Suggested by a 90’s Radio Electronics, this circuit automatically activates the recording switch of an old tape recorder. It can be adapted for other purposes.
This circuit for common analog telephones was found in March 1982 Radio Electronics magazine. It...
Found in American documentation from the 90s, this CMOS circuit detects the source of a signal and can...
Found in American documentation from the 1980s, this circuit applies to any operational amplifier,...