Square wave oscillator Off grid

  • Last Post 20 August 2020
Jagau posted this 13 August 2020

Hi all
I would like to share with you this little square wave oscillator which works the same as a function generator and which operated on battery which can vary from 6, 9 or 12 volts DC according to your needs.

The heart of the oscillator is a TLC555 from the CMOS series which has very low power consumption and is completely different from the old NE555.

It has a 10K potentiometer to vary the frequency from 13Khz to 130Khz and another 5K potentiometer to increase the amplitude of the signal at will.


A drawing of the schematic that I present to you freehand

It can be easily changed by changing a single resistor and a single capacitor.

5 ma on 9 volts battery here

The particularity of this oscillator is that the output voltage changes from positive to negative through zero in the center. This is the AC square wave shape.

Most of these freely sold circuits are above zero volts they are only DC square wave and could not be use for experimentation.

Very low or high amplitude at your choice

This way you are isolated from the electrical network and have greater freedom of measurements without ground return.

 I also hope for those who would like to join us and experiment with us and do not have a function generator, this is the ideal opportunity, easy to assemble and inexpensive.


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Chris posted this 13 August 2020

Hey Jagau,

This is awesome! A very nice, cheap project for anyone to take on that needs a small oscillator!

Thank You for Sharing! This is awesome!

Best wishes, stay safe and well My Friend,


thaelin posted this 16 August 2020

Great addition to the group. Has a very tight transition time but then cmos is very fast usually. Big thanks and will add to the bench soon as can order the tl555.



Jagau posted this 18 August 2020

Hello Thay

Yes the CMOS TLC555 has quite surprising performance especially when looking at the manufacturer's specs:

Minimum and maximum Rise time and fall time are very fast, they approach those of manufacturers of high quality function generators. These are very important parts when making oscillators.

I will be producing an addition to this oscillator shortly
to be continued


Zanzal posted this 20 August 2020

Hello Jagau, the TLC555 is a very good choice. If you only need it to drive high impedance output like most gate drivers then it could be made significantly more efficient (likely less than 1ma at 10kHz).

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