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CAT # PM-21 (6 Reviews) Write a Review

$ 6.95
$6.95 each
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Product Description
20 volt scale. LCD display size: 1.84" x 0.78". Character height: 0.5". Bezel dimensions: 2.65" x 1.60". Flat-black bezel and body are one unit. Snap-mounts from front into 2.12" x 1.50" chassis cutout. 9 Vdc operation. Auto polarity indication.
WARNING: May cause cancer or reproductive harm.
California Prop. 65
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Customer Reviews (6 Reviews)

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Great Inexpensive meter

Reviewer: from Waukegan, Illinois

I needed to monitor the batteries in the RV, one for the motor battery and one for the coach battery. These were perfect and to keep drain to a minimum, I used a separate 9v battery to power the meters-perfect.
Actually was priceless in finding an electrical problem involving the battery and now to watch charge level when the solar panel is maintaining the battery while the coach sits. Connections are not too bad, I would say almost anyone can do it as long as you are not changing voltage resistors. The only thing that would make the meter better would be back lit displays.... Thumbs up!!

5 of 5 people found this review helpful. Do you? Yes No  Certified buyer

Great for monitoring a 12 volt battery

Reviewer: from Southern California, USA

I purchased this meter to monitor the status of our 12 volt trailer battery/solar charging system. It works fine, although the hundredths digit tends to jump around alot, +/- 0.03volts (the reading is good and steady on my Fluke DVM). It needs a separate 8-12 volt supply for operation and draws 1mA. It's the same meter as PM-200 but with added resistors to convert it to 20 volts. I think it's a good bargain.

4 of 4 people found this review helpful. Do you? Yes No

Good Meter...with a few issues

Reviewer: from Parsippany, NJ

I bought this meter because of it's voltage range, 0-20V. The hundredths of a volt digit jumps around (+/- 0.03V) and adding a cap at the input did not fix the bobble. Also, I had to use the onboard trim pot to get it to read the same as my DMM. The PM-21 was about one volt low compared to the Velleman DVM850. An operating manual and troubleshooting guide would also be useful.

1 of 2 people found this review helpful. Do you? Yes No  Certified buyer

Which meter to select

Reviewer: from New Bern, NC. USA

There are 4 LCD meters offered. three are identical. PM 200, PM 21 and PM 22 are the same meter with different scale resistors and with the decimal point moved.

The model PM 128 has a bezel and two screws such that the chassis or mounting surface is squeezed between the bezel and the meter. This meter has a very similar chip as the others except the divider resistors and decimal pins are set to the most sensitive position. The instructions tell you what resistors to install for the scale you want.

All 4 of the meters use the same divider and decimal point selection method.

When installing the divider resistors be careful not to drop solder or anything else below the circuit card. There are a stack of conductive rubbers connecting the circuit card to the display. I have never been able to get all the diplay segments to operate whenever I have takes the conductive rubbers out. Joel

2 of 2 people found this review helpful. Do you? Yes No

Isolated PS for this meter - DC-32

Reviewer: from Nevada City, CA

See my app note for the DC-32 on creating a power supply for this meter if you are not using a battery.

Meters in this series are stable and good quality display .

2 of 2 people found this review helpful. Do you? Yes No
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