This circuit activates an old cassette recorder when the phone is being used, thus making it possible to record the conversation. The circuit is from a Hands On Electronics from the 90s.
This circuit indicates the logical level of a CMOS circuit, extracting the power from the circuit...
The circuit of the figure serves the same purpose as the previous one (CB5057E), but has a...
The oscillator in figure 1 can be used in alarm, call or warning systems, producing a sound of...