This circuit was found in a 1970s General Electric documentation. This circuit already used an emitting LED. The circuit operates at frequencies from 50 Hz to 50 kHz with short pulses
This circuit is from a 1987 American publication called Electronics Handbook. The circuit can be...
We found this circuit in the March 1992 issue of Radio Electronics magazine. The circuit uses an...
When the input voltage is higher than 2/3 of the power supply voltage the green LEDs glows. When...