In this circuit the LED lights up when the voltage drops below the value set in the trimpot. The transistors can be the BC548. The circuit is from a 1999 American publication.
This circuit was obtained in an old Argentine publication, using germanium transistors and...
This very low resistance meter was found in the February 1995 issue of Electronics Now magazine. The...
Using a CA3130 operational amplifier, this circuit was found in an English publication from 1977....