Found in a 73 magazine for radio amateurs of the 90s, this circuit provides a 2 kV voltage with 7.5 mA of current for HeNe laser.
This voltage controlled oscillator uses a varicap to change the frequency. Usin a 100 turns coil...
This circuit was obtained in a documentation from the National Bureau of Standards of 1968. The...
This circuit turns on your car's backlight when a vehicle coming from behind gets too close to it...