You often hear people talk about “the right vintage sound” and germanium transistors with mojo. Maybe there is something in it? But if you want to build a boost of the transistor that has been in the drawer since the 70s to get this sound you often encounter problems, npn transistors are much more common today and most modern circuits are designed for such. An older germanium transistor like OC45, OC75, AC126 is pnp. It is not possible to insert one directly into a boost circuit for npn. You can see circuits drawn for pnp but then with positive ground. Then it becomes a problem to connect it with other pedals (with negative ground) from the same DC brick.
BJF Universal PNP Germanium Booster kit solves this problem nicely. It is designed for pnp and it has negative ground. Yes, you can actually run it with pnp silicon if you want. The important thing is that it is for pnp and it has negative ground What is the trick then? Download the manual!
Older transistors can be a bit moody and their properties often differ from one transistor to another. With a trimmer on the board, you can adjust a bias that fits your transistor. The circuit has only a few passive components and a germanium pnp. In other words, BJF Universal PNP Germanium Booster is a fairly easy build and a useful and solid pedal.
The pedal has three knobs, Tone, Volume and Saturation. Anyone who wants can add a fourth bias knob to the pedal but then you have to try out the right value for both the value of the pot and the serial resistor so that the end positions do not become “dead”. Of course, a trimmer for bias adjustment is included. The modification for turning the trimmer into panel control is not included.
The complete kit contains a pnp germanium, OC75 or equivalent, and a transistor socket to test other transistors. All other parts required to complete the pedal are also included. True bypass. 9V battery or power supply.