Abstract: An inexpensive, reliable analog ramped-voltage timing device (34, 36, 38, 40, 44) can be used in a laser echo ranging device capable of resolution in the decimeter range by using a very steep ramp (42), and a flash A/D converter (50) to instantaneouly sample the ramped voltage upon receipt of the laser echo.

Abstract: This circuit measures both the resistance and the capacitance of the parallel RC circuit that is the equivalent of any substantially non-inductive two-port device. Thus, the circuit can measure any resistance, capacitance, RC network, or diode, including photovoltaic diodes. The invention uses an operational amplifier, an audio A.C. oscillator and a voltage measuring device such as a digital RMS voltmeter. The resulting apparatus is small, inexpensive, accurate, and easy to operate. The resistance is measured with the audio oscillator set for a low frequency (such as 70 Hz); the capacitance is measured when the audio oscillator is set at a high frequency (such as 20 KHz). The resultant values can either be calculated using simple formulas or can be displayed directly using an analog or digital circuit.