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I've been trying out building a distortion pedal.
The simple one I have been working off has a single silicon transistor with a 2M resistor between the collector and base of the transistor. It also a diode clipping stage.
I was looking at a second simple project which also uses a single transistor, but this one has a diode (IN914) between the collector and base of the transistor rather than a resistor.

Quite simple and cool etc, but I would like to know why you'd use a resistor rather than a diode at that stage (or vice versa).
Cheers

It sounds like different biasing arrangements. The resistor is bleeding off a bit of collector/Vcc current for the base to set its bias point (usually slightly-on). Using a diode is a bit unusual in this situation - hard to say without seeing both schematics for comparison, but a diode would put the base at 0.7-1.0V less than the collector. Not sure what that means without seeing the circuit setup, but keep in mind that Vbe must be >0.7V for the transistor to not be fully-off (cutoff) and the Ve is usually much less than Vc except at saturation (fully-on). So it'd probably be biased pretty hot.

RectifiedAmps wrote:It sounds like different biasing arrangements. The resistor is bleeding off a bit of collector/Vcc current for the base to set its bias point (usually slightly-on). Using a diode is a bit unusual in this situation - hard to say without seeing both schematics for comparison, but a diode would put the base at 0.7-1.0V less than the collector. Not sure what that means without seeing the circuit setup, but keep in mind that Vbe must be >0.7V for the transistor to not be fully-off (cutoff) and the Ve is usually much less than Vc except at saturation (fully-on). So it'd probably be biased pretty hot.

Thanks for the reply - I'll have to go away and figure out what it means, but I am getting there
FYI - the two pedals are the projects 1 and 2 here: http://tonefiend.com/tonefiend-diy-club ... resources/
Here are partial schematics attached

Ok, keep in mind each schem uses a different transistor - the 2N5088 looks like a step up in terms of gain, compared to the 2N3904. So the associated circuits might not be identical, strictly speaking. However, we're talking about a distortion pedal here so I'd just try it both ways and see what happens. Even if you burn up the transistor (not too likely given it's only a 9V supply) you're only out of pocket by 50c tops!