This circuit was found in a 1924 Gernsback publication. The variable capacitors are dual. Listening is through a high-impedance phone.
This circuit monitors the current in the negative line. The circuit is from a 2005 Linear...
An oscillator whose frequency can be adjusted between 500 Hz and 5 kHz with the use of a...
This circuit allows coupling optical signals to a TTL input with excellent performance. Among the...