Designed for the audio track, this circuit was found in a Popular Electronics from the 90's. Other operational can be used and R7 can be 470 k. The frequency is 1 kHz.
This circuit is from a technical documentation from Motorola from the 70s, and for this reason it is...
We found this circuit in a 1976 documentation. The FET can be BF245 or MPF102 and the power supply...
This miniature railway control circuit was found in an English documentation from the 1980s. The...