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.
In the figure we have the typical configuration of a voltage regulator based on an operational amplifier....
This circuit makes use of a 741 single source operational amplifier to measure resistors on a...
Active with the output at the high level, this oscillator was found in November 1984 Radio...