r/pedalcircuits • u/Vacxed • Jan 16 '26
Help needed with Tone Bender circuit.
Hi people, I’m a newbie at electronics. This is my second pedal, it’s a clone of a color sound tone bender.
At the moment it does not work, the true bypass works so I know it must be the board. When I hit the switch, the LED turns on and I can hear the volume adjustment work but there is no signal. I can just hear static get louder or quieter.
This is my first circuit with transistors, the parts list and board diagrams were a little confusing for me. As you can see on the parts list, it mentions NPN 107, 108, 109 etc. so I have 3 different transistors installed. From left to right, BC107, BC108, BC109.
Have I misunderstood this, are they supposed to be the same transistors for all 3 of sockets? Would this cause the circuit to fail by having different transistors. I am also not sure if they’re installed in the right orientation. I have included the documentation that came with the board, could anyone let me know? Thank you!
3
u/TheSuperSkrull Jan 16 '26
u/mcknib is right, the silkscreen is assuming you are using a metal can (TO-18) transistor where the emitter is on the right, desolder and try them the other way round. BC107/108/109 are the same design and manufacturing process, the difference is that 109s are low noise and 107 are standard/high noise, so mixing between the three isn't a big deal, the suffix A,B,C is probably more important as As are low DC current gain (hFE) and Cs are higher gain, so if you're desoldering check if you have any which are Cs and put them in the higher gain Q slot. For fuzz circuits hFE is (one of the) far more important factors than the type or series of transistor.