Handy, Quick and Easy For DTL, TTL and CMOS High Frequency Response Instant Indication Pulse Memory Function 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 "TTL". 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 detecting and storing pulse or level transition, set lower select switch to side marked "PULSE" first. Contact the probe pin to the point to be tested. The LEDs indicate the basic state. Then set the lower select switch to the side marked without label. The orange LED lights when any pulse or level transition is detected. The pulse direction, in comparison with the original basic state, can be determined. After use, reset logic probe by setting the lower select switch back to side marked "PULSE". Color: Grey Material: Plastic Size: 14 x 3 cm Package Contents: 1 x Logic Probe Note: Light reflection and different displays may cause the color of the item in the picture to be slightly different from the real thing. The measurement allowed error is +/- 1-3 cm.