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 simple receiver picks up local MW stations with playback on a small speaker. The antenna must...
This circuit deactivates the ignition system after a certain time when you leave the vehicle. In...
This conventional humidity or water alarm circuit was found in an English documentation from 1974....