Monday, 17 March 2014

USB power monitor

I bought this as my 'frivolous' purchase on ebay. It just sort of took my fancy, and I thought it could be reasonably useful.

Its nothing complex, looking through the translucent blue plastic case, it looks to be a simple VOM/Display Driver chip and a 4x 7-seg LED display block. Im guessing that the current monitoring is done after the supply for the LEDs is taken, as with no USB load it does read 0A.

I think its name of 'Charger Doctor' is supposed to indicate its intended use of checking when a USB port is used for charging a device. I have it now connected charging my Kindle

80-90mA seems to be what the Kindle is taking, and with this load the USB port is running at 5.07v.  I did try earlier with one of the RTL SDR dongles, which took about 110mA, and the voltage dropped to about 4.9v

Yes, fairly frivolous. Yes, reasonably useful occasionally. Worth the £1.99 from the far east, free shipping? Absolutely.

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