This circuit is used to detect PLL signals from the 4046 IC. The circuit is from an Electronics Now from October 1994. The indication is made through LEDs.
This configuration from the 1970s can be applied to modern equivalent operational amplifiers. The...
This simple alarm using only transistors was found in a 1990 publication. It can be powered by D...
The circuit presented was found in the 1994 National Instruments Linear Applications Handbook and...