This 80's circuit has been winning. It is a 1 000 gain sample and hold circuit and an offset current setting. The configuration can be adapted to operate with modern equivalent components.
Oscillators up to some megaherts can be made with comparators like the LM139, 239 or 339. Theses...
I found this circuit in an Electronics Handbook, an American publication from 1989 and that no...
With this circuit it is possible to measure the power of amateur radio transmitters up to about 30...