Amprobe LP10B Logic-Probes - Manual (Page 12)

8
Specifications
Input signal Levels LED’s BEEPER(LP25B)
Logic “1” TTL: > 2.3 V ± 0.2 VDC HI (Red) ON Fixed Tone
CMOS: >70 % Vcc ± 10% HI (Red) ON
Logic “0” TTL: < 0.8 V ± 0.2 VDC LO (Green) ON Fixed Tone
CMOS: <30 % Vcc ± 10% LO (Green) ON
Bad Logic Level or Open circuit none No Tone