Hello, being attracted by old lab instrumentation ( the more switch, led, displays and knobs, the better ) I purchased for approx 20$ a level generator ( W & G PS something ) from a surplus store. The equipment is without user manual. Fact is, I don't have any idea about what I bought ! I tried to use search internet in order to find some info but with poor results. Can someone explain in very simple terms what this ( heavy ) equipment does ? What are the typical applications ? How can I test it ? Where can I find some more info ? Thanks in advance for the help.