17MHz Logic Probe with Audible ToneFeatures Maximum input frequency: 17MHz; Minimum pulse width: 30ns; Pulse flash time: 500ms; Audible tones for high and low; Input impedance: 1M; Power supply protection: A 20V; TTL threshold: Low=0.8V A 0.2V, High=2.3V A 0.2V; CMOS threshold: Low=30% Vcc, High=70% Vcc ; pagebreak Overview This 17 MHz logic probe requires no batteries and produces an audible tone.