This circuit has its application suggested in an alarm system. The circuit is from an old RCA manual. R1 has 5.6 ohm, R2 22k, R3 2k2. The capacitor is 8 uF.
This circuit was found in a 90s Popular Electronics. The sensors can be common speakers that reach...
This variable oscillator with crystal was found in a Popular Electronics of the 90s. The circuit uses...
This sensor circuit was found in an American 1980s documentation. Modern operational amplifiers can...