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door timer

Door Timer Circuit with Alarm

We are in a digital era! Now we can add some intelligence to our doors and gates without too much investments. Just assemble this little door timer circuit built around a few cheap and simple components and link it to any door/gate as per your requirement and taste. If the door/gate remains in open condition for a prefixed time an acoustic sounder starts beeping to raise an alert. Enough?

At the heart of the circuit is CD4060, which is a 14-stage ripple-carry binary counter/divider plus oscillator. Here CD4060 is configured as an independent timer. In standy by state, ie when switch S1 is in closed condition, the reset terminal ( pin12) of CD4060 is at a high level and the timer is in inactive mode. When the door is opened, S1 also opened as per the mechanical arrangement and CD4060 gets activated.
After a short period,transistor T1 conducts to power the active piezo-sounder. Red LED in parallel with the piezo-buzzer also lights up instantly. When the door(and hence S1) is closed, circuit returns to standby state automatically.

The open door alarm circuit works off 9V (PP3/6F22) battery supply. Assemble the circuit on a small PCB and enclose in a plastic box of appropriate size. Mount the switch S1 in the door/gate frame and connect it to the circuit through external cable. If possible use a key-lock type switch for power on/off function (S2).

Note: Preset delay time can be changed by changing the value of timing resistor R3. SK1 is an optimised connection terminal for attaching a standard 6-9Volt electromagnetic relay.

Door Timer Circuit Schematic

door timer schematic

4 Comments

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  • nestor villanueva

    the time delay is working only if the door is going to be open.how about if i am going to leave the house and close the door, is there preset time delay also and how long (time) can be activated? thank you for this is an interesting design.

  • taylor

    is there something afforable i could buy that would do the trick as I do not have the time or knowledge to assemble this …i am adding schlage keyless levers on two doors and do not want employees leaving them open

  • jim montano

    sir what is the use of SK1 in your circuit diagram.. pls elaborate… thanks..

    • flower

      when this switch is closed it leads to the completion of the circuit thus the buzzer beeps and when the switch is open the door is closed and no buzzer sound comes

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