This circuit is from the 1993 Motorola Linear Interface ICs. The circuit must use symmetrical power supply and equivalent operational can be used.
Old multimeters used a 22.5 V battery for high resistance measurements. If you have one, you...
This circuit has an opposite action to the previous one, triggering when light falls on the...
This circuit was found in a Popular Electronics from 1991. The transistor could be the BC548. The...