Double door bell (CB7559E)

Found in an Elektor from the 90's, this double door-bell drive circuit switches a relay by triggering different points.

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Hand Dryer (CB18786E)
With this circuit it is possible to use a common hair dryer as a hand dryer. The circuit is timed...
8 Channel Encoder with 4017 (CB4530E)
This circuit was obtained from an English magazine from 1979, but can be easily assembled today...
Continuity Tester (CB10617E)
This circuit was obtained in a 1975 magazine, but it can be easily assembled using BC548...