Roman numeral display (CB22160E)

This circuit shows numbers I II and III when mounted on its side, depending on the position of the selector switch.

CMOS Alarm (CB4803E)
This circuit is from Popular Electronics of the 90's. It makes use of NO and NC sensors. The relay...
Modulator for rectangular signals (CB21630E)
Based on TTL logic this circuit can vary both the frequency and the pulse width of a rectangular signal....
Interval for windshield wiper (CB22145E)
This circuit was found in an old English publication. The circuit makes use of general-purpose transistors....