This circuit is from 1980s documentation. The maximum operating frequency is 3.5 MHz. The current of the LED can be from 0 to 100 mA. The integrated circuits used are from that time.
This oscillator takes advantage of the 2000 ohms headphone inductance as the oscillator circuit coil....
This circuit was found in an 80's Electronic Engineering. The circuit uses a multivibrator with...
Found in a 90s Radio Electronics, this circuit is intended to trigger a relay when the current in...