This circuit was found in the September 1992 issue of Radio Electronics magazine. The circuit does not use a transistor to drive the relay and has no adjustments.
This simple window comparator based on the well-known LM339 was found in the June 1998 issue of...
This circuit makes use of a transconductance operational amplifier. It generates signals with TTL...
This circuit has a traditional configuration often found on this site. The transistor must be...