How to Control the AC Appliance By Simple One Finger Touch

Published by Ubaid Khan on

In this tutorial, We are going to explain a minor project on How to Control the AC Appliance By Simple One Finger Touch.  A touch switch which works upon on finger touch sense between 50 to 90hz frequency. You can control any type of AC and DC appliance by just one finger touch. It’s working without pressing any key. We can perform more tasks and control.

In this project, you will find components, procedure, working to understand better about How to Control the AC Appliance By Simple One Finger Touch. 



R2=500k    (Variable resistor)





C1=0.1uf to 1uf capacitor C2=100uf (15 volt)

D1=Red color LED

D2 = green color LED

TP=touch plate or blade having size 1”x1” ( it remember that this size making problem for sensation to keep on LED by nearing the hand then small and small its size .this (touch plate)blade depend upon on pin #2 and circuit sensitivity.

You can increase or decrease the circuit sensitivity.



Power supply =5 to 6 volt



The NE555 IC pin #2 so sensitive that’s why maybe in the output you see the led or sound oscillation then connect between pin #2 and power supply positive pin a 1M ohm resistor.


In most circuits, the 555 IC work like the pulse generator or multivibrator but here in this circuit it works like one shot means when you touch the(touch plate ) of the circuit and left the circuit or you continue touching plate in both cases it works one time.

Once you touch the plate while it completes its cycle then it works again.

When you touch the plate emit the signal from pin # 3 of 555 IC, and get this signals clock Input of SN7476 IC and change the flip flop current state.

This new state maintains while you again touch a plate.

The RED and Green LED s have connected an output of circuit for checking.

If are not in favor of LED s then you must connect the 5-volt relays for AC fan, LIGHT CFL, or other equipment control till 200watt.

You can provide supply from an adapter or battery of 6v

Or using LM7805 IC convert 9, 12 and 15 volt supply to 5 volts.

Attach a small heat sink to LM7805.

For Relay connection, you must know about the pins of relay and working of Relay?

Relay an Electromechanical small device which uses for automatic AC controlling.

There are 5 pins of the relay.

IN three group of pins the sides pins are for coil supply anode, cathode or +ive -I’ve .this will be 5 volts for relay and must be pure DC.

The center pin is the main pin of interning AC controlling PHASE (LIVE) wire.

The other 2 pins N/C (normally closed)   N/O (Normally Open)

By default center pin connected to the normally closed pin

As the Relay coil energized (mean supply provide) 

The center contacts internally to connect to the normally open pin.

The AC appliances we indirectly controlled by relay using actually we control the main coil of the relay by the circuit.

ICs Configuration and Specification

SN 7476 IC

In this IC use two JK Flip flop work. That’s why it’s called to sometimes dual J-K flip flop .the following show the performance of flip flops in SN 7476 IC.

       INPUTS       OUTPUTS



 Here the “X” mean (Don’t care ) high or LOW both Can come.

 Now I am showing you the pins specifications

Pin noDetailPin noDetail
1Clock no 19J no 2
2Preset noo110Q’ 2
3Clear 111Q 2
4J no 112K no 2
5Vcc 5 volt13=_ volt
6Clock 214Q’ 1
7Preset no 215Q no 1
8Clear 216K no 1


In some time preset say or written to SET and Clear to Reset.

NE 555 timer IC

This is one of the popular timer IC,

It can use as.

  • One-shot
  • A stable multivibrator
  • Pulse generator
  • Time delay circuit

We can use 7555 IC instead of NE 555.

1_ volt5Control voltage
4Reset8+5 to 15 volt


How to Control the AC Appliance By Simple One Finger Touch  Electrical Engineering proect

This is a relay circuit controlling AC appliances such as Lamp, Fan, Drill machine, etc.

How to Control the AC Appliance By Simple One Finger Touch Electrical Engineering Project

Ubaid Khan

hello friends, we are teh team of engineers and blogging is our passion. our team consists of Tariq Naveed, Izhar, and Ubaid