Plant soil heater (CB7964E)

This circuit was found in a 90’s 303 Circuits. The components are from the period and the heating system depends on the resistive element.

| Clique na imagem para ampliar |

Microphone Amplifier (CB12896E)
This counterphase circuit is from a 1973 publication, and can work with mains voltages or 12 V....
Digital Switch (CB17220E)
This circuit can be used to directly control direct current loads or higher alternating current loads...
AD converter for data acquisition (CB12781E)
The acquisition of data, from a transducer, so that these data can be converted to digital form...