This circuit was obtained in a Hands-On Electronics from the 90's. The circuit turns on one LED at the end of the timer, erasing the other. The timing can be increased by changing C1.
Found in National Semiconductor documentation from the 1980s, this circuit uses an operational...
This basic voltmeter circuit has an input resistance of 2 M. The instrument is 100 uA and the...
This simple alarm using only transistors was found in a 1990 publication. It can be powered by D...