This 4-voltage power supply using zener diodes has a maximum recommended current of 25 mA. The circuit was found in the May 1966 Radio Electronics magazine.
This interesting source of very low voltage for reference finds applications in the...
This sonic switch, sound relay or simply vox uses a medium impedance speaker as a microphone. The...
Using red LEDs with ignition voltages of the order of 1.5 V we can make a multiple voltage...