Hi guys, I am just transitioning from (guitar) pedal kit building to putting it all together myself. Not a huge leap, but given I have extremely limited electrical knowledge my confidence level is low. My first solo project is to build a Tonebender Mk1 clone, and there is a fine pcb available on this site together with the build docs. However, I'm confused regarding PNP and NPN germanium transistors, and which I would use if I want the pedal on my regular (centre-negative) pedal board. The transistors recommended on this site are PNPs, and the build has a TC1044SCPA charge pump (no idea what it is but it could be relevant!...) - does that sound ok for my needs or is there something else I should be considering? Many thanks in advance.
TONEBENDER TRANSISTOR POLARITY
- Thread starter raslo
- Start date
Simply put, you can use the pedal with PNP transistors & use standard Boss style power supply & daisy chain the pedal!
Feral Feline
Well-known member
SOCKET YOUR TRANSISTORS!
At the least.
If you don't have a breadboard, you can put sockets on the PCB for the transistors and a few of the other components both feeding signal and sipping signal off of the transistors. Sockets will allow you to try different transistors and some of the other components, which will allow you to dial in different resistance and or capacitance — once you fine tune the circuit and have the right leakage, then you can solder the components into the sockets — but leave the transistors fully socketed or only solder in the middle leg of the transistor so you can replace transistors easily.
Some people here don't like socketing transistors, but doing so prevents heat damage to transistors from soldering; soldering in just one leg of the transistor helps minimise the chance of heat damage. Use an alligator clip on the transistor leg(s) between the solder point and the transistor to help dissipate heat.
At the least.
If you don't have a breadboard, you can put sockets on the PCB for the transistors and a few of the other components both feeding signal and sipping signal off of the transistors. Sockets will allow you to try different transistors and some of the other components, which will allow you to dial in different resistance and or capacitance — once you fine tune the circuit and have the right leakage, then you can solder the components into the sockets — but leave the transistors fully socketed or only solder in the middle leg of the transistor so you can replace transistors easily.
Some people here don't like socketing transistors, but doing so prevents heat damage to transistors from soldering; soldering in just one leg of the transistor helps minimise the chance of heat damage. Use an alligator clip on the transistor leg(s) between the solder point and the transistor to help dissipate heat.
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woah - thanks for the heads-up. I get the gist of the caution, let me do my google homework see if I can figure out how such selection is carried out. If (read "when") I hit a brick wall I'll be back, cap in hand, for advice! Cheers
sounds like a reasonable plan. I've actually ordered a breadboard, it was quite cheap, but I was thinking I'm not likely to get a huge amount of use out of it, so your suggestion seems a good option. After JamieJ's comment I've been trawling the internet about transistors - I didn't realise just how complicated it is. I was aiming for the 'original' specs of OC75 and 2G381 - these things are quite elusive, and what's out there is very expensive. Given I am very much a beginner I thought I'd use the breadboard with some of the cheaper (Russian?) alternatives, play around with some variations without breaking the bank.
