Using a 4046 PLL this circuit generates rectangular signals in three wavebands that depend on the capacitors used. The circuit is from a Radio Electronics from December 1989.
This circuit indicates when a 28 V lamp burns, lighting a neon lamp with higher voltage. The...
This circuit, which can be used on an optical link, is suggested by the Texas Instruments...
We found this circuit in a 1992 Popular Electronics. The circuit has an optical sensor with LED...