Part #? (ss PCB Layout)? [sdiy] noise source crap out

[Cynthia Webster]

I'm making up a couple of PC boards today and have some spare real estate on
the copper clad board... I thought "hey, there's that neat little noise
circuit that I downloaded the other day from the ASM-1 site"

Then I thought, do I really want to wait to do a PCB layout for it, or just
waste the extra area of copper?

I looked at the ASM site today and saw the close-up picture of the Noise
generator... Looks like a double-sided PCB, (I'm doing single side only)

So then I thought I'd ask if anyone has a single-sided PCB layout for just
that ASM-1 Noise Generator circuit??
(even a funky one from the "testing days")?

It appeals to me - because of the "third" noise output...
We all have White and Pink, but fewer have Red (or is it Blue, noise?)  Low
frequency CV type noise) I'd like some o' that!

order: (1) Quart of Red Noise - please...

Now I see "Oh Great! That's the circuit that just fried on the DIY list!"

I'd still like to whip one up, (Did you find a "better" transistor, or just
use the same one.  BTW the transistor is NOT specified in the .pdf Schematic
that I have - What to use)?   Hmmm....
 


on 3/26/02 10:42 AM, Magus Ship at elmystico at earthlink.net wrote:

> Thanks everyone for the advice on this, I swapped out the transistor for a
> new one and it sounds great! Better than before.
> ----------
>> From: Tim Ressel <madhun2001 at yahoo.com>
>> To: Magus Ship <elmystico at earthlink.net>, synth <synth-diy at dropmix.xs4all.nl>
>> Subject: Re: [sdiy] noise source crap out
>> Date: Sat, Mar 23, 2002, 12:50 PM
>> 
> 
>> Yo,
>> 
>> I don't think the caps are the problem. Here is how my
>> coffee-addled brain would approach it:
>> 
>> Step 1: Check power supplies on the opamps
>> Step 2: Ohm out the ground connections
>> Step 3: Inspect the board for cold joints etc.
>> Step 4: Flex board and listen for output changes
>> --> if you hear changes, re-solder all joints
>> Step 5: If you have a scope, look at outputs of amps.
>> Look for distortion, heavy dc biases, clipping, etc.
>> Step 6: If the opamps are socketed, swap opamps one at
>> a time.
>> Step 7: Swap the transistor
>> 
>> Questions, queries, posers:
>> 
>> All outputs affected? Or just one?
>> Varies after turn-on? Or constant?
>> 
>> Hope that helps.
>> 
>> --TR
>> 
>> *******************************
>> When in doubt, gulp a Hexuccino
>> *******************************
>> 
>> --- Magus Ship <elmystico at earthlink.net> wrote:
>>> "All of a sudden" my homebuilt noise source, which
>>> is based on the
>>> Electronotes and ASM-1 designs has crapped out.
>>> What used to be a rich hiss
>>> has become a futzy stream of what sounds like badly
>>> band pass filtered pink
>>> noise.  Around this time the ground connection at my
>>> power supply became
>>> desoldered (unrelated? related?).  My question is
>>> whether the transistor or
>>> the filter caps to get pink and Random Low Frequency
>>> outputs would be the
>>> problem.  Is it possible that a transistor that
>>> provides good noise can
>>> change or crap out over time?  Or is it more likely
>>> that a cap or a bad
>>> connection in the filters would produce this effect?
>>> thanks as always.
>>> Gavin 
>> 
>> 
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