Reverse polarity protection 2 (CB22140E)

This circuit has an improvement over the previous one as it also has an LED indicator for correct polarity.

Voltage Doubler using the 555 - II (CB1234E)
This traditional doubler configuration with the 555 IC can be found in other articles on the...
Neon Head or Tail (CB11603E)
This traditional circuit with a neon lamp is a flip-flop that draws which of the two lamps will...
Indicator for windscreen wiper (CB6038E)
This sophisticated circuit is from old Motorola documentation, using common integrated devices...