3-Digit Voltmeter Dongle

This little project shows a USB dongle which houses a inexpensive little 3-digit voltmeter LED module.


On the front, the box has a cutout for a standard 0.36" 3-digit voltmeter module. These modules are easily available and cost less than $US 2 on eBay. The back of the box is equipped with a sliding cover which gives access to the voltmeter, the USB connectors and/or connection cables. The ends of the box contain cutouts for a female and a male USB connector, or alternatively holes for the corresponding cables.


This box can be used as a testing device for monitoring directly the USB voltage. This is useful to monitor the charging voltage of solar powered USB chargers or also to detect voltage drops in the USB 5V line due to overloading of the USB power source. In particular I use this type of voltmeter with my [foldable 5V solar panel](http://www.thingiverse.com/thing:144398) to monitor the output level of the solar cells.


Another use of the