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.
Found in old documentation, this circuit makes use of amplifiers of the time, uncommon today. Next...
Rumble is a low-frequency oscillation that occurs in turntables due to variations in motor speed....
This circuit was found in a Popular Electronics from the 90s. The circuit uses common components...