On Aug 21, 2006, at 8:41 PM, John Griessen wrote:
Do you hack code on the old machines and also hack on their circuit
boards/ Just how much hacking are we talking about here?
Both. Lots of both! 8-) I'm currently restoring a PDP-8/e with two
RK05 disk drives, a TU56 tape subsystem, and 2
Dave,
Do you hack code on the old machines and also hack on their circuit boards/
Just how much hacking are we talking about here?
JOhn G
Dave McGuire wrote:
(I have
~200 qbus, unibus, and omnibus boards here; I hack on 'em all the time)
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Does the 60% derating term mean use 40% of the full value? Does the de in
derating imply a subtract?
John G
John Doty wrote:
I just located my copy of NASA practice no PD-ED-1201, which covers
electronic part derating. Table I in that doc calls out derating caps
by 60%. It d
You're hurtin' me here. HURTIN' ME! ;)
-Dave
On Aug 21, 2006, at 7:01 PM, Steve Meier wrote:
Stuart,
Yep it is time to put a cap on it.
Steve M.
I feel like I'm beating this horse far beyond the point where it's
already dead. . . . . .
Stuart
Stuart,
Yep it is time to put a cap on it.
Steve M.
> I feel like I'm beating this horse far beyond the point where it's
> already dead. . . . . .
> Stuart
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> I feel like I'm beating this horse far beyond the point where it's
> already dead. . . . . .
But I'm still learning stuff, so I'm OK with it.
> But I looked at your most recent layout, and another question
> occurred to me: Is there a reason you are using long, spindly traces
> [1] for VCC/GND
On Aug 21, 2006, at 12:19 PM, Stuart Brorson wrote:
I believe that back in the 70s DEC used to use two layer boards with
PWR and GND run on busses layed out on a rectilinear grid. Signal
traces were on top (IIRC) and PWR/GND on teh bottom. The DIPs
were layed out in rectangular rows following t
I updated the board online, adding five 10uF 0805s around the board.
One near each incoming power, two in the middle, and one at the other
end of the board. Plus the one 10uF on the 3.3v regulator.
I feel like I'm beating this horse far beyond the point where it's
already dead. . . . . .
But I
One more factoid for the general edification of the group: If you
google around you can also find JPL's latest derating guidelines. It
is a very good doc which I just uncovered since this discussion put me
in the mood to uncover more source material.
The doc you want is JPL-D-8545, Rev. D. Goo
On Aug 21, 2006, at 1:26 PM, Stuart Brorson wrote:
Also remember that NASA recommendations tend to be super
conservative.
I would normally agree, except that NASA's 60% rating suggests using a
10V cap to hold off 6V, which seems too low to me. A 2X derating
would suggest at least 12V to s
Also remember that NASA recommendations tend to be super conservative.
I would normally agree, except that NASA's 60% rating suggests using a
10V cap to hold off 6V, which seems too low to me. A 2X derating
would suggest at least 12V to stand off 6V, whereas my 3X derating
guideline says at l
Here are some links I found from "electrolytic capacitor lifetime":
http://www.aavidthermalloy.com/technical/papers/capacitor.shtml
http://www.nichicon-us.com/english/seihin/pdfs/e-nx.pdf
http://powerelectronics.com/mag/power_optimize_electrolytic_capacitor/index.html
http://www.evoxrifa.com/el
On Aug 21, 2006, at 5:10 AM, Stuart Brorson wrote:
For your furnace controller, you probably won't see any difference
between 1.0uF and 0.1 uF; either one will work for you. It's not
necessarily in the same class as the GHz server motherboards or 10
GHz router boards that the SI gurus argue a
> You may want to try the capacitor manufacturer websites --- Kemet,
> AVX, Nichicon, etc.
Ah, so Google isn't always my friend? ;-)
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On 8/21/06, DJ Delorie <[EMAIL PROTECTED]> wrote:
> Also, a Google search will turn up lots of info about how to
> properly select an electrolytic cap.
Too much info. What keywords should I be using?
You may want to try the capacitor manufacturer websites --- Kemet,
AVX, Nichicon, etc.
(* j
> Also, a Google search will turn up lots of info about how to
> properly select an electrolytic cap.
Too much info. What keywords should I be using?
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On Aug 21, 2006, at 12:52 PM, Stuart Brorson wrote:
I just located my copy of NASA practice no PD-ED-1201, which covers
electronic part derating. Table I in that doc calls out derating caps
by 60%. It does not distinguish between electrolytics, ceramics, or
other types of cap. You may be ab
On Aug 20, 2006, at 10:56 PM, DJ Delorie wrote:
0.1 uF or 1 uF ? Same footprint (0603), the 1uFs are a few cents more
each (er, ~ 40% more cost for 10x the capacitance).
Don't know if the 0.1uFs have some benefits inductance-wise or
ESR-wise, in general.
If they are both 0603, inductance s
> Also, with electrolytics, you need to pay attention to the temp
> rating. 85C rated caps are for cheap consumer junk. You want at
> least 105C for industrial equpt, IMO, and 125C is better
It's going to be bolted to my FURNACE. So yeah, high temp range is
good. It's on the duct that carries
What about Al electrolytics? Like, for power supply bulk filtering?
The furnace controller will be seeing 34 Vdc peak, does that mean 100v
caps?
Yes, that's what I'd do.
I just located my copy of NASA practice no PD-ED-1201, which covers
electronic part derating. Table I in that doc calls ou
What about Al electrolytics? Like, for power supply bulk filtering?
The furnace controller will be seeing 34 Vdc peak, does that mean 100v
caps?
Yes, that's what I'd do.
Also, with electrolytics, you need to pay attention to the temp
rating. 85C rated caps are for cheap consumer junk. You wa
> 1. Make sure DigiKey has stock (info available from their web site).
I have a search box on my home page that automatically selects "in
stock only". It's something I'm slightly paranoid about. I can also
alter the design after I order based on what I *actually* get.
> 2. The rule of thumb
> Yeah, my sort algorithm (stolen from the web somewhere) sorts by
> ASCII character, not by anything more intelligent. I can fix that
> at some point.
pcb has a sort-helper that does the right thing, if you want to grab a
copy of it.
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Hmmm, do you actually have 10uF 0603 ceramic caps in hand? I'd bet
dollars to doughnuts that you either haven't looked for them, or your
haven't ordered them yet (so you haven't found out that they are only
brochureware).
Digikey ECJ-1VB0J106M
It's the biggest value 0603 cap Panasonic makes (6
> > I put a copy here: http://www.delorie.com/pcb/m3a-exp-board.pcb
>
> I looked at your board. The 0603 position on the back of the board
> looks good. One thing: Why not put a couple of 10uF tantalum caps at
> strategic positions along the PWR/GND busses?
I updated the board online, adding
> Have you ever looked at the capacitance-vs-voltage curves for Y5V
> dielectric? Yuck.
I've been avoiding the 20/80 caps for anything other than bulk
bypassing, but I'm easily talked out of them completely.
OTOH this board will only see room temperature. I'll look for
high-temp-range parts fo
DJ -
On Mon, Aug 21, 2006 at 02:01:51PM -0400, DJ Delorie wrote:
> > Plus scattering some 10uF (also 0603 ceramic) around.
> Or this one: digikey PCC2233CT-ND
> 10uF 0805 ceramic, 10v, +20% -80%, only $0.20 each.
Have you ever looked at the capacitance-vs-voltage
curves for Y5V dielectric? Yuck
> Plus scattering some 10uF (also 0603 ceramic) around.
Or this one: digikey PCC2233CT-ND
10uF 0805 ceramic, 10v, +20% -80%, only $0.20 each.
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> Hmmm, do you actually have 10uF 0603 ceramic caps in hand? I'd bet
> dollars to doughnuts that you either haven't looked for them, or your
> haven't ordered them yet (so you haven't found out that they are only
> brochureware).
Digikey ECJ-1VB0J106M
It's the biggest value 0603 cap Panasonic m
Great minds think alike; I'm currently doing that. Caps are cheap, so
for the srams example, I'm using 0.1uF at each power pin (16 total),
and 1uF at the end of each sram bus (eight total). Plus scattering
some 10uF (also 0603 ceramic) around.
Hmmm, do you actually have 10uF 0603 ceramic caps
On 8/21/06, DJ Delorie <[EMAIL PROTECTED]> wrote:
Plus scattering some 10uF (also 0603 ceramic) around.
> Don't forget to derate the Ta voltage by a factor of 3. That is, if
> your VCC is 5V, you need at least a 16V Ta cap for safety.
I think they're all 16v anyway, but I'll double check.
Yo
> I looked at your board. The 0603 position on the back of the board
> looks good. One thing: Why not put a couple of 10uF tantalum caps
> at strategic positions along the PWR/GND busses?
Great minds think alike; I'm currently doing that. Caps are cheap, so
for the srams example, I'm using 0.1
I put a copy here: http://www.delorie.com/pcb/m3a-exp-board.pcb
I looked at your board. The 0603 position on teh back of the board
looks good. One thing: Why not put a couple of 10uF tantalum caps at
strategic positions along the PWR/GND busses? Perhaps one at each
power connector, and one i
> Panelize ;-)
1. It's the sq in cost that's still high.
2. I'm already putting 100 challenge boards and one sram board onto
the panel.
3. It's not like I've got *that* many four layer projects to do!
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On 8/21/06, DJ Delorie <[EMAIL PROTECTED]> wrote:
> Yuck! No GND plane! How barbaric! How '70s!
Yeah, well, when 4 layer proto costs come down as much as 2 layer have
come down recently, I'll switch for good.
Panelize ;-)
(* jcl *)
--
http://www.luciani.org
> Yuck! No GND plane! How barbaric! How '70s!
Yeah, well, when 4 layer proto costs come down as much as 2 layer have
come down recently, I'll switch for good.
I put a copy here: http://www.delorie.com/pcb/m3a-exp-board.pcb
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I'm working on a simple sram/ethernet add-on card for one of my m32c
starter kits. It's a 2 layer 3.5x4.5 board, 32MHz signalling, and the
power and ground are "tree structure" - i.e. no planes (won't fit) -
with 20 mil traces (signals are 8 mil). Heck power and ground enter
the board about 3" a
Ok, in all fairness, my fault for not specifying the project (not the
furnace controller this time).
I'm working on a simple sram/ethernet add-on card for one of my m32c
starter kits. It's a 2 layer 3.5x4.5 board, 32MHz signalling, and the
power and ground are "tree structure" - i.e. no planes (
DJ -
On Mon, Aug 21, 2006 at 12:56:37AM -0400, DJ Delorie wrote:
>
> 0.1 uF or 1 uF ? Same footprint (0603), the 1uFs are a few cents more
> each (er, ~ 40% more cost for 10x the capacitance).
> Don't know if the 0.1uFs have some benefits inductance-wise or
> ESR-wise, in general.
This is indee
0.1 uF or 1 uF ? Same footprint (0603), the 1uFs are a few cents more
each (er, ~ 40% more cost for 10x the capacitance).
Don't know if the 0.1uFs have some benefits inductance-wise or
ESR-wise, in general.
This question (and those like it) is the topic of constant debate on
SI-LIST. My take-
A more expansive question is about the selection of inductors and
capacitors for power supplies. The issue as I under stand it is that we
put inductors comming out of power supplies to insure a "constant"
current and capacitors are there for a "constant" voltage. In reality
these devices help but
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