Infrared detector (CB7814E)

This circuit was found in a Popular Electronics of the 90s. The operational amplifier admits equivalent and the phototransistor can be of any type.

| Clique na imagem para ampliar |

Variable Frequency Oscillator (CB22465E)
This VFO circuit generates signals from 2 Hz to 50 Hz. We found it in Popular Electronics from...
Stereo preamplifier TDA3410 (CB21937E)
Taken from the 1982 SGS manual on integrated circuits, this preamplifier was used in commercial...
Special Sound Generator (CB4454E)
This is an interesting sound effects circuit that uses only discrete components. Components are common...