This circuit is from an 80's publication. It makes use of small 6 V x 50 mA incandescent lamps. The diodes can be general purpose or even 1N4002. The transformer is 6.3 V with 100 mA or more current.
This circuit is recommended by Texas Instruments in the datasheet of the TL317, equivalent to...
This circuit can be used in alarms, data links or áudio links using IR radiation. The circuit is...
For a maximum current of 50 mA the capacitor must be from 470 nF to 250 V if the grid is 110 V and...