How to use: 1. Connect RED clip to + terminal and BLACK clip to - terminal of the power source of the circuit under test. The supply voltage should not exceed 18V DC 2. For TTL and DTL, set the upper select switch to the side marked "TIL" For CMOS, set the upper select switch to the side marked "CMOS", contact the probe pin to the point to be tested. The LEDs indicate its logic states: A. ALL LEDs OFF -High impedance B. RED LED ON - High State (1) C. Green LED ON - low State (0) D. Orange LED ON - Pulse 3. For deteching and storing pulse or level transition, set lower select switch to side marked "PULSE" first. Contact the probe pin to the poin to be tested. The LEDs indicate is basic state. Then set the lower select switch to side marked "", The orange LED light when any pulse or level transition is detected. The pulse direction, in comparison with the original basic, state, cabe determined. After use, reset logic probe by setting the lower select switch back to side marked "PULSE"