E7277604 6c23 47bf ac65 f58458506baf


Voltage and Power Monitor for littleBits version 2

by alexpikkert

Published on December 17, 2015

Early November SeventhDwarf shared his Littlebits voltage and power monitor with us, built from an existing USB power monitor and fully integrated in the Littlebits system with bitsnaps.
Thanks SeventhDwarf for this exellent idea!
See his original project:

I wanted to make the same power meter but could not purchase the same USB gadget that was used...
So I used another type of meter with a 4 digit 7-segment display, showing the connected voltage and used current with an interval of a few seconds.

Duration: 10 hrs.

How To Make It

STEP 1 : Buy the power meter

Ec1e4b62 78b4 4293 9333 f1802faef41f

I stumbled upon this power meter in a local shop for just 2.95 Euro...

STEP 2 : Remove both USB connections

Bf6686ac 145e 4149 927d e85ef2db25cc

USB connections

B7a8eb85 7f73 4eb8 9a6d a5375fbbc527

Wires connected

Bb7a2536 1e2f 4a2a 924f edbb62676173

Wires connected

Remove both USB connections and replace them by wires, red for VCC and black for GND. he USB connectors have four pins, the outer ones are for the VCC and GND connections, the inner two are for the data connections, they are not used here. Remember which connection is for the incoming power.

More information can be found at:


STEP 3 : The bitsnaps

4afafecc aaae 4942 9656 fc257d6bb42a

Prepare a small PCB with bitsnaps on both sides. This must be done very secure, else the bitsnaps will get loose. I added small interconnection wires to the bitsnap connections to make the soldered part a little longer and thus stronger. The little plastic pins on the bitsnaps needed bigger holes to fit in. I glued the bitsnaps to the PCB and after soldering the connections I melted both plastic pins with my soldering iron to secure the bitsnaps.

STEP 4 : Mounting the meter on the PCB

8ddc8684 b842 4e06 ba90 f432e46a422e

The wiring

139df9f0 190f 4e50 bad6 1f37325ff98a

The finished meter.

I used some small pieces of wood and double sided adhesive tape to fix the meter on the surface of the PCB. Then I connected the red and black wiring, with the incoming power connection on the left bitsnap. Also the middle bitsnap connections (the SIG line) must be connected with each other.

STEP 5 : and see here, the meter is working!

8717b9b1 c121 4159 93ba 051b72398ddf

It works !

STEP 6 : The wiring diagram

494df955 86ca 4ea2 92ab 22ec9af0a5bb

This is the wiring diagram. the meter uses a resistor of 0.05 Ohm in the GND line to convert the flowing current to an internal voltage value that can be measured and shown on the display.

Related Projects

Sense-o-Scope #InventforGood

For many people, especially people on the autism spectrum, bright lights and loud noises can be overwhelming. The Sense-o-Scope li...

Play A Song

Serenade a friend!Learn a song with our color coded sheet music.

Kids Night Out at the Art Explorium (aka Parent's Date Night!)

Pizza + littleBits + Art + Robots = Best Bits Night Ever!! While moms, dads, grandmas & grandpas enjoyed a night on the t...