Three Flashing LED Doorbells For The Hearing Impaired


Posted on Feb 6, 2014

When the push switch is operated - the buzzer will sound and the LEDs will begin to flash. For the hearing members of the household - the buzzer acts as a regular doorbell. It also re-assures the visitor that the doorbell is working. When the push switch is released the buzzer will stop - but the LEDs will continue to flash. The length of time the


Three Flashing LED Doorbells For The Hearing Impaired
Click here to download the full size of the above Circuit.

y will go on flashing is set by the values of R2 & C1. With the values shown in the diagram - the LEDs will flash for a further 30 seconds or so. If you make R2 a variable resistor, you can adjust the time period. If you want longer than 30 seconds - increase the value of C1 or R2. The last circuit will flash up to two groups of 3 LEDs in tandem. This circuit will flash the two groups alternately. The alternate flashing creates the illusion of movement - and makes the display more eye-catching. Note that - although I`ve drawn the two groups of LEDs side by side - the individual LEDs can be mounted in any pattern you like. The main difference between this circuit and the last one - is the addition of the two transistor switches. The switches will each flash up to 15 groups of 3 LEDs. And - because they are getting power directly from the battery - the LEDs will glow at their full brilliance. The Support Material for these circuits includes detailed circuit descriptions - and all the information you need to adapt them to a different supply voltage. Link




Leave Comment

characters left:

Related Circuits

  • New Circuits

    .

     


    Popular Circuits

    Negative Voltage Generator Schematic
    Timing-threshold-and-load-driver
    DTMF Receiver IC MT8870 Tester
    Audio and Video signal Distribution Amplifier circuit
    TPS3803G15 Single Voltage Detector
    Touch Switch And Delay Circuit
    ADJUSTABLE SIREN
    JS88 holiday lights IC circuit
    Resistive neutral leakage protection circuit
    Nine-digit password composed of the controller circuit diagram CD4017



    Top