Simple Cmos Universal Logic Probe Circuit Diagram. Only the CD4009AE hex buffer, two resistors, and two LEDs are required for a logic probe. CMOS logic probe features 10120 input impedance and covers 3 to 15 V range. While LEDs are visible at all voltages, a 1-K!l pot in place of R2 will allow the user to increase brightness at lower voltages.
Simple Cmos Universal Logic Probe Circuit Diagram
