using half of each secondary winding
(you'd use the tap and one end, of course). You could use the whole of
one winding to provide the pwoer for your 5V regulator, by using a biphase
(2 diode) rather than a bridge rectifier.
Can you get a trapsformer with 2 9V centre-tapped windings? You could
simply ignore the taps then.
-tony
2 Jul
2 Jul
7:33 a.m.
On Wednesday 02 July 2008, Seth Morabito wrote:
Oddly enough, whereas two 9V secondary windings seem
common in the
UK, I'm having a VERY difficult time finding one in the US. I
suppose it's got something to do with the fact that UK/European
transformers are stepping down from 230V mains, where the North
American ones are stepping down from 110-120V mains.
This may work for you:
http://www.allelectronics.com/make-a-store/item/TX-1616/TRANSFORMER-16VCT/1…
Pat
--
Purdue University Research Computing --- http://www.rcac.purdue.edu/
The Computer Refuge --- http://computer-refuge.org
9:36 a.m.
On Wednesday 02 July 2008 02:32, Seth Morabito wrote:
On Mon, Jun 30, 2008 at 1:48 PM, Philip Belben
<philip at axeside.co.uk> wrote:
Which chapter depends on what edition of the handbook. :-)
If you're talking about a full-wave (4-diode) bridge across a 9V winding you
can get the same result by using two diodes with an 18V winding. For the
other, where what you want is only 9VAC, you can use half the winding,
just one end and the center tap and not use the other end.
--
Member of the toughest, meanest, deadliest, most unrelenting -- and
ablest -- form of life in this section of space, ?a critter that can
be killed but can't be tamed. ?--Robert A. Heinlein, "The Puppet Masters"
-
Information is more dangerous than cannon to a society ruled by lies. --James
M Dakin
Roy J. Tellason wrote:
Oddly enough, whereas two 9V secondary windings seem common in the UK,
I'm having a VERY difficult time finding one in the US. I suppose
it's got something to do with the fact that UK/European transformers
are stepping down from 230V mains, where the North American ones are
stepping down from 110-120V mains.
I have been able to find transformers with a 115 V primary winding and
two 18 V secondary windings with center taps. I assume I can use the
center taps, but honestly I'm not sure. Time to consult some higher
authorities! (i.e., Chapter 6 of "The Art of Electronics" and Chapter
17 of "The ARRL Handbook"!) The 9VAC has to be a separate transformer winding
from the one that
provides the +5VDC eventually, because of how it's used...
There are plenty of transformers around with two 9V secondaries. I'd
reckon on using on of at least 20VA rating even if you have a switching
regulator. 
8:50 p.m.
From: rtellason at verizon.net
On Wednesday 02 July 2008 02:32, Seth Morabito wrote:
Hi
I thought I might mention that one could get a 12v transformer and remove
some turns. The easiest ones are the double bobin types used now days
for isolation. These are usually easiest to unwind.
Dwight
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On Mon, Jun 30, 2008 at 1:48 PM, Philip Belben
wrote:
Which chapter depends on what edition of the handbook. :-)
If you're talking about a full-wave (4-diode) bridge across a 9V winding you
can get the same result by using two diodes with an 18V winding. For the
other, where what you want is only 9VAC, you can use half the winding,
just one end and the center tap and not use the other end.
Roy J. Tellason wrote:
Oddly enough, whereas two 9V secondary windings seem common in the UK,
I'm having a VERY difficult time finding one in the US. I suppose
it's got something to do with the fact that UK/European transformers
are stepping down from 230V mains, where the North American ones are
stepping down from 110-120V mains.
I have been able to find transformers with a 115 V primary winding and
two 18 V secondary windings with center taps. I assume I can use the
center taps, but honestly I'm not sure. Time to consult some higher
authorities! (i.e., Chapter 6 of "The Art of Electronics" and Chapter
17 of "The ARRL Handbook"!) The 9VAC has to be a separate transformer winding
from the one that
provides the +5VDC eventually, because of how it's used...
There are plenty of transformers around with two 9V secondaries. I'd
reckon on using on of at least 20VA rating even if you have a switching
regulator.
4 Jul
4 Jul
1:52 p.m.
Roy J. Tellason wrote:
If you're talking about a full-wave (4-diode)
bridge across a 9V winding you
can get the same result by using two diodes with an 18V winding. For the
other, where what you want is only 9VAC, you can use half the winding,
just one end and the center tap and not use the other end.
That would be ideal. Just remember that the 18V winding will be rated
for half the current that a 9V winding would have been, and that still
applies even if you only use half the winding. In this case I'd
definitely follow Tony's advice and get a transformer rated for 50VA
(18V at 2*1.4A) or more.
Philip.
6:40 p.m.
Roy J. Tellason wrote:
Now, this is more your filed than mine, but the rating of a transformer
is determined by at least 2 things :
1) 'Copper losses' due to the resisance of the secondary winding
2) Ditto for the primary winding
3) The size of the core / the flux density in the core.
Now, I think that (2) and (3) would be the same whether you used the
whole winding or half the winding at twice the current. And for small
transformers, the copper loss in the secondary is rarely the limiting
factor (For example it's very rare for the seocndary to be the winding
that fiales on a burn-out).
Soe while I'd not try and use half the secodnary at twice the rated
current, I think you would get away with rather more than the current you
could draw if you used the whole winding.
But then again I like over-rating transformers, so I'd probably not do
this anyway.
-tony
If you're talking about a full-wave (4-diode)
bridge across a 9V winding you
can get the same result by using two diodes with an 18V winding. For the
other, where what you want is only 9VAC, you can use half the winding,
just one end and the center tap and not use the other end.
That would be ideal. Just remember that the 18V winding will be rated
for half the current that a 9V winding would have been, and that still
applies even if you only use half the winding. In this case I'd
5 Jul
5 Jul
1:12 p.m.
On Friday 04 July 2008 21:40, Tony Duell wrote:
I'd tend to agree with this.
Roy J.
Tellason wrote:
Now, this is more your filed than mine, but the rating of a transformer
is determined by at least 2 things :
1) 'Copper losses' due to the resisance of the secondary winding
2) Ditto for the primary winding
3) The size of the core / the flux density in the core.
Now, I think that (2) and (3) would be the same whether you used the
whole winding or half the winding at twice the current. And for small
transformers, the copper loss in the secondary is rarely the limiting
factor (For example it's very rare for the seocndary to be the winding
that fiales on a burn-out). If you're talking about a full-wave (4-diode)
bridge across a 9V
winding you can get the same result by using two diodes with an 18V
winding. For the other, where what you want is only 9VAC, you can
use half the winding, just one end and the center tap and not use the
other end.
That would be ideal. Just remember that the 18V winding will be rated
for half the current that a 9V winding would have been, and that still
applies even if you only use half the winding. In this case I'd Soe while I'd not try and use half the secodnary
at twice the rated
current, I think you would get away with rather more than the current you
could draw if you used the whole winding.
Yup.
But then again I like over-rating transformers, so
I'd probably not do
this anyway.
If I'm going to spec one, yeah, but more often than not if I'm building
something from scratch I'll end up using some transformer I salvaged
somewhere, and mostly it works out.
--
Member of the toughest, meanest, deadliest, most unrelenting -- and
ablest -- form of life in this section of space, ?a critter that can
be killed but can't be tamed. ?--Robert A. Heinlein, "The Puppet Masters"
-
Information is more dangerous than cannon to a society ruled by lies. --James
M Dakin
29 Jun
29 Jun
6:24 p.m.
I'm sure most everyone who has ever used a C64 is aware of just how
phenomenally bad the Commodore power supply is. I have only one C64,
but both of my spare Commodore power supplies have now failed, taking
a few 4164 RAM chips with them (thankfully, I have replacements!).
Does anyone know of a commercially available replacement power supply,
before I go off and build one? A linear supply would be trivial to
design, but I've never done a switching power supply, which I suppose
would be greatly preferable. The trick with the C64 is that it
Making a switching supply to give a 50Hz or 60Hz AC output would be
decidedly non-trivial (and IMHO not senisble here). The obvious way to
get that output, given that it's unregulated, is straight from a mains
transformer secondary. A second secondary (!) on the same transformer can
be used to produce the regulated +5V line, by rectifying, smoothing, and
regulated it. That regulator could either be a linear or switching one.
I know the PSU for my C128 does exactly that (that supply is not potted,
it was possible to access the fixing screws and take the case apart). It
uses a fairly simple swithcing regulator cirucit.
Switching regulators running off the output of a mains transformer ae not
that hard to design. Firstly there's no isolation to worry about (the
transformer takes care of isolating the final 5V output from the power
line). Secondly, there are no lethal voltages around (you're staring
from, pephaps, 12V AC). And thirdly, if something does fail, the fault
current is likely to be a few amps, not a few thousand amps.
I am pretty sure any of the single-chip SMPSU controllers, an external
chopper transistor, flyback diode and inductor, and some R's and C's
could be used for this.
-tony
1 Jul
1 Jul
1:23 a.m.
On Mon, Jun 30, 2008 at 02:24:16AM +0100, Tony Duell wrote:
Making a switching supply to give a 50Hz or 60Hz AC output would be
decidedly non-trivial (and IMHO not senisble here). The obvious way to
And yet I've got a couple of C64 power supplies that are most definitely
switchers. *Someone* did it, but since they're currently 220 miles away
it's a bit hard to read the label.
We used to sell them in a computer shop I worked in about 16 years ago.
IIRC they were about 20 quid, half the price of the "real" Commodore
one.
Gordon
30 Jun
30 Jun
7:59 p.m.
On Mon, Jun 30, 2008 at 02:24:16AM +0100, Tony Duell wrote:
Just to confirm : There are mains swithces, yes? There is no
mains-frequency trandormer in them, rather the mains is recrtified,
smoothed, and then chopped/
How did they get the 9V AC output, and what freqeuncy is it? If it was at
the typial switching frequency of a small SMPUS, I would think the RFI
(from harmonics) would be horrible. And I wouldn't trust the ridge
recifier in the C64 at that frequency.
But to produce it using, say, a full H-bridge cirucit from a DC supply
seems over-complicated too.
-tony
Making a switching supply to give a 50Hz or 60Hz AC output would be
decidedly non-trivial (and IMHO not senisble here). The obvious way to
And yet I've got a couple of C64 power supplies that are most definitely
switchers. *Someone* did it, but since they're currently 220 miles away
it's a bit hard to read the label.
2 Jul
2 Jul
1:45 a.m.
On Tue, Jul 01, 2008 at 03:59:32AM +0100, Tony Duell wrote:
Just to confirm : There are mains swithces, yes? There is no
mains-frequency trandormer in them, rather the mains is recrtified,
smoothed, and then chopped/
I've never had one apart. If there's a mains transformer inside then it
must be tiny, because the power supplies are lighter than any linear
power supply I have. I suppose it's possible that the transformer is
quite small - what's the current draw on the 9V AC line anyway
Gordon
9:41 a.m.
On Wednesday 02 July 2008 04:45, gordonjcp at gjcp.net wrote:
On Tue, Jul 01, 2008 at 03:59:32AM +0100, Tony Duell
wrote:
I believe it's spec'd at 1A, if we're still talking about the original c64
supply here...
--
Member of the toughest, meanest, deadliest, most unrelenting -- and
ablest -- form of life in this section of space, ?a critter that can
be killed but can't be tamed. ?--Robert A. Heinlein, "The Puppet Masters"
-
Information is more dangerous than cannon to a society ruled by lies. --James
M Dakin
Just to confirm : There are mains swithces, yes?
There is no
mains-frequency trandormer in them, rather the mains is recrtified,
smoothed, and then chopped/
I've never had one apart. If there's a mains transformer inside then it
must be tiny, because the power supplies are lighter than any linear
power supply I have. I suppose it's possible that the transformer is
quite small - what's the current draw on the 9V AC line anyway 
1 Jul
1 Jul
6:59 a.m.
gordonjcp at gjcp.net wrote:
On Mon, Jun 30, 2008 at 02:24:16AM +0100, Tony Duell
wrote:
Were those custom jobs, or off-the-shelf supplies (that someone stuffed into a
box)? I don't think I've seen an off-the-shelf switcher with a 9VAC output*
before, but Farnell, Plessey, Astec and Weir crop up all over the place in UK
equipment...
* I don't think, anyway. Some of them do seem to have an 'aux'-type output
that the user can tweak to their own spec, though.
Making a switching supply to give a 50Hz or 60Hz
AC output would be
decidedly non-trivial (and IMHO not senisble here). The obvious way to
And yet I've got a couple of C64 power supplies that are most definitely
switchers. *Someone* did it, but since they're currently 220 miles away
it's a bit hard to read the label. 
11 a.m.
Jules Richardson wrote:
gordonjcp at gjcp.net wrote:
Late in the game, CBM switched (no pun intended) to switchers. I have a
C128 PSU that is a switcher. They were mounted in the same case, but
you can tell by the weight.
Jim
--
Jim Brain, Brain Innovations (X)
brain at jbrain.com
Dabbling in WWW, Embedded Systems, Old CBM computers, and Good Times!
Home: http://www.jbrain.com
On Mon, Jun 30, 2008 at 02:24:16AM +0100, Tony
Duell wrote:
Were those custom jobs, or off-the-shelf supplies (that someone
stuffed into a box)? I don't think I've seen an off-the-shelf switcher
with a 9VAC output* before, but Farnell, Plessey, Astec and Weir crop
up all over the place in UK equipment...
* I don't think, anyway. Some of them do seem to have an 'aux'-type
output that the user can tweak to their own spec, though.
Making a switching supply to give a 50Hz or 60Hz
AC output would be
decidedly non-trivial (and IMHO not senisble here). The obvious way to
And yet I've got a couple of C64 power supplies that are most definitely
switchers. *Someone* did it, but since they're currently 220 miles away
it's a bit hard to read the label.
30 Jun
30 Jun
8:14 p.m.
Late in the game, CBM switched (no pun intended) to
switchers. I have a
C128 PSU that is a switcher. They were mounted in the same case, but
you can tell by the weight.
I don't know how new my C128 supply is, but it uses a swithcing regulator
for the +5V output. The input to that regulator comes from a
mains-frequency transformer, another secondary winding of wich provides
the 9V AC to the machine.
So, it's a swithcing regulator, but it's not what is often meant by a
switcher where you rectifiy the mains and then re-chop it (and thus have
no mains-frequency transformer). Did Commodore ever use that sort of
supply wit the C64/C128?
-tony
1 Jul
1 Jul
2:22 p.m.
Jim Brain wrote:
These are third-party, in a case more-or-less reminiscent of the old
style C64/VIC-20 PSU, but definitely lighter.
Gordon
Jules Richardson wrote:
* I don't
think, anyway. Some of them do seem to have an 'aux'-type
output that the user can tweak to their own spec, though.
Late in the game, CBM switched (no pun intended) to switchers. I have a
C128 PSU that is a switcher. They were mounted in the same case, but
you can tell by the weight.
2:49 p.m.
Gordon JC Pearce wrote:
Jim Brain wrote:
These are third-party, in a case more-or-less reminiscent of the old
style C64/VIC-20 PSU, but definitely lighter.
Gordon
are you referring to mine? If so, I will check for sure, but I am
almost positive there are actual CBM HD power supplies.
Jim
--
Jim Brain, Brain Innovations (X)
brain at jbrain.com
Dabbling in WWW, Embedded Systems, Old CBM computers, and Good Times!
Home: http://www.jbrain.com
Jules Richardson wrote:
* I
don't think, anyway. Some of them do seem to have an 'aux'-type
output that the user can tweak to their own spec, though.
Late in the game, CBM switched (no pun intended) to switchers. I
have a C128 PSU that is a switcher. They were mounted in the same
case, but you can tell by the weight.
7:35 p.m.
On Tuesday 01 July 2008 14:00, Jim Brain wrote:
Late in the game, CBM switched (no pun intended) to
switchers. I have a
C128 PSU that is a switcher. They were mounted in the same case, but
you can tell by the weight.
I don't recall ever seeing a 128 PS that wasn't a switcher. The 128D had it
inside the case with the computer, rather than separate in a "brick", but
it wasn't that different, just a little more spread out.
--
Member of the toughest, meanest, deadliest, most unrelenting -- and
ablest -- form of life in this section of space, ?a critter that can
be killed but can't be tamed. ?--Robert A. Heinlein, "The Puppet Masters"
-
Information is more dangerous than cannon to a society ruled by lies. --James
M Dakin
2 Jul
2 Jul
12:50 a.m.
Roy J. Tellason wrote:
On Tuesday 01 July 2008 14:00, Jim Brain wrote:
OK, I stand corrected. I finally got home tonight, and was smug enough
to go out and pull the units.
First, the lightweight PSU I have with a C128 is not a C128 PSU at all,
but a A500 PSU. I am sure we tested the PSU with a C128 last week (we
were going through the units prior to the C4 CBM EXPO this past
weekend), but I'll have to check. The reason's it is so light is it
only provides DC on the outputs. 5 and +-12. It simply chops mains to
get what it needs, I would guess.
The other C128 PSUs are heavy as a common brick, and Roy looks to be
right. They have what looks like a switcher under the huge transformer.
My apologies for the incorrect information. I would assume the C64 HD
PSUs (being the same as the C128 PSU, just a different plug, use the
same switcher design. I could swear, though, that the older
non-serviceable 64 PSUs are not switchers.
I have somewhere here in the stash a schematic for a MA701 PSU, that
looks to be a HD linear for the 64. I have a couple of the units. Is
the OP looking to just buy one, or is the design the big thing?
Jim
--
Jim Brain, Brain Innovations (X)
brain at jbrain.com
Dabbling in WWW, Embedded Systems, Old CBM computers, and Good Times!
Home: http://www.jbrain.com
Late in the game, CBM switched (no pun intended)
to switchers. I have a
C128 PSU that is a switcher. They were mounted in the same case, but
you can tell by the weight.
I don't recall ever seeing a 128 PS that wasn't a switcher. The 128D had it
inside the case with the computer, rather than separate in a "brick", but
it wasn't that different, just a little more spread out.
1 Jul
1 Jul
7:23 p.m.
OK, I stand corrected. I finally got home tonight,
and was smug enough
to go out and pull the units.
First, the lightweight PSU I have with a C128 is not a C128 PSU at all,
but a A500 PSU. I am sure we tested the PSU with a C128 last week (we
were going through the units prior to the C4 CBM EXPO this past
weekend), but I'll have to check. The reason's it is so light is it
only provides DC on the outputs. 5 and +-12. It simply chops mains to
get what it needs, I would guess.
The A500 PSU is, indeed, a conventional switcher. Rectifies the mains,
chops it, feeds it into a transformer, rectifies the output, and has
control feedback fro mthe 5V output to the chopper controller for
regulation. The 12V outputs just 'tag along'.
I thought it was very foolish of Commodore to have 2 PSUs with different
outputs that used the same custom connector (a thing that looks like a
square DIN plug). IIRC plugging the Amiga PSU into a C64 does no daamge
(I can't remember if the machine basically works or not), pluggling the
C64 PSU into an Amiga can do damage (applying 9V AC to DC rails).
The other C128 PSUs are heavy as a common brick, and Roy looks to be
right. They have what looks like a switcher under the huge transformer.
That's what my C128 PSU has.
-tony
2 Jul
2 Jul
2:24 p.m.
Tony Duell wrote:
JOOI, what changed between iterations of the A500 PSU? I had one A500 with a
beige PSU that felt like it must have dark matter inside - my other one had a
white/cream PSU which felt more like it was little more than an empty shell...
Were the beige ones non-switchmode designs, with a heavy transformer, caps and
big regulators or something? Or did they just have some serious heatsinks /
screening?
I never did take a look inside, but always meant to...
OK, I stand
corrected. I finally got home tonight, and was smug enough
to go out and pull the units.
First, the lightweight PSU I have with a C128 is not a C128 PSU at all,
but a A500 PSU. I am sure we tested the PSU with a C128 last week (we
were going through the units prior to the C4 CBM EXPO this past
weekend), but I'll have to check. The reason's it is so light is it
only provides DC on the outputs. 5 and +-12. It simply chops mains to
get what it needs, I would guess.
The A500 PSU is, indeed, a conventional switcher.
9:40 a.m.
On Wednesday 02 July 2008 03:50, Jim Brain wrote:
I could swear, though, that the older non-serviceable
64 PSUs are not
switchers.
Yup. I did take a couple of those apart, though eventually I decided that it
just wasn't worth the hassle to try and get past all that potting compound,
and what's in there is a fuse (!), a 5V regulator running of a bridge, etc.
like you'd expect for a simple linear supply.
One of the funnier aspects of it is that there were some where the heatsink
for the regulator went along one short side and both long sides, and others
where the heatsink only went partway along the long sides, I guess they
figured they could cut corners there too?
When we had the shop we had such a pile of those that at one point I used to
joke about how I was gonna stick 'em all together and make a lawn sculpture
for them down there in West Chester...
--
Member of the toughest, meanest, deadliest, most unrelenting -- and
ablest -- form of life in this section of space, ?a critter that can
be killed but can't be tamed. ?--Robert A. Heinlein, "The Puppet Masters"
-
Information is more dangerous than cannon to a society ruled by lies. --James
M Dakin
1 Jul
1 Jul
10:48 a.m.
On Tue, Jul 1, 2008 at 1:23 AM, <gordonjcp at gjcp.net> wrote:
On Mon, Jun 30, 2008 at 02:24:16AM +0100, Tony Duell
wrote:
I haven't looked at the AC circuitry in the C64, is it dependent on
the input being AC? I've a fair amount of equipment that ships with
an AC wall wart that is perfectly fine with DC. If all the AC is
doing is feeding a rectifier that can handle the full current through
any path, DC would probably do the job.
If there's actual items that require AC (transformers, things that
generate clocks from the AC), then, of course, it won't work.
Making a switching supply to give a 50Hz or 60Hz AC output would be
decidedly non-trivial (and IMHO not senisble here). The obvious way to
And yet I've got a couple of C64 power supplies that are most definitely
switchers. *Someone* did it, but since they're currently 220 miles away
it's a bit hard to read the label.
We used to sell them in a computer shop I worked in about 16 years ago.
IIRC they were about 20 quid, half the price of the "real" Commodore
one.
11:48 a.m.
On Tue, Jul 1, 2008 at 10:48 AM, Eric J Korpela
<korpela at ssl.berkeley.edu> wrote:
If there's actual items that require AC
(transformers, things that
generate clocks from the AC), then, of course, it won't work.
There is at least the time of day clock. It's driven off of the 50Hz/60Hz AC.
-Seth
1:29 p.m.
Eric J Korpela wrote:
If there's actual items that require AC
(transformers, things that
generate clocks from the AC), then, of course, it won't work.
It won't work because it feeds a voltage doubler. The 9VAC is also
provided to an expansion connector, so any number of accessories might
not work either.
7:34 p.m.
On Tuesday 01 July 2008 13:48, Eric J Korpela wrote:
I haven't looked at the AC circuitry in the C64,
is it dependent on
the input being AC? I've a fair amount of equipment that ships with
an AC wall wart that is perfectly fine with DC. If all the AC is
doing is feeding a rectifier that can handle the full current through
any path, DC would probably do the job.
If there's actual items that require AC (transformers, things that
generate clocks from the AC), then, of course, it won't work.
One of the things it feeds is a voltage doubler circuit the output of which is
fed to the 7812 +12V regulator.
--
Member of the toughest, meanest, deadliest, most unrelenting -- and
ablest -- form of life in this section of space, ?a critter that can
be killed but can't be tamed. ?--Robert A. Heinlein, "The Puppet Masters"
-
Information is more dangerous than cannon to a society ruled by lies. --James
M Dakin
7:50 a.m.
I'm sure
most everyone who has ever used a C64 is aware of just how
phenomenally bad the Commodore power supply is.
s/power supply//
*runs*
kidding, obviously - couldn't resist, though :-) 
8:24 a.m.
--- On Mon, 6/30/08, Cameron Kaiser <spectre at floodgap.com> wrote:
Yeah, you'd better run. I've got my handgun now ;-)
Remember - these kinds of things are all just part of the Commodore experience. That bond
you form with a computer after fixing it and figuring out how to make it keep going. The
homemade linear power supply from junkbox parts. The homemade 7404/MAX232 combination that
gives your computer an RS-232 port. That one 1541 with all the screws missing from the
case, so that it can be opened and realigned more easily. The mental link between you and
the computer that lets you know just when your disk drive needs to be realigned (hint:
every week or so).
See - these little things that people complain about like the failing power supplies
aren't downsides at all! They're what makes us love our Commodores. They potted
those supplies together to encourage us to simply clip the leads off and build new ones.
The disk drives overheat to inspire us to cut little blocks of wood to place between two
stacked 1541's to allow the bottom one to vent. There are no "jumpers" in
those drives - you have to cut things with a knife - an important life skill. The system
unit lacks a reset switch because installing one yourself is a rite of C64 passage.
The C64 - the superb computer that's just crummy enough to keep things interesting.
-Ian
> I'm
sure most everyone who has ever used a C64
is aware of just how
phenomenally bad the Commodore power supply is.
s/power supply//
*runs*
kidding, obviously - couldn't resist, though :-)
8:24 a.m.
--- On Mon, 6/30/08, Cameron Kaiser <spectre at floodgap.com> wrote:
Yeah, you'd better run. I've got my handgun now ;-)
Remember - these kinds of things are all just part of the Commodore experience. That bond
you form with a computer after fixing it and figuring out how to make it keep going. The
homemade linear power supply from junkbox parts. The homemade 7404/MAX232 combination that
gives your computer an RS-232 port. That one 1541 with all the screws missing from the
case, so that it can be opened and realigned more easily. The mental link between you and
the computer that lets you know just when your disk drive needs to be realigned (hint:
every week or so).
See - these little things that people complain about like the failing power supplies
aren't downsides at all! They're what makes us love our Commodores. They potted
those supplies together to encourage us to simply clip the leads off and build new ones.
The disk drives overheat to inspire us to cut little blocks of wood to place between two
stacked 1541's to allow the bottom one to vent. There are no "jumpers" in
those drives - you have to cut things with a knife - an important life skill. The system
unit lacks a reset switch because installing one yourself is a rite of C64 passage.
The C64 - the superb computer that's just crummy enough to keep things interesting.
-Ian
> I'm
sure most everyone who has ever used a C64
is aware of just how
phenomenally bad the Commodore power supply is.
s/power supply//
*runs*
kidding, obviously - couldn't resist, though :-) 
10:41 a.m.
And thusly were the wise words spake by Seth Morabito
I'm sure most everyone who has ever used a C64 is aware of just how
phenomenally bad the Commodore power supply is. I have only one C64,
but both of my spare Commodore power supplies have now failed, taking
a few 4164 RAM chips with them (thankfully, I have replacements!).
Does anyone know of a commercially available replacement power supply,
before I go off and build one? A linear supply would be trivial to
design, but I've never done a switching power supply, which I suppose
would be greatly preferable. The trick with the C64 is that it
requires both 9V AC and +5V DC. (I've considered frankensteining
together 9V AC and +5V DC wall-wart adapters onto the same DIN-7
cable, but it just feels so very very wrong).
I'd love to hear from other Commie fans who've solved the power problem.
Use a C128 power supply, but replace the C128 power connector with one
from a C64 power supply, making sure to connect the
right wires to get
the right voltages on each of the C64 power pins. Then you will
have
an heavy-duty power supply that can handle a SuperCPU, RAM expansion,
etc..
Cheers,
Bryan
4:19 p.m.
Seth Morabito wrote:
The trick with the C64 is that it
requires both 9V AC and +5V DC. (I've considered frankensteining
together 9V AC and +5V DC wall-wart adapters onto the same DIN-7
cable, but it just feels so very very wrong).
Like this:
<http://c64.digitalscream.com/Slappy/slappys-power-supply.JPG>
The power supply in that photo caused quite a stir in the C= community
earlier this year. You can read more about the sordid affair here:
<http://groups.google.com/group/comp.sys.cbm/browse_thread/thread/b34f9bdb9522b96b/ad2abef064030e2a>
The consensus was that going the wall-wart route isn't wise.
--
Golan Klinger <gklinger at gmail.com>
Dark is the suede that mows like a harvest.
4:49 p.m.
On Mon, Jun 30, 2008 at 4:19 PM, Golan Klinger <gklinger at gmail.com> wrote:
Seth Morabito wrote:
Aha! Well, I'm glad that you pointed this out. It seems like the
wall-wart path is a false economy.
I'm going to build my own simple linear power supply. I'll go looking
for power transformers with two 9V secondary windings this week.
-Seth
The trick with the C64 is that it
requires both 9V AC and +5V DC. (I've considered frankensteining
together 9V AC and +5V DC wall-wart adapters onto the same DIN-7
cable, but it just feels so very very wrong).
Like this:
<http://c64.digitalscream.com/Slappy/slappys-power-supply.JPG>
The power supply in that photo caused quite a stir in the C= community
earlier this year. You can read more about the sordid affair here:
7:49 p.m.
The trick with the C64 is that it
requires both 9V AC and +5V DC. (I've considered frankensteining
together 9V AC and +5V DC wall-wart adapters onto the same DIN-7
cable, but it just feels so very very wrong).
Like this:
<http://c64.digitalscream.com/Slappy/slappys-power-supply.JPG>
The power supply in that photo caused quite a stir in the C= community
earlier this year. You can read more about the sordid affair here: 
2 Jul
2 Jul
2:34 p.m.
Tony Duell wrote:
Personally I regard them as about the most dangerous
thing around. I've
yet to see one with proper mains fusing, most don't have output
current limiting, and so on.One common type sold in the UK has a 4-way
cross-shapped plug on it (3.5mm jack, 2.5mm jack, 2.1mm coax, 2.5mm coax)
with separate 1.3mm coax ('Walkman' plug) and a 9V battery clip on the
same cable. It's very easy to get a short-circuited output if those
conenctors touch each other.
It's even more "fun" when the 4-way is plugged into the power jack on a
machine, and the 9V connector wipes against, say, an edge connector. Instant
fried chips, and not the edible kind.
That's pretty much how my Jupiter Ace got wrecked (and speaking of which, I
*still* haven't managed to get in touch with the guy who was *supposed* to be
repairing it....)
--
Phil.
classiccmp at philpem.me.uk
http://www.philpem.me.uk/
7:29 p.m.
On Wednesday 02 July 2008 17:34, Philip Pemberton wrote:
Tony Duell wrote:
Then there was the customer who plugged his power supply in to the _back_ of
his 64, in the only socket where it would fit -- the video connector.
Funny how that works sometimes...
--
Member of the toughest, meanest, deadliest, most unrelenting -- and
ablest -- form of life in this section of space, ?a critter that can
be killed but can't be tamed. ?--Robert A. Heinlein, "The Puppet Masters"
-
Information is more dangerous than cannon to a society ruled by lies. --James
M Dakin
Personally I regard them as about the most
dangerous thing around. I've
yet to see one with proper mains fusing, most don't have output
current limiting, and so on.One common type sold in the UK has a 4-way
cross-shapped plug on it (3.5mm jack, 2.5mm jack, 2.1mm coax, 2.5mm coax)
with separate 1.3mm coax ('Walkman' plug) and a 9V battery clip on the
same cable. It's very easy to get a short-circuited output if those
conenctors touch each other.
It's even more "fun" when the 4-way is plugged into the power jack on a
machine, and the 9V connector wipes against, say, an edge connector.
Instant fried chips, and not the edible kind.
That's pretty much how my Jupiter Ace got wrecked (and speaking of which, I
*still* haven't managed to get in touch with the guy who was *supposed* to
be repairing it....)
3 Jul
3 Jul
7:17 a.m.
And thusly were the wise words spake by Roy J. Tellason
On Wednesday 02 July 2008 17:34, Philip Pemberton wrote:
^^^^^
Did something light up inside of the poor 64?
Cheers,
Bryan
Tony Duell wrote:
Then there was the customer who plugged his power supply in to the _back_ of
his 64, in the only socket where it would fit -- the video connector.
Funny how that works sometimes... Personally I regard them as about the most
dangerous thing around. I've
yet to see one with proper mains fusing, most don't have output
current limiting, and so on.One common type sold in the UK has a 4-way
cross-shapped plug on it (3.5mm jack, 2.5mm jack, 2.1mm coax, 2.5mm coax)
with separate 1.3mm coax ('Walkman' plug) and a 9V battery clip on the
same cable. It's very easy to get a short-circuited output if those
conenctors touch each other.
It's even more "fun" when the 4-way is plugged into the power jack on a
machine, and the 9V connector wipes against, say, an edge connector.
Instant fried chips, and not the edible kind.
That's pretty much how my Jupiter Ace got wrecked (and speaking of which, I
*still* haven't managed to get in touch with the guy who was *supposed* to
be repairing it....)
3:57 p.m.
On Thursday 03 July 2008 10:17, Bryan Pope wrote:
And thusly were the wise words spake by Roy J.
Tellason
Not much, and that power supply had really poor resolution, too!
--
Member of the toughest, meanest, deadliest, most unrelenting -- and
ablest -- form of life in this section of space, ?a critter that can
be killed but can't be tamed. ?--Robert A. Heinlein, "The Puppet Masters"
-
Information is more dangerous than cannon to a society ruled by lies. --James
M Dakin
On Wednesday 02 July 2008 17:34, Philip Pemberton
wrote:
^^^^^
Did something light up inside of the poor 64? Tony Duell wrote:
Then there was the customer who plugged his power supply in to the _back_
of his 64, in the only socket where it would fit -- the video connector.
Funny how that works sometimes... Personally I regard them as about the most
dangerous thing around.
I've yet to see one with proper mains fusing, most don't have output
current limiting, and so on.One common type sold in the UK has a
4-way cross-shapped plug on it (3.5mm jack, 2.5mm jack, 2.1mm coax,
2.5mm coax) with separate 1.3mm coax ('Walkman' plug) and a 9V
battery clip on the same cable. It's very easy to get a
short-circuited output if those conenctors touch each other.
It's even more "fun" when the 4-way is plugged into the power jack on a
machine, and the 9V connector wipes against, say, an edge connector.
Instant fried chips, and not the edible kind.
That's pretty much how my Jupiter Ace got wrecked (and speaking of
which, I *still* haven't managed to get in touch with the guy who was
*supposed* to be repairing it....)
30 Jun
30 Jun
5:56 p.m.
On Monday 30 June 2008 19:19, Golan Klinger wrote:
Seth Morabito wrote:
Oh my.
The trick with the C64 is that it
requires both 9V AC and +5V DC. (I've considered frankensteining
together 9V AC and +5V DC wall-wart adapters onto the same DIN-7
cable, but it just feels so very very wrong).
Like this:
<http://c64.digitalscream.com/Slappy/slappys-power-supply.JPG> The power supply in that photo caused quite a stir in
the C= community
earlier this year. You can read more about the sordid affair here:
<http://groups.google.com/group/comp.sys.cbm/browse_thread/thread/b34f9bdb9
522b96b/ad2abef064030e2a>
The consensus was that going the wall-wart route isn't wise.
Apparently that "custom designed power supply" lasted something like a whole
three hours? That may have some bearing on it. I've seen very few wall
warts that are rated high enough in terms of output current, for the most
part.
--
Member of the toughest, meanest, deadliest, most unrelenting -- and
ablest -- form of life in this section of space, ?a critter that can
be killed but can't be tamed. ?--Robert A. Heinlein, "The Puppet Masters"
-
Information is more dangerous than cannon to a society ruled by lies. --James
M Dakin
7:43 p.m.
Golan Klinger wrote:
Seth Morabito wrote:
As one of the electrical engineers that commented on the issues with
that "supply", I want to point out that the idea isn't so horrid. Wall
warts, if you can find suitably rated ones, can rise to the challenge.
My main issue was that:
I didn;t think the warts were suitably powered for the load. It's
impossible to tell from the pics, but the failure of the unit seems to
vindicate me.
I mentioned wall-warts were only UL rated if they are used outside an
enclosure. Putting them in a box made me cringe.
Selling a unit built in this way without disclosing the implementation
was inexcusable, in my opinion.
But, if you're trying to preserve your machine, this would probably not
be my first choice. I just wanted to point out that you might see me
use wallwarts at some point in this fashion, but I doubt I'd sell such a
unit, and I know I'd not mount in a box.
Jim
--
Jim Brain, Brain Innovations (X)
brain at jbrain.com
Dabbling in WWW, Embedded Systems, Old CBM computers, and Good Times!
Home: http://www.jbrain.com
The trick with the C64 is that it
requires both 9V AC and +5V DC. (I've considered frankensteining
together 9V AC and +5V DC wall-wart adapters onto the same DIN-7
cable, but it just feels so very very wrong).
Like this:
<http://c64.digitalscream.com/Slappy/slappys-power-supply.JPG>
The power supply in that photo caused quite a stir in the C= community
earlier this year. You can read more about the sordid affair here:
<http://groups.google.com/group/comp.sys.cbm/browse_thread/thread/b34f9bdb9522b96b/ad2abef064030e2a>
The consensus was that going the wall-wart route isn't wise.
6:29 p.m.
this might work for u its not mu ebay auction i know nothing about it
http://tiny.cc/cEVkC
On 6/29/08, Seth Morabito <sethm at loomcom.com> wrote:
I'm sure most everyone who has ever used a C64 is aware of just how
phenomenally bad the Commodore power supply is. I have only one C64,
but both of my spare Commodore power supplies have now failed, taking
a few 4164 RAM chips with them (thankfully, I have replacements!).
Does anyone know of a commercially available replacement power supply,
before I go off and build one? A linear supply would be trivial to
design, but I've never done a switching power supply, which I suppose
would be greatly preferable. The trick with the C64 is that it
requires both 9V AC and +5V DC. (I've considered frankensteining
together 9V AC and +5V DC wall-wart adapters onto the same DIN-7
cable, but it just feels so very very wrong).
I'd love to hear from other Commie fans who've solved the power problem.
-Seth
6:59 p.m.
On Monday 30 June 2008 21:29, Chris Halarewich wrote:
this might work for u its not mu ebay auction i know
nothing about it
http://tiny.cc/cEVkC
Dunno why that took me to ebay.ca (which I never even knew existed before).
That appears to be another aftermarket supply, and I *may* have seen those
before. No power on-off switch or user-accessible fuse is apparent -- I'm
going to ask the seller about it by way of ebay.com, the item number if
anyone's interested is 250263634041.
Way cheaper than the CPS-10, but then not as robust or as well-built, I'd
say.
--
Member of the toughest, meanest, deadliest, most unrelenting -- and
ablest -- form of life in this section of space, ?a critter that can
be killed but can't be tamed. ?--Robert A. Heinlein, "The Puppet Masters"
-
Information is more dangerous than cannon to a society ruled by lies. --James
M Dakin
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