This elementary receiver with a crystal earphone was found in Japanese documentation from the 1960s. The coil has 60 + 40 turns of wire 28 to 32 in a ferrite rod.
The microphone used in this simple FM transmitter is an ordinary small speaker. You speak in front...
This circuit was found in a 70s American documentation. The operational amplifier supports a modern...
This circuit causes an LED to flash at a frequency determined by the capacitor. The circuit is...