E)
We found this circuit in a PE Hobbyst Handbook from the 90s. The components are common, except the Geiger tube. The transformer is also a component that requires care when choosing.
This circuit is from an American publication from 1970. It uses a coal microphone, which is...
This two-station intercom was found in documentation from 1966. R4 should be experimentally...
Frequency Indicator (CB6342E) This simple circuit was found in an Exar publication from the 1970s....