Digital Touch Sensor Using LM358




About: IoT Related Projects

Sensors are the best thing to work around with DIY electronics and this is the second instructable of a series of instructables which creates different sensors compatible with various microcontrollers. In the previous instructable I showed you how to build a digital tilt sensor. In this this instructable I'm going to show you how to build a Touch Sensor. This has various applications such as Touch Controlled switches, doorbells, etc.

This instructable will require soldering skills it is easy to learn to solder and there are various YouTube videos that show you how to do that.

Step 1: Tools and Components

Here is a list of what you need to get started with this instructable.

Step 2: Circuit

The Circuit is quite simple, the heart of the circuit is a LM358 IC, this IC is used to detect when the copper plate is touched. The copper plate is a small block of PCB which is used for etching out circuits. The LM358 has a voltage range of 3V to 32V, which can be easily powered with most microcontrollers.

The 10K pot can be used to change the sensitivity of the circuit, if the led remains ON even without touching the plate vary the pot until the LED turns off.

Step 3: Going Further

If the LED doesn't stick to the Copper plate, use sandpaper or a file to make the surface rough and then flux to stick the soldering wire onto the board.

After you have tested out the circuit on a breadboard next you can build a PCB out of it, there are two ways you can do that one would be to build a arduino shield and another would be to make tiny PCBs that could plug into a breadboard a arduino prototype shield.

2 People Made This Project!


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  • Make it Glow Contest 2018

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7 Discussions

Nic -W-/

Question 3 months ago

Sir, Where should i add extension cable in circuit if i wanna use it for Arduino.

So my Arduino could get Input from that Circuit, Thx sir


5 months ago

Hi. You put on the project list a 10k trimpot (103), but in the project mounted on the protoboard, you put a 100k pot (104).

Please ... which one is the correct one?

And I used both pots .. both 103 and 104. I did but it did not work.

Thanks !


7 months ago

Made it, but not working as expected. Help/Suggestions are greately appriciated

Techno craft

1 year ago

how you made the copper plate, and what terminals do it have

1 reply

1 year ago

Nice project, but how does it work?

Could it be used with a transistor to switch on a mains powered light ?

Cheers ........