Found in old documentation, this source uses an integrated circuit from that time, which is uncommon nowadays. The power source has a ripple below 1 mV.
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...