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Can I omit LOW pot on GreenBean??

Started by diegoyl, July 16, 2020, 05:04:11 AM

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diegoyl

Uh oh, so I'm making a Green Bean but I decided I only wanted the 3 typical pots and left out the LOW pot. I had read on the Pork Barrel that its BLEND pot could be omitted without any other changes and I assumed the same would apply for the Green Bean. I still don't fully understand schematics, if the pot isn't there will it be like a break in the circuit or does it continue another way?

(I am also missing a Si transistor and I currently just have some wire in its place which is probably the reason why the pedal isn't working right now, but I'm still curious about the omitted pot)!

mjg

I'd say leaving it out is fine.  It's basically altering the capacitance that you get with c4 and c5 in parallel.  If you wanted to not use the pot, but have the equivalent of the pot at the 12 o'clock position, I'd put a 10k resistor in its place, between pins 2&3 of the missing pot. 

If you do leave the pot off altogether, you could also omit c5, and use a different value for c4 depending on your taste. 

And yeah, putting a wire in instead of a transistor is most likely why it's not working.  Once you fix that up, you can experiment with the pot. 

diegoyl

Oh ok so from what I understand the capacitors (c4,c5) are setting the range of clipped frequencies and having them in parallel is already the stock version so I just need the resistor to connect it to the rest of the circuit?

So if I leave the holes for the pot empty would the circuit just skip over those capacitors or would they still be doing something? And if they do get skipped is there something else that is setting the range of clipped freqs?

Also, how much of an effect would the value of the resistor have??

(sorry for so many questions, i now regret not paying attention when they taught circuits last semester :'( )

mjg

If you leave the pot holes empty, the circuit will skip C5.  C4 will still work. 

The idea of the pot is that you can vary the value of the capacitance in that part of the circuit.  If the pot is full clockwise, there is no resistance between pin 2&3, so you effectively have C4 and C5 in parallel, so the overall capacitance is 47 + 150. 

If you leave off the pot, then C5 has nothing connecting it, so it will have no effect...and you end up with capacitance being just the value of C4, which is 47.

So various values of resistors in there will get you somewhere between 47 and 197n capacitance I think.  Putting a simple jumper wire in the pot pins 2&3 will be the same as if the pot was fully clockwise. 

Anyway, if you don't want the pot, leave it empty, and I'd suggest put in a socket for C4, and try a few values between 33-220n, and see what you like best.