whistle light switch circuit schematic

Whistle Light Switch

With this whistle light switch you can turn on and off the lighting installation. The main part of this circuit is the UM3763 IC, produced by UMC. The piezo-ceramic buzzer is used here as a microphone and when it receives a tone frequency between 1.2 kHz and 1.8 kHz, the IC’s output will go HIGH. This means that the light will go ON if it was OFF, or go OFF it was ON.

Light Switch Circuit Schematic

whistle light switch circuit schematic

For light control the UM3763 triggers a triac through T1. The supply voltage is taken directly from the main power supply. D1 and D2 diodes are used as rectifiers, and D3 limits the voltage at 3.9 V. D2 LED is used as an indicator of operating or idle state.

Because the whistle light switch circuit is powered from 220V you need to make good isolation and take good precautions.


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  • Rafa_RGB

    Hi Ogrenero,

    As per datasheet available here:

    Power supply MUST be kept BELOW 5v in order to do not damage the device.

    BTW, the above schematic shows a 3.9v zenner, so it’s perfectly right to powering UM3763 that way.

  • ogrenero

    Hello, I was interested in the construction of his project, but I have some difficulties in its implementation.
    I state that I am newbie in electronics even though I have already completed a number of projects, correctly following the schematic to verify the input voltage on the integrated um3763 I are 15-16v instead of about 3.5 which should be the current working optimally.
    you can have a detailed part list.

  • Alexei

    Is there a minimal time period for whistling or this circuit lights up the lamp as soon as there is a tone within those frequencies?