I have got a function generator and power supply for $30 total.

The generator works great, but power supply was kind of weird. It was only adjustable when I did it really, really slowly. Once I tried to go faster, it was jumping to 1 then back to 0 then to 1 then back to 0. Yes, it was usable in general, but for a impatient guy like me it was a torture.

So I took it apart. There was a rotary encoder that did not click. It was just rotating smoothly like a potentiometer. This is clearly not what rotary encoder supposed to do. I decided, that I will likely not be able to repair it because some tiny part is likely broken, so I should buy a new one on ebay. But I decided to check it out first, so I opened it. This is the top part.

And this is the bottom:

Surprisingly, it was repairable. All I needed to do is just tweak the spring (on the right) to click again.

A few month ago I made a tool for woodburning. I plugged it to 5V computer power supply, it get red-hot and burned in a few seconds. Now I have a regulated power supply, so I can actually use it (after replacing a filament – I took wire from an old hair fan). It works fine from 1V – clearly, 5V was way too much!

Here is a craft I made with it:

And here is the generator. I have a good plan for it!