Ripples and piezoelectric effects...

This morning I had to spent my time and there was no power at my house. So, I made the dull day kinda exciting by detecting ripples that comes through a 7805 linear voltage regulator. This is the first time I used my DSO Nano v2 to some good work.

The 5V regulator would give out a voltage that would ripple around 5V, and DSO Nano doesn't have AC coupling. So I made an AC coupler myself. A simple 100nF capacitor in series with the probes. The circuit was a 1K resistor across the 5V output. Then I started to observe. My mains have a frequency of 50Hz. And the whole voltage regulator setup is transformer-rectifier-filter-7805-filter. I actually forgot what I put inside the rectifiers so I cannot really write up those here and I am too lazy open the whole casing.

Here are the ripples that I got from my home-brew 5V regulated voltage supply. V(peak-peak) for ripples was about 25mV. And not to mention the frequency of the ripple is 50Hz. One thing to be noted that is the mains is not actually mains, it's a domestic UPS. There was a power-cut and we were running on UPS. And the UPS gives out 50Hz, 220V square wave as the specification says.

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And then I got bored again and I started to experiment with piezoelectric effects in capacitors as Dave said in his post. I hooked up a ceramic 100nF capacitor with DSO probes and whacked it many times and got some shocks. I am putting those here. I will tell Dave (of EEVBlog) that I got these shocks.

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And then experimented with the bouncing patterns of momentary push switches. The switch was connected with pull-up of 1K with 5V. Here is the bouncing I got once after trying it out multiple times. The switch I used was of pretty good quality and didn't bounce at all or my DSO nano was not fast enough to catch any bounce. And this doesn't look anything like bouncing!

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P.S. All the wave captures are done with DSO Nano v2 with BenF firmware. I also noticed that the metal body of the DSO nano did affect the waveforms. When I touched the body, the ripples went to also almost zero. I think it's an isolation problem that happens with the UPS.