Here is a useful circuit for Arduino lovers and experimenters. It is a simple digital voltmeter, which can safely measure input dc voltages in 0 to 30V range. The Arduino board can be powered from a ...

If you’re reading Hackaday, you almost certainly have a voltmeter. Matter of fact, we wouldn’t be surprised to hear you had two of them. But what if you needed to monitor four voltage levels at once?

We all like cheap items off eBay especially if they do cool and unusual things, sometimes we get so carried away by the price that we do not even realize that fact that we do not know anything about ...