We found this circuit in a publication from the 70s, with some configurations that we think are strange, but that can be changed. For example, trimmer C2 in parallel with capacitor C1 has no effect on the circuit and can be eliminated. The circuit can

We found this circuit in a publication from the 70s, with some configurations that we think are strange, but that can be changed. For example, trimmer C2 in parallel with capacitor C1 has no effect on the circuit and can be eliminated. The circuit can be implemented with BC548 transistors for NPN and BC558 for PNP. We recommend caution in the assembly of this circuit, which may not lead to the expected results.