This circuit was found in an article about the 555 in the November 1992 Radio Electronics magazine. The circuit uses a 12 V relay and has two timing ranges.
This filter was obtained from a Linear Technology manual from the 1990s. The power supply must be...
Found in a 90s Popular Electronics, this circuit is intended for amplifying analog video signals....
Based on a 555, this 80's American documentation circuit detects the voltage of a battery and can then...