This circuit was found in an article in Electronics Now magazine from March 1997. The transistors are general purpose, and the indicator is a 1 mA full scale analog type.
Using power transistors of the time, this source was published in Radio Electronics magazine in...
Found in an American publication on transistors from the 60's, this circuit uses a transistor...
This circuit is from a very old publication, from the 60s. It uses germanium transistors from the...