Gristleizer PCB group buy? Who's interested?

[Taylor]

Yeah, we'll see what comes out of this. My original reason for doing this was to squeeze down the ICs to one quad and one dual opamp. Roy, do you think using the 741s is an indispensable aspect of the sound? I'd be happy to do a redesigned board if there could be some major changes, but if the whole thing depends on the 741s, perhaps the currently-available single-sided board is perfectly adequate?

[Rectangular]

what quad chip would you be using ? a TL074 ?  I imagine, given the tolerance of 741's back in the 70s, just about anything will work or sound the same.

[Skruffyhound]

Hi, I'm in for one board, I'd be interested in the new chip design and tweaks if we get some info through on that. Don't care about the pots PCB mount or Pads. On-board power a "must have".

Anybody pick up on Dan N's comment "No! Don't run the audio in the same chip as the lfo! I speak from experience."
Something we should be worried about?

@Taylor, whats this free cad for mac? + Thanks for taking time to do this for the rest of us

[aziltz]

can someone chime in with what this does "in a nutshell"?  I may be interested.

[Skruffyhound]

There is a link to the original thread at the beginning of this thread, there are sound clips and a build report there, if thats what you were looking for.

[aziltz]

There is a link to the original thread at the beginning of this thread, there are sound clips and a build report there, if thats what you were looking for.

i looked through all that.  nothing with guitar was demonstrated and it all sounded like synth-oscillation and such.

I was hoping this was like an LFO-Filter or something

[jacobyjd]

There is a link to the original thread at the beginning of this thread, there are sound clips and a build report there, if thats what you were looking for.

i looked through all that.  nothing with guitar was demonstrated and it all sounded like synth-oscillation and such.

I was hoping this was like an LFO-Filter or something

You sure you looked through all that? I recorded the clip with my Telecaster>Tube preamp>sound card.

An LFO filter is half of it. The other half is a radical tremolo.

[aziltz]

sorry i meant that i looked through the commercial version by EA or whoever

[jacobyjd]

sorry i meant that i looked through the commercial version by EA or whoever

Ah, then you need to check out the thread that started this one: http://www.diystompboxes.com/smfforum/index.php?topic=79078.0

[Taylor]

what quad chip would you be using ? a TL074 ?  I imagine, given the tolerance of 741's back in the 70s, just about anything will work or sound the same.

I'd lay it out for the generic quad opamp pinout. TL074 is my goto quad opamp, but the LM324 and probably others have the same pinout, so people can experiment if they want. Thanks for your comment, it's what I assumed, but I wasn't sure.

Hi, I'm in for one board, I'd be interested in the new chip design and tweaks if we get some info through on that. Don't care about the pots PCB mount or Pads. On-board power a "must have".

Anybody pick up on Dan N's comment "No! Don't run the audio in the same chip as the lfo! I speak from experience."
Something we should be worried about?

@Taylor, whats this free cad for mac? + Thanks for taking time to do this for the rest of us

Yes, I did hear this and responded that I would put the LFO+waveshaper in a quad, and the audio opamps in a dual, so they'd be separate. There's still the matter of "ticking LFO" to deal with, and I'll read up a bit on that. I know about not having right angle traces, but I'm not sure what other tricks there are to avoid this. Do you guys need a blinking LED? It's my understanding that having a rate LED can create ticking.

The free CAD for Mac is called Osmond. I haven't done anything with it yet, but it looks good, and is the only free CAD for Mac I've found, so it's certainly better than nothing at all.

http://pages.swcp.com/~jchavez/osmond.html

[jacobyjd]

Taylor, did you read the comment on the gaussmarkov project page regarding the rate LED? If not, you should check it out. I get no LED noise using a transistor to switch the ground of the rate LED. It's crude, but simple, and it works.

[Taylor]

No, I didn't see that until now. I hadn't read the comments.

"From IC1 pin 6 I have another
transistor rigged as a follower with a LED plus load in its collector to +9V and its emitter grounded. 6k8 between its base and IC1 pin 6. This gives a flashing indication of the rate. Crude but maybe useful."

I'll implement that.

[Ripthorn]

Another way to help prevent LFO ticking is to use a capacitor to ground on the LFO out.  This will make a square pulse a little less square, but will also reduce the ticking, as will using a low power opamp.

[Taylor]

Roughly what value of cap would you recommend?

[R.G.]

My original reason for doing this was to squeeze down the ICs to one quad and one dual opamp.

My experience has been that I get more compact and orderly layouts with better signal flow by using only duals, not quads. In my mind this is because the two outputs of the dual are on the same end of the package, while the quad has outputs in all four corners. Sometimes it doesn't matter, but the extra freedom of being able to point the outputs all in the same direction has generally more than made up for the price of two more power pins. And  in this case, the extra package may provide some signal isolation.

You might want to think about it.

[Ripthorn]

Roughly what value of cap would you recommend?

I think I used something like a 10uF electrolytic, though I am not positive on that.

[jacobyjd]

This will make a square pulse a little less square

This would concern me if it's possible to detect it audibly--if you implement this cap, please make sure to add a note mentioning that it's optional, and what effects it might have.

The square wave LFO shape is one of the most useful parts of the circuit, and if you lose that all-on/all-off ability, it would detract from the purpose of the effect, IME.

The LFO should have very minimal ticking, if at all, if the layout is done right. Mine ticks just a little at the most extreme bias setting, but it's barely noticeable.

Anyway...like I said...the OPTION to add that cap is a good idea, just make sure to note it.

[Taylor]

Good idea, it should be jumberable if people want to.

[jacobyjd]

Good idea, it should be jumberable if people want to.

I think you could just leave it out, since it goes to ground.

...in other news, I'm generally of the mind that everything should be jumberable. I recently jumbered over to the store to buy some turnips.

[Rectangular]

RG is probably onto something with regards to using duals instead of quad+dual. quad stuff can get messy fast.

maybe its just me, but I'm not thinking about this projects in terms of nice, clean, high fidelity audio. its the gristleizer. plus, its a practical electronics circuit, I imagine you'd have to go out of your way to make it sound wrong, they really DIY-proof their stuff

actually, does anyone on this forum have any Practical Electronics magazines ? I came across some a couple of weeks ago by pure chance, and scooped them up. they're amazing. completely unlike the DIY magazines that were sold around the same time (1950s-1970s) in north america (and usually heavily reliant on Radioshack parts)