This is a circuit suggested by Linear Technology in a 1980s documentation. The integrated circuit is from the era. Observe the input and output voltage.
This simple indicator is for 12 batteries, just adjust the trigger point in the trimpot. The...
This circuit was found in an American 1980s documentation. The circuit can be digitally programmed...
This small tone generator was found in the November 1987 issue of Radio Electronics magazine. The...