This 1924 receiver uses a battery for the tube filaments and a high voltage battery for the amplifier and detector circuit. The speaker is kind of high impedance era.
This VCO makes use of an RC4558 which is an operational amplifier with characteristics close to...
In the figure we have a symmetrical power supply stabilized by a zener diode. Transformer and...
The crystal used in this oscillator can have frequencies up to 30 MHz or more, depending on the...