Up to 3 minutes timer (CB21429E)

We found this circuit in a 1967 General Electric SCR manual. The time is set to R1 and depends on C1 which must be a low-leak capacitor.

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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...