This circuit was found in a 1967 Electronics World. Transistor Q1 can be a TIP321 and Q2 can be a BC558. The indicator lamp is optional.
This circuit was obtained from a Linear Technology manual from the 1990s. The sensor is of the...
This circuit is from a PE Hobbyst Handbook from 1991. The integrated circuit is a common 555 and...
This traditional circuit with a neon lamp is a flip-flop that draws which of the two lamps will...