Pulse Generator Module Kit

This kit contains parts to build a pulse generator that can generate square, sine, sawtooth and triangular waves with varying duty cycles. The type of wave is selected by means of a jumper while duty cycle is controlled by a trim pot. The frequency cannot be changed. Pulses are generated using a 555 timer.

As ever, the kit came from AliExpress:

Pulse generator kit - advert

The following photo shows the parts supplied in the kit:

Pulse generator kit - parts

The kit as built can be seen in the next photo. Power input and pulse output are connected via female DuPont sockets. The photo shows DuPont cables plugged into these sockets.

Pulse generator kit - completed

The kit went together well, although the IC socket has its pins badly bent out of shape and care was needed to bend them back to shape without breaking them. The same problem applied to the 555 timer chip which took some time to make fit into the socket. The only other problem, which could have been a show-stopper, was that the supplied jumper was broken. Luckily I'd just bought a pack of suitable jumpers, so one of those was used. That explains the colour change of the jumpers in the photos!

I tested the output using my oscilloscope:

Pulse generator kit - completed and generating a square wave.

Each pulse type was tested at the full range of duty cycles. Screenshots of each wave form as displayed on the oscilloscope can been seen below:

Pulse generator kit - oscilloscope screenshot: square wave.

Square wave

Pulse generator kit - oscilloscope screenshot: sine wave.

Sine wave

Pulse generator kit - oscilloscope screenshot: sawtooth wave.

Sawtooth wave

Pulse generator kit - oscilloscope screenshot: triangular wave.

Triangular wave

It will be noticed that the waves are quite noisy. The different types of waves have markedly different amplitudes.

I found this kit particularly interesting to build, partly because I'd just acquired my first oscilloscope and wanted something to test it with. In fact I'd been putting off building the kit until I'd got an oscilloscope because there was no way to know if the kit worked without a scope!

Will I use the finished product? I'm not sure because (a) the output is so noisy and (b) the frequency is fixed. I reckon I'll buy a cheap ready made pulse generator and compare the results.

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