Logic testers are simple but very helpful devices in testing digital circuits. A logic probe can be designed in many different ways. In this particular design, a combination of discrete and TTL logic ...

This simple logic probe has both LEDs on with no signal at the input but due to the nor gates connected to the probe, indicates correctly when a high or low signal is present. It also works correctly ...

As I mentioned in my recent columns on the topic of adding pull-up or pull-down resistors to the inputs of unused or partially used logic gates and functions (see Part 1, Part 2, and Part 3), I was ...