Alternate use for cheap USB current meter

February 17, 2017


I recently purchased a cheap usb current meter off ebay for a couple dollars from china to measure the quality of all my phone chargers I had sitting around my house. After I got it, I noticed it had a 3 to 30 voltage range so I thought of a way I could repurpose it.


 I have a small homemade power supply I made a while back that I've been using that has to current or voltage indicator. I've just been using a multi-meter which meant I was always having to break the circuit if I wanted to measure the current. Not to mention I'd have to change the settings on the multi-meter and the way the probes are connected. 


What I ended up doing was I made a small female usb breakout board(shown above) to connect to the input of the current meter. I then made a usb cable with flying leads for the V+ and ground to connect to power the circuit I am working on. I did a test using a 100 ohm resistor, and you can see below it reads 100 mA when I have 10 volts across it.  The neat thing is this meter even calculates the resistance and displays that as well. I found however though , for any current readings below 100mA it is less accurate.  It can be off as much as 10 or 20 mA. For its intended use though I think its ok.



The other thing I noticed was this meter also measures the D+ and D- voltage lines. I ended up  hooking up a potentiometer to send 1VDC to the D+ line.  Unfortunately the meter can only measure up to 3 volts on these lines. This could be useful for times where I want to monitor a low voltage, like a comparator reference or something.



Maybe in the future I will buy anther one of these and completely rebuild the enclosure for my power supply so I could monitor both the positive and negative voltage of my supply.



Please reload

Featured Posts

Eagle 8.6 First Impressions

February 7, 2018

Please reload

Recent Posts

November 28, 2019

November 28, 2017

November 2, 2017

October 16, 2017

Please reload

Search By Tags
Please reload

  • Facebook Classic
  • Twitter Classic
  • Google Classic
Follow Us
This site was designed with the
website builder. Create your website today.
Start Now