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invention

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:
http://littlebits.cc/projects/voltage-and-power-monitor-for-littlebits

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

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

STEP 2 : Remove both USB connections

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USB connections

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Wires connected

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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:

http://www.electroschematics.com/12052/usb-charger-doctor-unboxed/

STEP 3 : The bitsnaps

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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

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The wiring

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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!

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It works !

STEP 6 : The wiring diagram

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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.

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