USB current detection

[EventHorizon]

Hello all! I'm working on an introductory level engineering project which revolves around geothermal energy production. Essentially our design is going to take pressurized steam and pass it through a "turbine" to generate electricity. I have salvaged 2 fans connected to a usb cable from an old laptop cooling fans to use as the turbine system. I know that in the same way power can be applied to a motor to make it run, a motor forced to run physically will produce some current. My question is whether this current can be detected by using a multimeter on some pins in the USB connector which the fans are already attached to. I know that pin #1 in the plug is the VCC +5 V pin, however how can I use this to detect a current, if at all? Would it make more sense to just remove the plug entirely and detect current via the wiring instead? Any help would be greatly appreciated!

 

[Resqueline]

If there's nothing else connected (to that USB) they can put out a few volts. If you spin them fast enough I'm sure they can light a LED.
12V fans won't need as much speed to produce the same voltage as 5V fans does.

 

[TedA]

EventHorizon,

You need to try your fan, and see what it does. Many "computer fans" use brushless motors, and have no mechanical commutator.
The brushless motors have an electronic circuit to switch the DC power to the motor windings. Those fans are unlikely to work for you.
You may need to find a battery powered fan at the cheap shop. I suppose even some of those may have brushless motors, but I expect that most have motors with mechanical commutators, that will serve as generators.

Ted

 

[cjdelphi]

Computer fans are brushless, meaning if you spin it no voltage will come out, you need a different fan not from a computer then it will work

 

[Resqueline]

On the contrary dear members, brusless fans does rectify some of the voltage induced by its magnets. Of course I even tested it before posting my statement.

 

[nowire9]

The easiest way to detect current would be to get an ammeter in line with the circuit, which would mean using the actual wires instead of the USB connector. Personally, I'd get rid of the USB connector and deal with the wires.

Sounds like a cool project - gives hands-on feedback to textbook teaching.