Escobedo's PWM!!

[LP Hovercraft]

Those of you who want your axe to sound like an old Nintendo sound effect-look no further!  Is there anybody here who has built it with the LFO addition?  It is so well behaved noise-wise for such a raucous effect.   I was wondering a couple things about the LFO as I cant seem to get it swinging.              
                          1.)  Is ground disconnected from Mr. 40106's pin 12?

                          2.)  The 2N3904 is said to connect to Pin 3, would that be to the .005 mf cap too?

                          3.)  Symptom:  the 10k pot sweeps the range manually, and I can't get the 500K pot to make any noticable differences in the sound.  I believe both pots to be good

This thing would be even cooler sounding if it did the LFO trick.  Cheers

[Tim Escobedo]

1.) Is ground disconnected from Mr. 40106's pin 12?

As depicted, pin 13 is no longer grounded. Pin 13 is the input of one inverter. Any unused inverter should have the input tied to ground or V+. Actually, any unused inverter could be changed into a LFO. I just showed the one at pins 12, 13 for a example.

2.) The 2N3904 is said to connect to Pin 3, would that be to the .005 mf cap too?

Yup. The collector of the 2N3904 should connect to the junction of pin 3, the 500k pot, and the .005uf cap.

3.) Symptom: the 10k pot sweeps the range manually, and I can't get the 500K pot to make any noticable differences in the sound. I believe both pots to be good

Without the LFO at all, the 500k pot should be able to sweep the tone from a fat square wave to a very thin pulse. The 2N3904 is acting as a electronically variable resistor in parallel with the 500k pot.

If the 500k pot makes no change, it may be misconnected. The LFO is a pretty easy one to get going. I'm guessing the output of the LFO for some reason is stuck high. Perhaps you could try getting it to oscillate audibly first by changing the 2.2uF cap from pin 13 to ground to a .1uf and sticking a probe at pin 12. If you can't hear it oscillate in the audio range, something else is wrong... miswired, bad connections, bad parts... on down the line.

[smoguzbenjamin]

Sounds like a fun noisemaker to play with. What's the link, because I can't find your site anymore, Tim. :?

[Ansil]

Sounds like a fun noisemaker to play with. What's the link, because I can't find your site anymore, Tim. :?

http://www.geocities.com/tpe123/folkurban/fuzz/snippets.html

[smoguzbenjamin]

Thanks buddy