Delayed Alarm (CB6418E)

This alarm circuit has a trigger delay system. The circuit was found in a Popular Electronics of the 90s. The components are common.

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Telephone switchboard (CB25400E)
This circuit monitors an old-style analog telephone line. We found it in the September 1991 issue...
Center Tap Simulation with Diodes (CB4140E)
In the figure we show how two diodes can be used to simulate the center tap of a push-pull driver step....
LED Bargraph (CB6219E)
This circuit was found in a General Electric / RCA documentation from the 1980s. The circuit is...