USB Driver

I got a USB cable fro the dollar store today for, well, one dollar. I was wondering if there was a way I could control the voltage output from my computer. I stripped the cable (it was male to male), and tested the output with my multimeter, too. I am getting about 5vdc, is that normal? I thought I got more out of the USB port. Like I said, I was wondering about any opensource usb control program I could use to control the USB voltage. Is this even possible? Also, I can't program AT ALL, or understand it, either.(if it matters)

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gyromild10 years ago
You can only draw max 5v through USB. Thats the USB standard. As for voltage control, I'm aware there are hardware that can control USB voltages, and sofware+hardware combination that do the same..But it is safe to conclude that it can't be done solely by software. If you want to higher voltage(12V) from your computer, you going to have to draw it from the PSU. Another option, is to draw it from your sound card's speaker out (max 2v). Get different voltage pattern, by playing different tone/audio files. Poke around with you multimeter.
Is the 2v a standard minimum? I've never gotten that much out...
2V is the ceiling value a high-end soundcard can produce, but in most cases the average is around 1V.
. Most (line level?) audio outputs I've seen are rated at 1V P-P. How much they'll actually put out, I dunno. I'm guessing the available current is pretty close to zero.
Hmm... Yeah, the reason I asked, is the most I've ever gotten was 0.2V I don't want it to run anything off it, I just need it to activate a transistor.
> the most I've ever gotten was 0.2V . This may be because you are using a meter calibrated for 50/60Hz to measure an audio freq signal. . And I imagine the RMS value (most meters use a quasi-RMS scale) of an audio signal will be pretty low, compared to the peak value. . Just guessing. Put a 'scope on it to be sure. . > I just need it to activate a transistor . An op-amp should work.
westfw10 years ago
It's firewire that has the higher voltage (12V, IIRC.) In addition to being 5V, USB power is supposed to be limited to 500mA current.
Brennn1010 years ago
"I am getting about 5vdc, is that normal?" Yes, it is normal. 5 Volts is pretty much standard all around.
matseng10 years ago
Sorry, USB is 5 volt only and is not adjustable in any way.