Digital logic: the heart of today's technological revolution. Yet, digital signals are either "on" or "off", and you need an easy way to monitor them. Enter the EBLOG-300, a simple piece of test equipment that comes in very handy. Logic probes test digital circuits at various points, and show whether that point is high, low, or constantly changing. They help you understand and troubleshoot logic gates, timers, clocks, counters, prescalers, and other digital circuits you might come across. The logic probe is powered by the circuit under test. Size 4" x 0.75".