electronic doorbell light circuit schematic

Electronic Doorbell Light Circuit

This 6V battery operated doorbell light circuit can be connected in parallel with any existing AC230V doorbell. When anyone push the doorbell switch, the bell sounds as usual and ac mains supply available across the doorbell is routed to the input of this circuit through an opto-coupler(IC1).

Conduction of IC1 triggers a monostable, wired around the good old 555 timer (IC2). As a result the high-bright white LED (D2) at the output of IC2 is switched on for a short time. This circuit is highly useful at night/midnight as it gives sufficient indoor light to help you locate switches for room lamp/porch light, etc. On/Off duration of the LED light can be increased/decreased by increasing/decreasing the value of C2.

The electronic doorbell light circuit is fully safe because it is perfectly isolated from the fatal ac mains supply by IC1. However, keep to avoid accidental contacts with the front end of the circuit, which is directly connected to the ac supply. Use of a good and convenient ABS enclosure is recommended for this doorbell light unit.

Electronic Doorbell Light Circuit Schematic

electronic doorbell light circuit schematic


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  • T.K.Hareendran

    In my reply to Mr.Sivanand, Part number of the recommended opto-coupler is wrongly indicated as NEC2502.The correct part number is PS2506-1.

  • T.K.Hareendran

    During testing,reverse voltage measured across the input of IC1 is well below the value specified by 4N35 mfr.Although I’ve not tested my prototype with the anti-parallel diode,I welcome your comment.Thanks!Further,an ac opto-coupler like NEC2502 can be tried in place of IC1,which obviatesthe requirement of the additional diode.

  • Sivanand.V

    The LED in the opto isolator would fail due to high reverse voltage of the mains, a diode should be added anti parallel with it.

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