Capacitance Meter
Approx construction cost US$68
Allows any capacitor type to have its true value readily measured.
While it has been possible during most of the "electronics age" to measure both potential difference and current flow with good accuracy and from small values to the very large, measurement of capacitance has always presented problems. Although some modern multimeters do have capacitance-measuring capability, this is often limited to a maximum of around 10 microfarads and is often highly inaccurate at both ends of the scale.
However, the simple circuit described here allows all types of capacitor, including non-polarized, electrolytic and tantalum to be measured accurately and over a wide range. It measures capacitance from a few picofarads to 10,000 microfarads in three sub-scales (10nF, 10F, and 10,000F) and is accurate across the whole range.
It automatically measures high value capacitors at the low frequencies they are likely to encounter when used as reservoirs for d.c. smoothing. Also, the method for accurately measuring small capacitors is only modified, but not limited, by the stray capacitance of the meter itself.
More details on this construction project can be found in the November 2001 issue of EPE Online, the world's first web-delivered electronics and computing hobbyist magazine.
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