Atari Punk Pots

somasix · Joined: Jun 20, 2006 Posts: 11 Location: Brooklyn, NY

Congrats on getting this to work completely. I'm probably going to have to redo the veroboard on mine. My current theory is that all of the pins of the 556 chip are not completely soldered onto the copper, but, because it's soldered to the copper side, it's going to be hard to get to those solder joints. I'll keep you posted though.

Wild Zebra · Posted: Wed Sep 06, 2006 7:59 am Post subject:

microscope · Joined: Jan 09, 2006 Posts: 10 Location: Brooklyn, NY

So after trying this with the 556 chip and not getting it to work Crying or Very sad

, I changed tactics and just finished bebn_bebn's layout with the 2 555s and I'm happy to say it finally works Very Happy

. I wasn't sure if the cut between the two chips (as Uncle Krunkus pointed out) was a mistake or not but I thought I'd try it with the cut first and it works fine.

If I turn both of the pots all the way in one direction the sound either cuts out or turns to very faint static but I don't think that's a problem. I'm just happy it works.

Wild Zebra · Posted: Wed Nov 08, 2006 10:28 am Post subject:

Glad to know you finally got it working. It happens sometimes. I was trying to build a stompbox the other day. The layouts been verified, Il even built it twice. No go can't figure it out. I'm just gonna set it aside for a while.

microscope · Joined: Jan 09, 2006 Posts: 10 Location: Brooklyn, NY

Just one last question about bebn_bebn's layout - would adding an on/off switch be redundant? Since the negative wire from the battery goes through the tip on the output jack, does that mean that the power is off when it's unplugged?

Thanks

Wild Zebra · Posted: Thu Nov 09, 2006 9:29 am Post subject:

Yep, when you plug in a chord it turns on.

bobodamunkey · Joined: Jan 29, 2007 Posts: 12 Location: USA

What's that blob to the left upper left corner of the vero board layout? is that a pot? or a switch. Also, there is an extra plus sign in between the 2 555's. is that supposed to be there? I am so confused!

bobodamunkey · Joined: Jan 29, 2007 Posts: 12 Location: USA

ok , cheesh! the blob is the audio out correct? so there is no volume knob on this one?

choklitlove · Posted: Mon Jan 29, 2007 6:14 pm Post subject:

i guess not. you can easily add a volume pot to any project. for most, a 100K will work. audio, linear, log, A, B, any will do fine, but i would use audio or log taper. just wire the output of the circuit to the 3rd lug, the output jack to the middle lug, and ground the 1st lug. use this as sort of a guideline:
http://geocities.com/worthekik/atari.html

hopefully this helps. good luck!

SineSurfer · Joined: Jan 19, 2007 Posts: 45 Location: Mexico

bobodamunkey · Joined: Jan 29, 2007 Posts: 12 Location: USA

Well, after 3 weeks of BB'ing , pcb'ing and pulling my hair out, i finally got the 556 schematic to work. A note to others who have posted that they couldnt;t get it to work, here are a few things that i screwed up on:

1) i got the wrong pots. The guy at Marvac gave me 500ohms instead of 500K. Not to say it was his fault entirely. I asked for 500K but what i got was different and i should have checked.

2) I got 500K audio tapers not 500K linear. DUH!!!

3) i was unable to find the 10nf and 100nf so i got them from a place online and they were not 50V. That was one problem i also overlooked until Nate from natemc.com helped me troubleshoot. Thanks NATE!!!

I decided to use Nates part list from Mouser.com and finally was able to breadboard and get it working successfully.

One question i do have, is in the schematics provided by http://www.getlofi.com/wp-content/uploads/2006/10/atarilayout.gif

How do you know what voltage to use on the caps? I only know from what Nate used. Did anyone else use the same specs for the caps?

Uncle Krunkus · Posted: Thu Feb 08, 2007 2:18 pm Post subject:

Usually with caps I look at what is the maximum voltage they are like to "see" (usually the supply) and times that by 2. Then get the next available value.

bobodamunkey · Joined: Jan 29, 2007 Posts: 12 Location: USA

ok, so let me see if i have this correct. If i have a 9V power supply, then i multiply by 2 which equals 18 . so i would look for something above 18, like 20V?

Uncle Krunkus · Posted: Thu Feb 08, 2007 5:24 pm Post subject:

Yeah,
It's a "maximum voltage rating" which is the maximum voltage which can be put across the cap before it starts to break down. Just like with a resistor's wattage rating, you can over rate it as much as you like. The only limiting factor is size and price. (ie; in both cases a higher rating takes up more physical space and can be harder to fit onto a PCB, into a case etc. and will cost more, especially with large electrolytic caps)

Gus · Joined: Jul 09, 2007 Posts: 3 Location: UK

I made a build of the dual 555 APC but cant seem to get anything from it; literally no sound whatsoever. I am completely new to this so its most likely something I have done, does anyone have any suggestions? PLEASE! Im really annoyed...

Uncle Krunkus · Posted: Mon Jul 09, 2007 3:52 pm Post subject:

Gus · Joined: Jul 09, 2007 Posts: 3 Location: UK

finally got one oscillator to work by shorting the circuit with my fingers. The 500k pots seem to have little to no effect however, I may be bypassing them with my fingers. I think it needs more work...any suggestions?

Gus · Joined: Jul 09, 2007 Posts: 3 Location: UK

It seems to have gone again, nothing working again, checked the power supply and this seems to be dead, although only with the jack output connected...no clue why. very confused. Just to double check, the 555's are supposed to be on the board side rather than the copper side? Does anyone know of a good APC build because many seem to be yielding problems...
thanks alot for the reply!

Uncle Krunkus · Posted: Tue Jul 10, 2007 5:03 pm Post subject:

I wanted to check that stripboard layout the other day against the original schematic. But I checked Aaron's website, and I can't find it anymore. So if you can find me the schem, I'll check it.

frijitz · Posted: Wed Jul 11, 2007 3:56 am Post subject: big time error in layouts

I just ran into this thread and thought I would have a look at why so many people have had problems. I believe the trouble is that there is an error in the two stripboard layouts people have been using.

The error is that one of the timer reset pins is not connected to the V+ supply, or to anything else, as far as that goes. It's the same error in the 556 layout and the 2x555 layout.

For the 2x555 layout, a jumper needs to be connected from pin4 of the upper device to the + battery terminal. The easiest way to do this is to actually jumper the two pin 4's together.

For the 556 layout, it is pin 4 that needs to be jumpered to the + side of the battery. Note that the layout here ...
http://geocities.com/worthekik/atari.html
has pin 4 correctly connected.

It is not clear exactly what problem leaving the reset pin floating would create, but it could possibly lead to the kind of flakey behavior people have been seeing.

Wild Zebra · Posted: Wed Jul 11, 2007 7:37 am Post subject:

Humm, I've built 6 APC's from the 556 aron nelson stripboard and they all "seem" to work fine. They sound like the sound samples. Albeit, I do get alittle sparking when one of the pots is low, but I heard other people say that. I can not comment on the dual 555. I still have a few unboxed I'll have to jumper with a test lead and see what happens. It clearly is connected to 9V+ in the schem though, good eye.

Wild Zebra · Posted: Wed Jul 11, 2007 7:44 am Post subject:

UK the schem is here http://compiler.kaustic.net/machines/apc.html

frijitz · Posted: Wed Jul 11, 2007 7:46 am Post subject:

frijitz · Posted: Wed Jul 11, 2007 7:54 am Post subject:

Wild Zebra · Posted: Wed Jul 11, 2007 8:09 am Post subject: