In the latest IEEE Spectrum magazine there is an article on page 24,
'Hands On - Why stop at breadboarding when custom PCBs are easy to
design and cheap to get made?', by James Turner.
Summary of this: He used Eagle to design/layout the board (which
seemed to be free), you have to do the trace routing manually, and
your pcb is 'batched' with others to keep the price way down.
At 02:52 PM 4/23/2010, you wrote:
>On 4/22/10, Andrew Lynch <lynchaj at yahoo.com> wrote:
> > Hi! It pains me to ask this, what vendors are hobbyists using
> for low cost,
> > low quantity prototype PCBs?
>
>I had a run recently done by Gold Phoenix
>(http://www.goldphoenixpcb.biz/) - 2 layer board, approx 3"x3.5", 100%
>through-hole design, no fancy features (it was an 80C52 design that is
>now sporting an ATmega8515). I sent them Gerber files from EagleCAD
>and they panellized for free - their work size is 155 sq in, so I got
>16 boards for $99. For the application at hand, it was a good deal
>and I was happy with the results.
>
>Gold Phoenix was recommended to me by the Makerbot guys. I've done
>one run and was entirely satisfied. We will probably do a "Rev 2"
>through them as well.
>
>-ethan
Has anyone on the list seen or work with one of these? I received a
Morrow M-20 8-inch hard disk along with my N* Horizon and found the
Memorex 102 disk mechanism inside (what a beast!).
At initial power-up, a 10-ohm 5W resistor near the power connector let out
a puff of smoke (the drive was in the process of spinning up). I killed
power and started checking components carefully. There were no ominous
readings across the 5V logic power rails and I traced things out enough to
determine that this resistor was between the +24V power input and whatever
lies downstream (probably motor servo).
The platters move freely, so the motor certainly wasn't bound up. When I
checked power supply voltages (it's an analog supply), I discovered that
the +24V rail was delivering +44V (!) and the -12V rail was -15V. The 5V
rail was right on spec.
For a quick reality check, I plugged the supply into my bench variac and
adjusted input voltage to yield +24V at the motor supply. Both other
rails were within spec at this point.
When I tried again to spin the drive up at the correct voltage, the series
resistor became extremely hot although, again, the drive was on its way to
full rotational speed at the time. I measured 20V across the 10-ohm
resistor, which calculates to 2A and a dissipation of 10W. The latter
number explains the heat. Not wanting to tempt fate, I shut things down
quickly.
So, opinions and suggestions please? A two-amp draw does not seem
excessive to me, although clearly it's outside the design parameters given
the rating of the dropping resistor. The power supply is certainly
reparable, and before anyone asks it is delivering clean DC - ripple is on
the order of 10mv. Why it's doubling its output is yet to be determined,
but I did find a diagram at bitsavers.
One thought that occured to me is that the +24V rail is probably powering
the voice-coil positioner in addition to the motor. I felt around
extensively, and none of the power devices involved with head motion or
servo is excessively warm. None of them appear shorted or open.
Not sure where to go from here.
Steve
--
Al wrote:
>Tim wrote:
>>> 10MB for only US$3398 (plus shipping?):
>>> http://gizmodo.com/5524908/the-hard-disk-youve-been-waiting-for
>
>> Who is the actual maker of the XCOMP physical drive in the picture? I'm not familiar with the unit.
>
>> Corvus sold the IMI (International Memories Incorporated) drive in ?1980? and there was the Seagate ST-506 in 1980 and the Shugart SA1000 in I think 1979. So I'm thinking the XCOMP ad must be the same era.
>
>> Tim.
> The earliest copy of the ad appears in the Jul 81 issue of Byte.
> Manufacturers of 10meg drives in 1981 included Miniscribe, RMS, Rodime, Tandon, and TI but
> most used similar bezels to the Seagate drives.
> The drive is interesting because it integrated the stepper inside with the actuator.
I didn't know that TI made small hard drives of that era, interesting.
Thinking of old hard drive manufacturers...
Was CMI actually making drives back in 1981? They were in Southern California like XCOMP.
By the time I saw CMI drives (1983? 1984? PC-AT days) they were being made in the far
East in large numbers, and the stepper was on the outside of the housing, but maybe
CMI made some drives domestically before that.
Tim.
I asked the creator of the mini-Altair 8800 PC about the possibility of a kit and he emailed to ask how much people would be willing to pay for one. There's no commitment, he just wants to know if it would be worth it for him to offer a kit (you would supply the modern motherboard, CPU, RAM, etc.). Interested and, if so, how much would you pay?
Mini Altair 8800 PC
http://galacticstudios.org/component/content/article/2-electronics/14-minia…
> > As he didn't mutilate an actual Altair, I will say
> > that is pretty cool
>
> I agree.
> I like the fact that he has this interfaced to Rich Cini's
> Altair32 emulator so you can operate it directly via the front panel
> switches instead of a mouse.
I was hoping he could create and sell a case/interface kit without the modern motherboard, but since the case was part of an old function generator(?) he purchased on eBay, a similar case would have to be mass produced which I suspect would be prohibitively expensive in small quantities even if produced in China. If a case kit like this was in fact made available at something approaching a reasonable price, I'd buy one in a _heartbeat_. Typical "case mods" hold no attraction for me whatsoever. One like this definitely would.
A while ago I posted about an RD53 I have which had the problem with the
sticking heads. I have now got to the point where the heads no longer stick
on the bumper, but the disk still does not work correctly. I opened it up
and watched what it did with the cover off. Once it gains speed it moves the
heads out all the way and then they just stay there with the disk spinning.
There is a whine coming from the drive, not sure of the source of this
though. Is this the right head behaviour? Below is what I got when it was
installed in a MicroVAX 2000:
>>> test 50
KA410-A V1.2
ID 08-00-2B-07-98-90
? CLK 0000.0005
NVR 0000.0001
? DZ 0000.4001
00004001 00000001 00000001 00000001 00000000 00000000
MEM 0006.0001
00600000
MM 0000.0001
FP 0000.0001
IT 0000.0001
? HDC 7730.7731
00022000 00000000 00000000
? TPC 0000.4001
FFFFFF03 FFFFFF05 FFFFFF05 FFFFFF05 FFFFFF05 FFFFFF05
FFFFFF05 FFFFFF05
SYS 0000.0001
?? NI 0000.7004 V1.3
>>>
I tried using the verifier thus:
>>> test 71
KA410-A RDver
VSmsv_QUE_unitno (0-1) ? 0
VSmsv_STS_Siz . RD53
VSmsv_QUE_RUsure (DUA0 1/0) ? 1
VSmsv_STS_RDing .
But the verifier just stuck on there and did not show any progress for a
good 20 minutes or so, I believe an RD53 should verify in about 8 minutes.
Any suggestions?
Thanks
Rob
> 10MB for only US$3398 (plus shipping?):
> http://gizmodo.com/5524908/the-hard-disk-youve-been-waiting-for
Who is the actual maker of the XCOMP physical drive in the picture? I'm not familiar with the unit.
Corvus sold the IMI (International Memories Incorporated) drive in ?1980? and there was the Seagate ST-506 in 1980 and the Shugart SA1000 in I think 1979. So I'm thinking the XCOMP ad must be the same era.
Tim.
Hi Cameron,
> I'd sort of independently determined this, although I settled on mfrtcu
> which is spr4-5, IIRC. I'm not sure if it's high enough resolution for this
> task, but as you point out, rdtsc() in the PPC nanojit is a function, so
> it may not be a significant problem. mfrtcu/mfrtcl *should* work on the 603
> and up, right?
I'm not so sure. I had a look at the rtc. Although I think there's
user-level access for both the 603 and 601 etc, the problem I see with
using it is that rtcl counts MOD 10^9 and I'd guess that the use of rdtsc
assumes MOD 2^64.
-cheers from julz @P
