Compoment alternatives - woodpecker trem

[Grover]

Hi guys, first time pedal pcb builder and forum poster - I’m starting with a woodpecker tremolo.

R3 calls for a 12K resistor and all I have are 10s and 15s. Which one should I use? Does it really matter in this instance? Why/why not?

The only other part I’m missing is c5. It’s a 220n capacitor and the space on the board looks like it’s meant for a film, but all I have is an electrolytic in that value. Can I use it? Does polarity matter? Why/why not?

Thank you!!!

 

[Grover]

Well shoot. One more.
R10 calls for a 27K - I have a 33k and a 22k, which one?

 

[chris.knudson]

The value of R10 isn't as critical, you can probably use either the 33k or 22k. R3 is more critical in that is sets the voltage that the PF5102 turns the gate on and off. You probably want to keep that as close to 12K as you can. If you have a 10K and a 2K, you could wire them in series (i.e. twist the leads together on one end and solder them -- trim off the excess, and then use the other leads to solder them to the board). It won't lay flat on the board, but that doesn't matter. You can also do the same thing for the 27K using the 22K and a 5K if you have one.

For the 220n capacitor, theoretically you could use an electrolytic, but polarity does matter. Electrolytics are designed to have current only flow in one direction through them. If you reverse the polarity, it will pop -- the bigger they are, the bigger the bang they make. I would recommend getting a film cap, but if you're determined to use the electrolytic, make sure the positive side is the side connected to R7 and pin 2 of the 2N5089.

 

[Grover]

Thank you so so much!
I’m going to series the 12k, put in a 22k, and order a 220n film cap.

 

[Giorfida]

Well shoot. One more.
R10 calls for a 27K - I have a 33k and a 22k, which one?

Measure them with your meter first. Pick the one with an actual value closest to the value you want (most carbon film resistors tend to read on the low side). Or use 4 of them in series/parallel and you’ll likely be dead on

 

[Grover]

Measure them with your meter first. Pick the one with an actual value closest to the value you want (most carbon film resistors tend to read on the low side). Or use 4 of them in series/parallel and you’ll likely be dead on

Thank you, I ended up doing both in series like a teepee as suggested (10+2 and a 5.1+22). I then measured with my meter (which is an old analog one from Sears that used by be my grandpas) and it seemed to get me there in both instances.

 

[Giorfida]

Thank you, I ended up doing both in series like a teepee as suggested (10+2 and a 5.1+22). I then measured with my meter (which is an old analog one from Sears that used by be my grandpas) and it seemed to get me there in both instances.

I always think of things the hard way: 22k+33k in series is 55k. 2x 55k in parallel would be 27.5k, and since carbon films always read a little low, you’d be likely sitting right at 27k. Your way is MUCH simpler!!