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:
The following photo shows the parts supplied in the kit:
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.
In the main the kit went together well. However the pins of the 555 timer and its socket were badly bent. Great care was needed to bend the pins back to shape without breaking them. It took quite some time to get the 555 to fit into its socket. Another 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:
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:
Square wave
Sine wave
Sawtooth wave
Triangular wave
It will be noticed that the waves are quite noisy. The different types of waves also 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.