This circuit was published in an article in Radio Electronics magazine in October 1988. It uses components that are still common today, except for the sensor, which is a special type from that time.
This circuit was taken from an article in Electronics Now magazine in February 1995. The power...
Found in a Hands On Electronics from the 80's, this circuit activates a relay with alternating...
This circuit was found in a publication of the year 1968. It uses complementary transistor to...