Tuesday, January 3, 2017

DT9205A - another cheap multimeter

I talked about the Cen-Tech multimeter, which was a little better than expected.  Another cheap multimeter is DT9205A.  There are actually several versions which have slightly different looks.  The one here costs $9 (including shipping); it has no discernible manufacturer brand information and comes with a rather generic users manual, but at least it has accuracy specifications.

The DC voltage accuracy is +/-(0.8% + 3), so measuring 5V, it could be off by as much as 70mV.  It turns out the measurements are much better than specified.  At 1V, the measurement is within 1mV and at 10V, the measurement is within 10mV.  However at 5V, the measurement is off by 30mV.

While the DC voltage measurement seems OK, other measurements do not fare as well.  A 1.6K Ohms resistor should be within +/-(0.8%+2), or +/-15 Ohms; it is actually off by about -30 Ohms, twice the limit; and 31.6KOhms off by -1K Ohms, again twice the spec.

The meter has superficial resemblance to the Fluke multimeter, which costs around $400.  The venerable Fluke 87 has the DC voltage accuracy specification of +/-(0.1% + 1) over all the ranges and the resistance accuracy of +/-(0.2% + 1).  So the accuracy specification is about an order of magnitude better on paper.

The Cen-Tech multimeter actually has much better accuracy for less than half the price.  Although this meter has additional desirable features: the auto power off, continuity beep, capacitance measurement, wider resistance measurement range, 10MOhm input resistance for voltage measurement (for 20V and upper range),  the poor accuracy is enough of a disappointment to not recommend it for purchase.


1 comment:

  1. See http://goughlui.com/2014/11/17/investigation-how-accurate-is-that-3-5-digit-multimeter/ for an excellent report.

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