The Talk-a-lizer experiment.

[deadastronaut]

^ cheers man, i'll see what he says...still waiting for a response.

[azrael]

I just remembered this great pedal design today, any tips on where to get a good pot for the dual ganged wah pot? Did you just machine the shaft with a dremel or something, to make the gear fit?

[digi2t]

I just remembered this great pedal design today, any tips on where to get a good pot for the dual ganged wah pot? Did you just machine the shaft with a dremel or something, to make the gear fit?

I used the Omeg conductive plastic dual gang.



I got them off EBay. I used the Dunlop gear version with the flat, filing the pot shaft a bit at a time until it fit. I then used a Dremel with a very thin cut off blade to score the end of the shaft for the circlip. Then, just cut off the excess.

Look through the Colorsound Vocalizer thread, there should be a pic showing the Omeg pot installed in there.

[azrael]

Cool, thanks. What wattage rating did you get? Just want to make sure I get one that's about the right size.
It seems that the shaft length and diameter is the same, but still, hehe. Can't hurt to be safe.

[digi2t]

They are 1/4 watt. Plenty for this application. I believe that is the only wattage they have in this model. 

Here is some more info;

http://cpc.farnell.com/1/1/29625-pot-dual-gang-lin-22k-pc2g16eco22ka-omeg.html

[azrael]

They are 1/4 watt. Plenty for this application. I believe that is the only wattage they have in this model. 

Here is some more info;

http://cpc.farnell.com/1/1/29625-pot-dual-gang-lin-22k-pc2g16eco22ka-omeg.html

Okay, yours are linear. That clears it up. eBay has some, but there was also a 1/8W one. A little expensive, but I'll probably still do it. Pretty cool sounding pedal.

[drummer4gc]

Want!

Any thoughts as to how the sound would change subbing a common silicon pnp for the ac128 and an electrolytic in place of the tantalum? Gonna try to do this with parts on hand.

[digi2t]

Want!

Any thoughts as to how the sound would change subbing a common silicon pnp for the ac128 and an electrolytic in place of the tantalum? Gonna try to do this with parts on hand.

Don't use a silicon in place of the germanium in this circuit. Leakage and gain are not important here, since the transistor is being used for switching. Any germanium transistor will work well. It has more to do with the knee in the change of frequency when going from the "Y" to the "O". A silicon transistor will give you a very hard switch over, and is not as smooth as a germanium.

I tried both, and germanium is much more natural sounding. This is a perfect circuit for using that germ tranny that just won't cut it in a fuzz circuit. Cheap Russian tranny will be fine.

As for the tantalum cap, that was spec'd in the Talking Pedal schematic. A 4.7uF bipolar should be fine here.

[azrael]

Good to know about the Germie.

Working on a version using an LM13700 instead, since CA3080 are scarce. I'll post a schematic later.

[azrael]

I'd appreciate a second set of eyes, good people of DIYSB.

[digi2t]

Here's my version, which I built from;



Compare away, and let us know how the LM13700 works out. A video demo would be great.

[azrael]

Will do. Going to get a Peak Atlas DCA this week so I can rummage through my local shop's germaniums, hehe.

[digi2t]

Will do. Going to get a Peak Atlas DCA this week so I can rummage through my local shop's germaniums, hehe.

Like I said, don't go crazy looking for "The One", any germanium will work, even a leaky one. I tried a number of different ones, not even testing them, they all worked. I ended up using a cheap Russian MP20B, only because I could save my good germ for something else.

[azrael]

Not doing that at all.
I have a little stock pile of Germies, but most of them are already arranged into sets. Most of the single ones I have are NPN, so no good for our purposes here.

My local shop just promised to hold old their old stock transistors on a shelf for me, and hide them from the guy doing Creepy Fingers FX lols, so I've been meaning to get some anyway.