How to Make a Touch Switch Using One Mosfet





Introduction: How to Make a Touch Switch Using One Mosfet


In many ways, the MOSFETs are better than regular transistors and in the today transistor project

we will show how to make a simple touch switch that will replace the normal switch with the help of

a mosfet transistor.

A touch switch is a type of switch
that only has to be touched by an object to operate. It is used in many lamps and wall switches that have a metal exterior as well as on public computer terminals. A touchscreen includes an array of touch switches on a display.

For this project you will need :


9v battery

12v led strip or 12v bulb


Step 1: Mosfet Transistor

The metal–oxide–semiconductor field-effect transistor (MOSFET, MOS-FET, or MOS FET) is a type of field-effect transistor
(FET). It has an insulated gate, whose voltage determines the conductivity of the device. This ability to change conductivity with the amount of applied voltage can be used for amplifying or switching electronic signals. A metal–insulator–semiconductor field-effect transistor or MISFET is a term almost synonymous with MOSFET. Another synonym is IGFET for insulated-gate field-effect transistor.

The basic principle of the field-effect transistor was first patented by Julius Edgar Lilienfeld in 1925.

The main advantage of a MOSFET is that it requires almost no input current
to control the load current when compared with bipolar transistors. In an "enhancement mode" MOSFET, voltage applied to the gate terminal increases the conductivity of the device. In "depletion mode" transistors, voltage applied at the gate reduces the conductivity

Step 2: Mosfet Transistor Projects

Now we will proceed to the soldering of the wires to the 3 terminals of the mosfet just to be easy when we will make the connection to our switch and put in a small case for future projects.

The mosfet used in this project is IRF z44n a very common transistor

According to the IRFZ44 datasheet this
is a third generation Power MOSFET that provides the best combination of fast switching, ruggedized device design, low on-resistance and cost-effectiveness. The TO-220AB package is universally preferred for commercial-industrial applications at power dissipation levels to approximately 50 W. The low thermal resistance and low package cost of the TO-220AB contribute to its wide acceptance throughout the industry. Specifications: Maximum VDSS : 55VMaximum Drain current: 49A at 250CRDS(on): 17.5mOhmsMaximum power dissipation: 50WPackage: TO-220

Step 3: Mosfet Switch Diagram

You have the diagram on how to connect the wires is very simple just connect the load (in this case the 12v bulb)

to the + terminal of the 9v battery and the -terminal of the load to the middle pin of the mosfet.The - negative terminal of the battery to the right end side terminal of the mosfet.And that's it you have an old-school touch switch.

To activate the switch you have to put your finger on the left end side terminal of the mosfet and the +terminal of the battery.

To deactivate the switch put your finger on the left end side terminal of the mosfet and the right end side terminal of the mosfet or the - terminal of the battery.

Step 4: Diy Touch Switch in a Box

Now just use your imagination and make a box/enclosure to put all the wires and the mosfet transistor you can use old plastic stuff that you don't use any more in the video i did use an old cheap power bank enclosure

but you can use a tic-tac case old hand creme(Nivea) and much more stuff.

Thanks all for reading and see you inside the channel

All the best and use your imagination!



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    Please be positive and constructive.




    I made that switch for switching on/off three leds in a parallel circuit. It switches on/off fine but I have two problems. 1. The leds don’t power on as brightly as without the mosfet. 2. When I turn it off and leave it off overnight I come back the next day and the switch has come back on and lights up very faintly. What is the problem?

    can you make a more in depth tutorial?

    What do you want to know? this is the simplest mosfet effect that you will find

    i would like a schematic for the circuit, if that is possible.

    my class only lets us work with schematics when building circuits

    I understand that the circuit was so simple that it could be drawn on a chalkboard.
    As a retired electronics engineer of 30+ years, may I suggest that a combination of a photo of the completed assembly and a "proper" schematic circuit diagram would be very useful in educating other electronics newbies.
    The photo would show all the wires clearly, and where they went to, and maybe include some little paper labels for clarity. If the construction was to be packaged, an exploded view might make for a better photo.
    The schematic would show pin numbers, voltages, and useful notes for the hobbyist.
    I couldn't work out how the touch switch worked, and think it was due to a capacitance effect or static electricity on the person. A data sheet showing the high insulation of the gate, and the voltage needed to turn it on would be useful. Others commented negatively about the lack of schematic, and I found myself frustrated also. Pictures and talking are ok, but "A schematic is worth a thousand words"

    ps. just noticed your night-light circuit. A good way to combine a photo and schematic in one. For your next version (230V), you may want to include some notes on safety.

    Thanks for the comment, constructive criticism always appreciated.I have more to learn myself i am not here to teach others in a school lecture way i just present some easy electronic projects that anybody can replicate fully functional.Behind all my projects are years of experiments, learning, self-learning and more experiments.I try to make people curious and if they want they can go in depth by themselves.And with the electronic diagrams it's 50-50 yes i can put them along the real ones, but if people reading/watching don't know the symbol for the capacitor, or what means 10k resistor, or Ohm law it's pointless.

    The mosfet its a voltage driven transistor being different from a normal transistor 2n3055 that is current driven, by touching the 2 leads the human body has approx 1M resistance so with 0.00001A(and 9v the power supply) we can activate the mosfet


    Can you send me similar project that can be used in Alternating Current for 230 volts that I can used as switch for normal ceiling lights?



    I am waiting for parts to arrive send me your email and will send all the new projects.all the best

    Great simple and straightforward instructable. Thanks for sharing. I was after a simple project just like this thanks for sharing!

    Thank you, anytime buddy No Skills required electronics projects