This circuit was found in a 90s Popular Electronics. The sensors can be common speakers that reach from 15k to 25 kHz, such as piezoelectric tweeters.
This sensitive circuit was found in an Electronics Hobbyists Handbook from the 1990s. The circuit can...
This circuit suggested by Motorola can be used as LED high frequency modulator. One possible...
This circuit was obtained in an old American manual. The circuit is valid for any operational. The...