USB meter: Online Test

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Official specifications:
I found this unit on Ebay at a dealer called sellerbible.



How does it look

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This usb meter has a cable on the usb input.

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A switch is used to select between voltage and current display.

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In addition to the usb output, there is also a DC barrel connector for 5 volt input.
There is no markings on the device showing the DC connector is for 5 volt input.

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There is no screws, I could just pry the bottom off. I was a bit surprised about the inside with two circuit boards and lots of wires.

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Four screws later and the circuit board is out together with the display.

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It looks like this device can be made in two version with different current resolution.
The black blob is the microprocessor, the raw chip is mounted directly on the circuit board.

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The current sense resistor is a piece of wire.

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Two quality trimpots to adjust current and voltage readings.



Measurements

Test




Temp734

M1:36,8C, M2:36,4C, HS1: 42,1C
Notice that the cable is warm, i.e. the resistance in the cable will loose some power.

Temp735

M1: 39,4C, HS1: 43,1C



Conclusion

This usb meter works fairly well, but I would have liked some markings for the DC connector.
A acceptable device for people that want a manual V/A switch.



Notes

How do I make the test