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Title: Phuncgnosis bias voltage problems
Post by: smoguzbenjamin on December 07, 2003, 11:27:21 AM

Hey all!

I put tim escobedo's phuncgnosis on my breadboard this afternoon, but it ain't working. Just a big volume reduction. Anyway I measured the bias voltage first and it read 1.24V dammit :evil:
I did change a couple of parts around, the 680 pF caps are 470pF on my board and I used a 1n4002 germanium diode for D3 and not Si 1n4148.... The 5M resistor is only 3M and I omitted the 1M sensitivity pot... :roll:

Here's the link to tim escobedo's schematic of phuncgnosis:

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

I used the Vb method on the picture. But why am I getting 1.24 volts? It's a fresh battery, so no problems there... What's wrong?

Title: Phuncgnosis bias voltage problems
Post by: Ansil on December 07, 2003, 11:29:59 AM

you are measuring from ground to reference rigt.???

Title: Phuncgnosis bias voltage problems
Post by: smoguzbenjamin on December 07, 2003, 11:38:26 AM

Yup, ground to reference...

Title: Phuncgnosis bias voltage problems
Post by: Joep on December 07, 2003, 12:10:22 PM

It looks like something is loading down the Vref, check for miswiring.

The 1N4002 is a Si diode, so that shouldn't be the problem.

The 470p will change the working point of the filter but that shouldn't cause you problem also.

Good luck,

Joep

Title: Phuncgnosis bias voltage problems
Post by: smoguzbenjamin on December 07, 2003, 12:36:37 PM

I think I've flipped a diode the wrong way round, but I haven't checked yet... Got to wash the dishes tonite :mrgreen:

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DIY Stompboxes => Building your own stompbox => Topic started by: smoguzbenjamin on December 07, 2003, 11:27:21 AM