freestompboxes.org

Someone has already picked up one of these or has some information. I liked the fuzz mix of this pedal, but I do not find any information about this circuit online. Just a picture of him that does not say much.

great sound....

How does Q1 work here? Looks strange...

roseblood11 wrote:How does Q1 work here? Looks strange...

That's exactly what I said in the thread on Tagboard about this I'd love an explanation for this as well.

This is kind of a wild guess since I haven't really studied fets, but it looks like it might be acting like a noise gate?
I'm basing that guess off of this article which states:

If you leave the Gate (G) of a JFET open, the Drain (D) and Source (S) will pass signal through, as the switch is connected. If you pull the Gate to a voltage less than the Source, the JFET will no longer pass audio signal.

The drain's connected to signal input while the gate is connected to the output of the BJT. So, if the signal isn't loud enough, then no sound should pass?
I haven't built the circuit, so I don't know how it acts, but, like I said, that's my guess.

I believe Q1 is functioning as a clipper, swithing on/off, clipping the negative half of the wave form in response to the signal it's recieving at it's gate from the output of the Darlington collector. The fet source is biased roughly 300mV lower than the gate, which is biased by the voltage at the Darlington collector.

My 2 cents worth....

I made a simuation of this circuit.
I made a short between drain and source and nothing happens the output shows the same signal as before with different input levels.
Now I am confused of that, who could try it with the real circuit?

Manfred wrote:I made a simuation of this circuit.
I made a short between drain and source and nothing happens the output shows the same signal as before with different input levels.
Now I am confused of that, who could try it with the real circuit?

Keep in mind that you will have a very high resistance between the gate and the source (roughly 1M depending on the fet and the gate leakage), this is what biases the Darlington. IMO

The JFET acts like a diode.
The gate-source voltage is allways positive and therefore the channel resitance is very low.
That explains why the short between gate and source has not affects nothing.
I removed the JFET in the simulation circuit, connected the base and the 10kOhms resistor,
added a small-signal-diode between base and collector, and the circuit works in the same manner.
What a supprise.

Oh so it's kind of like a Bazz Fuss type thing but with a JFET? Interesting...