Do you recognize this PCB?

[Mark Hammer]

Sifting through my bin of toner transfers, I came across this one.  In most instances, I can either rely on the name of the circuit being part of the toner transfer, or being written on after printing.  But in this case, I guess I fell down on the job.  Judging by the number and size of chips likely involved, I'm thinking it may well be either a synth circuit of some kind, or something using PT2399s.  But after having spent time going through my hard drive, looking for the layout, I've had no luck.  If this image rings a bell with you, let me know.  Thanks in advance.

[ElectricDruid]

I dunno, but that 18-pin chip on the LHS looks like a clue. It's none of my "usual suspects" though, sorry.

[EBK]

Could be a burst box.  Do you have a large coil of copper wire and some lithium-6 deuteride to test this theory?  Sorry, I've got nothing (almost).

A quad op amp at left center there? (Looking at that square pad as a pin 1 and those power rails.)

[Rob Strand]

To me the left hand side is 14 pin, you can see the power pins on 14 and 7.  Perhaps a CMOS gate.  The right hand side could be a quad opamp.  I haven't check the power pins.

[EBK]

To me the left hand side is 14 pin, you can see the power pins on 14 and 7.  Perhaps a CMOS gate.  The right hand side could be a quad opamp.  I haven't check the power pins.

I'm seeing it as 14-pin with power at pins 4 and 11.

[Rob Strand]

I'm seeing it as 14-pin with power at pins 4 and 11.

So do I ... now    I looked at it 10mins ago but I was posting on another thread.  Could have sworn I worked out the power pins but now I see the quad opamp on the left and the right I'm not so sure.

For the right the bottom right pins look like two caps going to ground (maybe).   Pin 5 not connected.  That has to be a non-generic chip.  In fact a PT2399 matches that.

[EBK]

I agree with the pt2399 assessment.  You can see how the +V goes to the +5V regulator (top of the cross shape) before getting there.  This is fun!   Could almost start tracing out a schematic!

[Rob Strand]

I agree with the pt2399 assessment.  You can see how the +V goes to the +5V regulator (top of the cross shape) before getting there.  This is fun!   Could almost start tracing out a schematic!

Yeah, it *is* fun doing electronics detective work.

If someone traced the board it might spark more insight into what it is and perhaps where to look for inspiration.  It could even be "obvious".

One piece of info I was trying to use is the style of the layout, largely 90deg corners.  Who does boards like that on the forum/web?  Also it's wired, no pots mounted to the board from what I can see.

[Mark Hammer]

Just so you know, I'm just as puzzled as you folks.  My own inclination was also that a) it looks like it involves a 2399, and b) I began by asking myself "Whose layout style is this?".  Put those two together, and the companion question is "Who would have come up with a layout for a 2399-based circuit?".  As near as I can tell, there would only be a single 2399 in this circuit.  Were there 2, that might have narrowed down the search space.

I suggested that it might also be a synth-related circuit, but I know that neither Tom Gamble or Motohiko Takeda posted any such circuits, and the style is decidedly not the late great Ray Wilson's, nor is it Anders Bergfors (Bergfotron) or Yves Usson.  And while I have a collection of Japanese circuits, those all predate the 2399 by a few decades, so I can safely rule them out.

Given the costliness of PnP, I only use it when I think it's a circuit really worth making.  So I'm assuming that it isn't a what-the-hell-may-as-well-print-that-one-too circuit.

I think the observation that it lacks pads for mounting pots directly to the board is a potentially useful clue.  Finally, while not any sort of litmus test, when I have a layout for a double-sided board, I will keep the top and bottom printed layouts together.  And this one was sitting all by itself, so I'm assuming a single-sided board.

I sure wish I had something like those huge facial-recognition databases you see in movies where thousands of faces keep flashing past on the screen, until it locks onto one that matches the security-cam footage.  In the meantime, I'll keep looking. 

[Rob Strand]

I sure wish I had something like those huge facial-recognition databases you see in movies where thousands of faces keep flashing past on the screen, until it locks onto one that matches the security-cam footage.

If you took a direct-on photo and converted it to black and white using one of those thresholding/curves tools in paint packages then feed it into google *image* search it would be interesting to see what comes up.   Sometimes google image search can be thrown off by simple things like re-sizing, re-coding.

I did find a site called "music from out of space" (something like that) it was synth related and some of the layouts had the same style.  Maybe it rings a bell with you?

[anotherjim]

The PT2399 is pretty much nailed.
If the 14pin with CMOS power pin positions was a 4016 or 4066 then it could be one of the few PT2399 designs with tails on bypass.
One possible is EchoBase, although the schemes and layouts I found use a pair of TL072 dual amps instead of the quad.

[EBK]

Ghost Echo, perhaps?

Are there just two DIPs on this board?

[Mark Hammer]

I did find a site called "music from out of space" (something like that) it was synth related and some of the layouts had the same style.  Maybe it rings a bell with you?

The Music From Outer Space site is the late Ray Wilson's.  And while he does/did have several projects involving use of a single 2399, the majority of his boards after 2003 or so were double-sided.  He also had a different style, presumably stemming from use of whatever layout software and PCB fabrication service he used.  So, good guess, but not it.

I'm wondering if this is somebody's alternate layout for an Echobase.  But it's not showing up in my image searches.

[duck_arse]

it looks to me as tho the pt2399 is being modulated via pin 2 (nearest pad-pair jumps 0V trace). perhaps an enveloped delay?

[EBK]

Anyone feel like firing up Photoshop, superimposing a PT2399 onto that image, and adding the standard parts to the pins, so we can see what's left?  Looks like we have some square pads to tell us where the electrolytic caps are too.

[MrStab]

i'm late to this party, but could we do this more often? deliberately? winner gets free endorphins

[bluebunny]

I think duck's "pin 2 modulated" and the style (Rick's) gave it away.  It's a "Bigger Angel".



You need to rotate Mark's photo 90^o clockwise to get the match.

[Fancy Lime]

i'm late to this party, but could we do this more often? deliberately? winner gets free endorphins

+1

Anyone feel like firing up Photoshop, superimposing a PT2399 onto that image, and adding the standard parts to the pins, so we can see what's left?  Looks like we have some square pads to tell us where the electrolytic caps are too.

Step 1:


So now we have a numbers and letters to refer to specific pads and traces.

This is great fun! Although I haven't the faintest clue what it could be. Or maybe because of that. Thanks,
Andy

Edit: Aw, rats! Bluebunny solved it. Well, congratulations anyway!

[bluebunny]

P.S. I think the layout above corresponds with this schematic:



(which I found at Fred Briggs' blog here -- scroll down about half-way -- along with a PnP image)

[EBK]

Mr. Hammer is obligated to etch and build this now, right?