This circuit was found in the February 1997 Electronics Now magazine. The circuit has a power supply for the NE602 and free inputs and outputs for projects.
This circuit makes use of an operational amplifier from the 80's. The circuit can be implemented with...
When the power is cut off, this circuit keeps the flashlight on for a while, allowing it to be...
Using the CK722 this directional photometer was published in Radio Electronics magazine in July...