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.
This circuit determines the frequency of a signal by beating with a known signal. The circuit was...
With the values of the components indicated, this timer controls intervals from a few seconds to a...
The purpose of this circuit is to automatically turn a water pump on and off. Sensor 1 is the...