using an external bias pot with a veroboard layout

[mordechai]

If I want to replace the 8.2k bias resistor with an external 10kB pot, which lugs should I use to send wires to the spots on the board where the legs of the resistor would have been soldered?

[EATyourGuitar]

just pick one middle lug and one outside lug. if you want it to turn the other way, just use the middle lug with another outside lug.

[deadastronaut]

how did we know this was a fuzz face!..?

[mordechai]

just pick one middle lug and one outside lug. if you want it to turn the other way, just use the middle lug with another outside lug.

I want the pot, when turned counter-clockwise, to lower the component value (underbias the transistor) and to increase the value when turned clockwise (to proper or even over-bias the transistor).  So -- this would involve wiring lug two to one hole and lug three to the other, correct?  What do I do with lug one?  Don't I have to tie it/wire it to lug two or can I just let it float?

[EATyourGuitar]

some let it float and some jumper it to the middle. I never really understood how a floating VR can have any affect on anything at all. its resistance is infinity since its insulated by air. there might be someone who thinks it is susceptible  to RFI but I think it doesnt matter. never had a good reason to connect it but I sometimes do.

[slacker]

One reason for connecting the spare lug to the wiper is because if something happens to make the wiper loose connection to the track then, the circuit just sees the total resistance of the pot rather than an open circuit. This could be either a temporary break like with a dirty pot or a permanent failure.

[EATyourGuitar]

good to know, thanks man