Small Electronic Project for Kids – Magic Of MOSFET (MOM)

Here is the smallest circuit that is both interesting and very responsive. It is a very reliable Metal–Oxide–Semiconductor Field-Effect Transistor (MOSFET) based Touch Sensitive Switch.

In this circuit (named as Magic of MOSFET – MOM) I have made a Simple Touch Sensitive Switch using single 2N7000 MOSFET to switch ON and OFF a 3V (white) LED that can be replaced (along with the 330ohm resistor) by a 5 Volt Micro Relay to Turn On/Off 220V load.



Operation of touch activated switch circuit:

The Gate Terminal (G) of the MOSFET Transistor is insulated from the Drain (D) and Source (S), so that it can hold the charge and act like a small capacitor.

To Turn ON the LED using touch switch just place your finger across Gate (G) and the Positive Terminal (A), which will charge the Gate through the finger and the circuit will turn/remain ON as the Gate Terminal will hold the charge. Now to Turn OFF the LED you just have to place a finger across Gate and Source Terminal of MOSFET (marked B) which will discharge the Gate through the finger, and the MOSFET (2N7000) will go into OFF state – turning OFF the LED (or Relay).

For AC Load:

Now to control the AC Load you just have to replace the LED and the resistor with a 5V micro relay. Connect your 220V Load / Lamp to the N/O of the Relay.

Touch Sensitive Switch Using MOSFET

Touch Sensitive Switch Using MOSFET

Components Required:

  • 2N7000 (MOSFET)
  • 330
  • 3V White LED

Other Requirements:

  • One Small Empty Matchbox
  • 9V Battery
  • 9V Battery Connector
  • Small 1inchx 1inch PCB
  • 20cm wires
  • Soldering Iron, Soldering Wire, Wax

Cost of Project: INR 30/- (Including Battery)

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Comments (6)

  1. Tarun Acharya


    The project is simple and useful. It can be used as a project for students of class 9 students. I see even engineering students doing such projects. Keep up your good work.

  2. Martie Homer Tower


    Thanks extremely practical. Will share website with my friends. Martie Homer Tower

  3. Kamila Hasty Bough


    Way cool! Some extremely valid points and good ideas of circuit in this website! I appreciate you penning this post plus the rest of the site is very good. Kamila Hasty Bough

  4. bahis


    When some one searches for a clean circuit on using a Mosfet with excellent explanation I always refer to your blog. Thus Sartaj wants to be available that in detail, thus that thing is maintained over here.

    Norry Donovan Tabib

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