We found this circuit in an Australian publication from 1991. It is a kit of the time with input for a guitar pickup. The range is a few tens of meters.
This blinker for LEDs up to 500 mA was found in General Electric documentation from 1970....
This power supply was found in the 1996 Texas Instruments Linear Applications Manual. The circuit...
Using a CA3130 operational amplifier, this circuit drives an LED when the voltage exceeds the...