Found in a 1980s German publication, this circuit tests batteries by type. The circuit is based on a range of LEDs of different colors and is given a table with indications for various voltage ranges.
We found this circuit in an internet documentation. The circuit uses a 1 mA instrument, and the...
This circuit can be used to measure the frequency of a low frequency square signal. The signal can be...
This circuit is from 1985 documentation. The integrated circuit used is not very common today, but...