Re: Canoscan Lide 210 Scanner
On 10/30/2014 03:16 AM, Johann Spies wrote:
This is not Debian specific, but as I experienced it on Debian and initially thought that it might be a Debian problem, it may help some other users.
I recently bought the scanner specified in the subject line after reading that the saned team claims it has "complete" support. I first tried it out on my Desktop which has something like 8 usb2 ports. I had limited success and was frustrated. Then I took it to work and tested it with my work laptop with 4 usb2 ports and it worked without a problem.
At home I tested it on my other Debian laptop which have two usb3-ports and two usb2 ports. On the USB-3 port I experienced the same problems I had on my Desktop. Moving the connection to a usb2-port everything worked as expected.
My thought on this is that on the Desktop there was not enough power coming through the usb-port and on the usb3-port there the power was too much.
This scanner only works with the electricity it gets through the usb-connection.
Regards
Johann
--
Because experiencing your loyal love is better than life itself,
my lips will praise you. (Psalm 63:3)
As a retired engineer, I can tell you that "the power was too much" is ridiculous. Assuming the voltage is correct--which it ought to be, to keep from
blowing up whatever is plugged into the port, there cannot be "too much" power. Power is determined by voltage and current: voltage (in volts) times
current (in amps) equals power (in watts). The voltage, we have determined here is constant--5VDC. The current is determined by the resistance of the
load--current = voltage divided by resistance (in ohms). Any electrical device has resistance. In this case, it's your scanner. You have no way to measure
that resistance, but it will be determined by the characteristics of the device. For instance, there is probably a passive resistance, when the scanner
is not scanning. Then there will be a dynamic resistance, a value determined by the amount of current the scanning motor requires. (Actually determined
by the number of turns and size of wire in the scanning motor.)
You may be correct, however, in thinking that one computer has too little power. If the load--i.e., the scanner--tries to draw more current than the
power supply can produce, the voltage will drop, and the scanning motor will not run, or the lamp may become too dim, or some combination of things.
--doug
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