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 1987 magazine. It measures monitors the heartbeat through a...
This crystal-controlled circuit was obtained from a 1980s documentation. The power supply should be 5...
This circuit is from 1957 Raytheon documentation. The phone must be high impedance with 600 ohms...