This circuit was found in a Hands On Electronics from the 90s. It turns on an LED to indicate that the phone is in use.
Found in a 90s Practical Wireless, this circuit provides 8 to 10 W of output with a gain of 14 dB....
This crystal-controlled 1000 kHz oscillator was found in 1980s American documentation. The...
This circuit can generate signals from 100 kHz to 1 MHz depending on the L1 coil. For the medium...