This transmitter for the 3.5 and 7 MHz ham radio was found in a 1950s Japan publication. No information was given on the coils and the power supply.
This circuit provides a reference voltage for calibration. He uses a diode in a small thermal...
This circuit for model making was found in an English documentation. The SCR can be the TIC106, and...
The operational amplifier used in this circuit is no longer very common, but the configuration can be adapted...