IC555 clap switch with timer mini project circuit

This is a special application of IC555 clap switch with timer mini project. It uses a condenser mic to pickup the clap like sharp sound and trigger the IC 555 designed as monostable multivibrator, as shown in the following circuit.

IC555 clap switch with timer mini project circuit
The practically tested circuit of IC555 clap switch with timer for your school or college submission as a mini project

Working of the circuit

The circuit uses one condenser mic to receive the clapping sound and IC 555 is used as one shot timer circuit. When power supply is connected to the circuit, pin-2 of IC 555 is held at +ve supply and so its output at pin-3 remains LOW and the LED D2 remains OFF.

When a sharp clapping sound is produced in front of the condenser mic MIC1, it gets quickly discharged into the base of transistor T1 (preferably BC549B, as tested in our lab), and T1 gets momentarily switched on. So pin-2 receives a short -ve pulse and IC 555 is triggered.

So the output at pin-3 becomes HIGH and the LED lights up. At the same instant, capacitor C1 starts charging through resistor R1. When voltage across the capacitor becomes equal or slightly greater than 2/3 of the battery voltage i.e. about 6V, the output of the IC becomes LOW and the LED turns OFF.

Capacitor C1 gets quickly discharged into pin-7 and the circuit becomes ready for the next clapping sound.

If again a clap sound is produced in front of the mic, same action is repeated.

The circuit is easy to construct even on a veroboard, but the lab tested actual size PCB layout of the circuit is given below.

If you have any difficulty in the circuit, during or after construction, you can contact our expert faculty. You can also refer our most popular article about the details of IC 555. To adjust the timing of one shot multivibrator of IC 555, you can refer to the online IC 555 calculator at this link. For more mini projects of IC 555 refer our special archive.

PCB Layout

IC555 clap switch with timer mini project PCB
Lab tested actual size PCB layout of IC555 clap switch with timer mini project

IC 555 soft touch switch door lock mini project

This is a very interesting IC 555 soft touch switch door lock mini project. It is very easy to construct and useful for your school or college level mini project submission.

The actual size PCB layout of the project is also given here, so that you will be able to construct it within an hour if you have all the components readily available with you.

IC 555 soft touch switch door lock mini project
The simple circuit of IC 555 soft touch switch door lock. Can be constructed within an hour as a mini project

Working

As shown in above circuit, the IC 555 is used as bistable multivibrator circuit. Its pin-2 i.e. trigger pin is held to +ve through resistor R1 and pin-6 i.e. threshold pin is returned to ground via resistor R2. Due to this connection, the IC does not get accidentally triggered or RESET.

The two miniature (soft touch) switches are used to control the door lock condition. Switch SW1 is a LOCK switch and SW2 is the UNLOCK switch.

A heavy duty solenoid SL1 is connected between pin-3 i.e. the output pin of the IC and ground through diode D1. Diode D2 is connected in antiparallel combination with the solenoid to absorb any back e.m.f. whenever the solenoid is deactivated. Thus diode D2 also protects IC 555.

One RED LED is connected in parallel with the solenoid through current limiting resistor R3 to serve as a LOCKed condition indicator – preferably it should be RED in color…!

Now when supply is connected to the circuit, the output of the IC remains LOW and the solenoid remains in UNLOCKed state.

When we press SW1 momentarily, the IC gets triggered through pin-2 as the trigger pin is momentarily grounded. So the IC is triggered and its output at pin-3 becomes HIGH. So the solenoid is activated and it locks the door. The RED LED glows indicating that the door is locked.

Now to unlock the door, press SW2. When SW2 is pressed momentarily, the output of the IC becomes LOW. The solenoid is now pulled back due to its spring action and the door is unlocked.

I recommend to use the battery supply or any full wave rectifier circuit having at least 9V supply. Also use the solenoid with less operating voltage. Here we have used 6V solenoid.

Note: The circuit is practically tested in Vidyasagar Academy laboratory and works very fine. If you notice that when the door is locked and if you switch on/off some other device like a tube light or fan, and the IC gets accidentally triggered or reset, then we recommend to use one small 0.01uF capacitor between pin-5 and ground. This will absorb any noise created in the circuit and will avoid accidental triggering or resetting. For any query, contact us.

PCB layout

This is the actual size PCB layout of the above given circuit.

PCB IC 555 soft touch switch door lock mini project
Actual size PCB layout of IC 555 soft touch switch door lock mini project

Video of circuit working