15 Dec
2011
15 Dec
'11
3:37 p.m.
Tony writes:
> On 12/14/2011 08:14 PM, Mouse wrote:
> > On the other, I'm considering an AGC circuit that doesn't use a bulb,
> > but instead uses a FET as a variable resistor, and trying to figure out
> > where it's got anything nonlinear in it (assuming the amplifier is
> > running class A).
>
> Jim Williams (RIP) did a LOT of research on this. The bulb
> outperformed the FET by a gigantic margin. (just sayin'..)
I thoguht in the end he amanged ot get the FET cirucit
to be better than
the light bulb, but it took a lot of work (and probably wasn't worth it).
Good reference: AN-43: http://cds.linear.com/docs/Application%20Note/an43f.pdf
I'm sure Jim Williams thought it was worth it and I really enjoyed reading about it so
it was worth it to me for sure :-)
A highlight was Note 5: "What else should be expected when trying to replace a single
light bulb with a bunch of electronic components? I can hear Figure 39?s #327 lamp
laughing."
I had previously met Sir Denys Wilkinson and he had mentioned something to me about his
pioneering days in nuclear instrumentation (including pinball machine multichannel
analyzers). When he had told me that he had invented the D/A converter I didn't really
believe him but kinda nodded along. Then I read it in Jim Williams' application note -
with an actual reference - I felt a little sheepish in retrospect!
Tim.
16 Dec
16 Dec
3:39 a.m.
Shoppa, Tim wrote:
Tony writes:
Sorry that I'm asking, but what the heck has this todo with my question
above?
Regards,
Holm
--
Technik Service u. Handel Tiffe, www.tsht.de, Holm Tiffe,
Freiberger Stra?e 42, 09600 Obersch?na, USt-Id: DE253710583
www.tsht.de, info at tsht.de, Fax +49 3731 74200, Mobil: 0172 8790 741
> On 12/14/2011 08:14 PM, Mouse wrote:
> > On the other, I'm considering an AGC circuit that doesn't use a bulb,
> > but instead uses a FET as a variable resistor, and trying to figure out
> > where it's got anything nonlinear in it (assuming the amplifier is
> > running class A).
>
> Jim Williams (RIP) did a LOT of research on this. The bulb
> outperformed the FET by a gigantic margin. (just sayin'..)
I thoguht in the end he amanged ot get the FET
cirucit to be better than
the light bulb, but it took a lot of work (and probably wasn't worth it).
Good reference: AN-43: http://cds.linear.com/docs/Application%20Note/an43f.pdf
I'm sure Jim Williams thought it was worth it and I really enjoyed reading about it
so it was worth it to me for sure :-)
A highlight was Note 5: "What else should be expected when trying to replace a
single light bulb with a bunch of electronic components? I can hear Figure 39?s #327 lamp
laughing."
I had previously met Sir Denys Wilkinson and he had mentioned something to me about his
pioneering days in nuclear instrumentation (including pinball machine multichannel
analyzers). When he had told me that he had invented the D/A converter I didn't really
believe him but kinda nodded along. Then I read it in Jim Williams' application note -
with an actual reference - I felt a little sheepish in retrospect!
Tim. 
2:17 p.m.
I had previously met Sir Denys Wilkinson and he had
mentioned something t=
o me about his pioneering days in nuclear instrumentation (including pinb=
all machine multichannel analyzers). When he had told me that he had inve=
nted the D/A converter I didn't really believe him but kinda nodded along=
Depends on what you mean by D-A i guess...
In one of my old books on electric lighting they suggest lighting a large
room by 15 light bulbs in a 3*5 array o nthe ceiling and controllign them
by 4 switches, thus giving 15 levels of illumination (I guess 'all off'
is not illumination :-)). THye even give the best way to arrange the
light bubls controleld by each switch, so as to get fairly evnn
illumination in all cases. I consdier that ot be a D-A.
-tony
3:21 p.m.
New subject: D/As, Re: russian PDP-11 like K1801BM2 CPU Startup reading w/o address?
On 12/16/2011 05:17 PM, Tony Duell wrote:
With the combination of the room and your eyeballs acting as a
(spatial) low-pass filter? ;)
-Dave
--
Dave McGuire
New Kensington, PA
I had
previously met Sir Denys Wilkinson and he had mentioned something t=
o me about his pioneering days in nuclear instrumentation (including pinb=
all machine multichannel analyzers). When he had told me that he had inve=
nted the D/A converter I didn't really believe him but kinda nodded along=
Depends on what you mean by D-A i guess...
In one of my old books on electric lighting they suggest lighting a large
room by 15 light bulbs in a 3*5 array o nthe ceiling and controllign them
by 4 switches, thus giving 15 levels of illumination (I guess 'all off'
is not illumination :-)). THye even give the best way to arrange the
light bubls controleld by each switch, so as to get fairly evnn
illumination in all cases. I consdier that ot be a D-A.
17 Dec
17 Dec
11:58 a.m.
New subject: D/As,
In one of my
old books on electric lighting they suggest lighting a large
room by 15 light bulbs in a 3*5 array o nthe ceiling and controllign them
by 4 switches, thus giving 15 levels of illumination (I guess 'all off'
is not illumination :-)). THye even give the best way to arrange the
light bubls controleld by each switch, so as to get fairly evnn
illumination in all cases. I consdier that ot be a D-A.
With the combination of the room and your eyeballs acting as a
(spatial) low-pass filter? ;) 
16 Dec
16 Dec
9:08 p.m.
On 12/16/2011 4:17 PM, Tony Duell wrote:
That's very cool! I can't help imagining the switches sitting side by
side on the wall with 8, 4, 2, and 1 labels above them. (Set the
lighting to level 11, please. That's rather bright, could we try level
9? Thanks very much... that's perfect.) Of course 2^3, 2^2, 2^1, and
2^0 labeling would be more devious and a lot more fun. ;-)
--
Later,
Charlie C.
In God We Trust!!!
Freedom is in dire danger any time the US congress is in session...
Want to fix the post office? How about a "do not mail" list!
I had
previously met Sir Denys Wilkinson and he had mentioned something t=
o me about his pioneering days in nuclear instrumentation (including pinb=
all machine multichannel analyzers). When he had told me that he had inve=
nted the D/A converter I didn't really believe him but kinda nodded along=
Depends on what you mean by D-A i guess...
In one of my old books on electric lighting they suggest lighting a large
room by 15 light bulbs in a 3*5 array o nthe ceiling and controllign them
by 4 switches, thus giving 15 levels of illumination (I guess 'all off'
is not illumination :-)). THye even give the best way to arrange the
light bubls controleld by each switch, so as to get fairly evnn
illumination in all cases. I consdier that ot be a D-A.
-tony
17 Dec
17 Dec
12:30 p.m.
That's very cool! I can't help imagining the
switches sitting side by
side on the wall with 8, 4, 2, and 1 labels above them. (Set the
lighting to level 11, please. That's rather bright, could we try level
For some reason the book suggests usinf a pair of double switches and
numbering them in the order 2 4 1 8. I cna't think of any good reason for
this...
-tony
12:34 p.m.
New subject: Oscillators, was Re: russian PDP-11 like K1801BM2 CPU Startup reading w/o address?
On 12/15/2011 06:37 PM, Shoppa, Tim wrote:
Good heavens, I'd forgotten all about that appnote, and there it was
sitting in my archives. I really need to get cracking on this document
management and indexing system. The biological one I've been using
isn't working very well.
>> On the
other, I'm considering an AGC circuit that doesn't use a
>> bulb, but instead uses a FET as a variable resistor, and trying
>> to figure out where it's got anything nonlinear in it (assuming
>> the amplifier is running class A).
>
> Jim Williams (RIP) did a LOT of research on this. The bulb
> outperformed the FET by a gigantic margin. (just sayin'..)
I thoguht in the end he amanged ot get the FET
cirucit to be better
than the light bulb, but it took a lot of work (and probably wasn't
worth it).
Good reference: AN-43:
http://cds.linear.com/docs/Application%20Note/an43f.pdf I'm sure Jim Williams thought it was worth it and
I really enjoyed
reading about it so it was worth it to me for sure :-)
Oh yes. :-)
A highlight was Note 5: "What else should be
expected when trying to
replace a single light bulb with a bunch of electronic components? I
can hear Figure 39?s #327 lamp laughing."
:-)
I had previously met Sir Denys Wilkinson and he had
mentioned
something to me about his pioneering days in nuclear instrumentation
(including pinball machine multichannel analyzers). When he had told
me that he had invented the D/A converter I didn't really believe him
but kinda nodded along. Then I read it in Jim Williams' application
note - with an actual reference - I felt a little sheepish in
retrospect!
Oops!!
-Dave
--
Dave McGuire
New Kensington, PA
4760
days inactive
4762
days old
7 comments
5 participants
participants (5)
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ard＠p850ug1.demon.co.uk -
csquared3＠tx.rr.com -
holm＠freibergnet.de -
mcguire＠neurotica.com -
tshoppa＠wmata.com