Logic Probe Circuit Diagram. Components needed 4011 nand gate chip green led red led 2 470ω resistors power source the pinout of the 4011 is shown below so that you can see how to connect it in the circuit. Here is the schematic diagram of the circuit.
Logic testers are simple but very helpful devices in testing digital circuits. Thanks to the white leds you will always have a light work illuminating the wires under test. The circuit of the logic probe and its lm339 quad comparator core.
The use of a lm393 for the comparator in the circuit plus 555 are the ics.
When the high condition is probed q2 and q1 transistor will be activated shorting r2 and led1 to. Here is the schematic diagram of the circuit. Thanks to the white leds you will always have a light work illuminating the wires under test. The use of a lm393 for the comparator in the circuit plus 555 are the ics.