This Public Address amplifier was found in a 1947 amplifier manual. The power supply uses two transformers with two rectifier tubes.
We found this circuit in a 1965 General Electric documentation. The circuit generates synchronized...
Found in a 1968 Ferranti documentation, this circuit can be implemented with modern equivalent...
This circuit with the ULN3784B appeared in the October 1984 issue of Radio Electronics magazine. It can...