Photometer for enlarger (CB8342E)

This circuit for old photo enlargers was found in a 1970s RCA manual. The components are from the time, but modern equivalents can be used.

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Operational Oscillator (CB5915E)
We have in the figure a traditional amplifier configuration with operational amplifier. The source...
10 s to 10 m sequential timer (CB1519E )
This circuit was found in a 1977 Radio Shack documentation. The circuit is TTL, which must be...
Modulator with TAA111 (CB19432E)
This circuit is suitable for modulating small FM transmitters for eavesdropping or espionage. The...