60 seconds delay lock (CB7231E)

This General Electric circuit triggers on after 60 seconds. The circuit is from 1967 but can be implemented with current components.

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Full wave slave control (CB8156E)
Using SCRs, this circuit from a 1967 General Electric manual allows full wave load control with SCRs....
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This interesting circuit from a publication from the 1970s, measures the intensity of the sound...
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