Sensor for heart monitor (CB21075E)

We found this heart rate sensor circuit in a Popular Electronics from the 90s. The placement of the emitter and the receiver is important.

| Clique na imagem para ampliar |

Relay PNP Driver (CB11196E)
This circuit was obtained in a publication of my own (Newton C. Braga) used to excite relays up to...
Infrared Optical Link (CB14674E)
In the figure we have the transmitter and the receiver for an optical audio link via infrared. The...
Random Neon Flasher (CB13583E)
This circuit causes neon lamps to flash randomly from a low voltage supply (1.5 to 3 V). The...