Found in a 1948 MIT documentation, this circuit uses a 0 to 100 uA microammeter as an indicator. The power supply is 150 V.
This circuit uses a digital module from the time. We found it in February 1984 Radio Electronics...
I found this circuit in a Popular Electronics from November 1999. The magazine is no longer...
Found in a 90s 303 Circuits, this circuit has an output power of 100 mW. L1 consists of 890 turns...