I attached split the end of a USB wire and attached a switch. When I press the switch, I measure 5V from the port, but am only measuring 33mA. Why am I getting only 33mA instead of 100mA?
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asked Oct 30, 2010 at 3:14
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1\$\begingroup\$ What is the other end of the USB cable plugged into? \$\endgroup\$– pingsweptCommented Oct 30, 2010 at 6:34
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\$\begingroup\$ It's connected to the multimeter. \$\endgroup\$– 200ok404notfoundCommented Oct 30, 2010 at 16:32
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1 Answer
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There is a decent chance that the computer is detecting a short and limiting the current back.
As pingswept said,
try a 50 ohm resistor
This will stop the computer from thinking there is broken hardware connected.
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4\$\begingroup\$ I think Kortuk is on the right track. Try putting a 5 V / 0.1 A = 50 ohm resistor in series with the switch. \$\endgroup\$ Commented Oct 30, 2010 at 6:36