Computer Hardware

How to Make a Touch Switch Using One Mosfet

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HOW TO MAKE A TOUCH SWITCH USING JUST ONE MOSFET TRANSISTOR

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 :

  • mosfet
  • 9v battery
  • 12v led strip or 12v bulb
  • wires

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 provide the best combination of fast switching, ruggedized device design, low on-resistance and cost-effectiveness. The TO-220AB package is universially 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)

  • Batt + ---->Load ----->Middle MOSFET
  • Batt - -----> Right MOSFET
  • To Turn ON : touch Left MOSFET to Batt +
  • To Turn OFF: touche left MOSFET to Batt -

to + therminal of the 9v battery and the -therminal of the load to the midle pin of the mosfet.The - negative terminal of the battery to the right end side terminal of the mosfet.And thats it you have a old school touch switch.

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

To deactivate the switch put your finger between 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 dont use any more in the video i did used an old cheap power bank enclosure

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

Source : http://www.instructables.com/id/How-to-Make-a-Touch-Switch-Using-One-Mosfet/?utm_source=newsletter&utm_medium=email

https://www.youtube.com/channel/UCPjqH3HfNA4Shttkx...