This circuit was found in an American publication in 1966. The circuit uses a general-purpose FET that admits an equivalent. The instrument is a 250 uA full-scale microammeter.
We found this circuit on a Radio Electronics. Similar configurations can be found in this section. The...
This circuit was found in the January 1989 issue of Radio Electronics magazine. The circuit sends...
This circuit is from General Electric from the 80s, using a relay with high current contacts (20...