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Posts: 949 | Thanked: 14 times | Joined on Jul 2005
#21
Originally Posted by brothers
Long ago, in a galaxy far, far away...

- Dennis Brothers
Live via 770 tap-tap:

Kneel, you peasants!! We have been visited by an UberUberHackerGeekLeet!! I get first touch of the hem of his garment!
 
Posts: 191 | Thanked: 9 times | Joined on Nov 2005
#22
Originally Posted by fpp
Addendum :Looking to test its accuracy at the various settings, I was shocked to find that no matter what the buttons were supposed to select, it now always unflinching delivered between 18 and 20V...
Now I know why those fixed-track racing cars were hard to control in the bends :-)
Those things are usually quite bad with their voltages at the best of times but yeah, that one sounds buggered!

Also be aware if you're using a digital meter it puts almost no load on the power supply. If you really want to know what the voltage is you need to measure across the supply while it is powering whatever it is.

I was playing with my little powered USB setup yesterday and showing my friends my USB pen drive working. Unfortunately my low voltage warning LED started flashing after only a few minutes. I am sure the drive doesn't use that much power so I am going to try actually measuring the current drains of that and the keyboard I have (which I still can't get to work properly - Grrrrrrr!). I'll wire up a little USB extension lead made from the hacked up Nokia one so I can hook up my meter and measure the current. I will also check the current at the battery if I can. It could be the batteries weren't fully charged. I think the plug on my charger wall wart might be a bit touchy. I need another LED to show when it is charging I guess. Hmmm, actually a dual colour one might be nice.
 
Posts: 209 | Thanked: 8 times | Joined on Nov 2005 @ Fishers, Indiana
#23
For those interested, I've removed the "stock" cable on my USB keyboard and replaced it with a thinner, shorter A->mini B cable that has a home-made "Y" at the end. No adapters needed to work on a PC/hub or direct to the 770. I added a 100 ohm resistor in series with the keyboard power which will prevent potentially large amounts of current from flowing if I inadvertently leave the batteries connected when plugging into a hub or PC (and the batteries are discharged). This way it's impossible for more than 50 mA to flow if there's a dead short at the keyboard end, not that that would ever happen

See here: http://lbattraw.home.insightbb.com/
 
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