This 7-tube circuit was obtained from an American publication in 1947. The circuit has a push-pull output with a source using a transformer.
This circuit reinforces signals in a frequency range between 1500 and 2000 Hz for use in...
When a small air current reaches the piezoelectric sensor, a small audio signal is generated and...
This circuit is from a Poptronics, American magazine from August 2000. The circuit can be...