Phase Evolution voltages

Started by gutsofgold, September 26, 2009, 10:25:22 PM

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gutsofgold

I just built the Phase 45/Phase Evolution. With the mix knob all the way up I just get my unaffected bypass signal. As I turn down the mix it just keeps getting quieter. With the mix all the way down I can hear the phase "pulses" and can even adjust them with the speed knob. If I strum hard enough and listen hard enough I can hear the effected signal and it's pulsing just fine. It's just really really really quiet.

Battery 8.2v
VRef 4.6v

I'm getting about 7.2v on PIN 1 of IC2 (RC4558). I know this can't be right and can't seem to figure out why it's so high.

Heres my transistor (2N5458) voltages

Q1 G - 2.6v
     S - 4.6v
     D - 4.6v

Q2 G - 2.5v
     S - 4.6v
     D - 4.6v

frequencycentral

#1
What layout did you use? Did you build it with 2 or 4 stages? I can crack mine open for voltages if it helps, though it would appear to me that if the problem is around the Mix pot and the effected signal your issue must be somewhere around the third opamp - or maybe the way you have configured the Ratio switch.
http://www.frequencycentral.co.uk/

Questo è il fiore del partigiano morto per la libertà!

R.G.

Quote from: gutsofgold on September 26, 2009, 10:25:22 PM
I'm getting about 7.2v on PIN 1 of IC2 (RC4558). I know this can't be right and can't seem to figure out why it's so high.
Well, that voltage comes from one of two places: inside the chip or outside the chip. I'd suggest
(1) reading the Debugging Thread: What to do when it doesn't work and following the instructions. As I keep saying, there is more to that than simply measuring voltages. F'rinstance - is the voltage the opamp is being fed on pin 3 telling the output pin to go high? Or is the output pin being told internally to be the correct voltage, in which case either the opamp is dead or something outside the chip is pulling it high. In addition to doing the obvious thing of making it easier for us to help you, it also forces you to think about what's going on and where it could come from.
(2) following the advice on the Debugging Thread, as closely as you can

From simply being told a circuit has little or no output, and that its output pin is outside the normal range (which I find by reading the datasheet foir the part), my first guess would be that the circuit is being told to do the wrong thing by its bias circuit.
R.G.

In response to the questions in the forum - PCB Layout for Musical Effects is available from The Book Patch. Search "PCB Layout" and it ought to appear.