Following the American FCC rules, this 90s Radio Electronics circuit shows how to use a transformer to isolate the telephone line from an amplifier circuit.
With this circuit found in a 1965 Electronic Design, it is possible to read a peak voltage of up to...
The circuit below for the LM3900 transconductance amplifier was suggested by National...
This switched stepdown regulator was found in a 60s documentation. It makes use of unusual...