Direct Reading Capacitance Meter.
DEPARTMENT OF THE NAVY WASHINGTON DC
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This invention relates to an apparatus for measuring capacitance, especially large capacitance. The resulting measurement is displayed on a meter calibrated in capacitance. One method of determining the capacitance of a large, unknown capacitor is to charge it to a predetermined DC voltage, then discharge it through a known resistor and an SCR while observing the discharge wave form on an oscilloscope. Another method is to insert the unknown capacitor in a bridge circuit in which fixed capacitors and, in some cases, other circuit elements are provided. The present invention obviates the above mentioned prior art by providing a direct reading capacitance meter for measuring a wide range of capacitances. The invention has circuits for a voltage comparator and logic trigger, a flip-flop multi-vibrator, and a ramp generator. The output voltage of the ramp generator is determined by the duration interval of the input pulse, and produces a reading on a meter which is calibrated in three ranges of capacitance to provide the user with a direct reading capacitance meter.
- Test Facilities, Equipment and Methods