3.6 volt motor usb

[Cannibal23]

hey there. need some help on this one. i have a motor that runs using 3.6 volts DC. if i plug that into 5 volts dc will it fry? i would like to hook this up to usb but it only outputs 5v. alternitively there is a 3.3 volt line from the power supply. would it work if i spliced into that to get my voltage ?

[billygoat333]

how many amps does the dc motor take?

[xmastree]

Connecting a couple of rectifier diodes (1N4001 would be an ideal one to use) in series with the motor will drop the 5V down to about 3.8. That should be near enough, although you will only be able to get 500mA, so billygoat's question is important.

The 3.3V line would also work, but there's an awful lot of current available there. Could be fireworks if things go wrong. :dead:

[Cannibal23]

hey there. its a very small device. i have looked all over but i dont see a voltage rating or a rating for milliamps on it at all unfortunately. if i give something not enough miliamps will the device just not turn on or will it get damaged ?

[xmastree]

If it needs higher current than your supply can provide, it won't get damaged but the supply will be dragged down to a lower voltage. This shouldn't affect the supply if it's well protected.
Are you sure it's 3.6V? Where did it come from?

[Cannibal23]

well i know the battery pack measured out to 3.6 volts on the multi meter so im assuming thats the correct input voltage as there isnt really any other major electronics between the battery contacts and the motor itself. not really sure what it was from. found it in my pile of spare electronics parts with 3 button cell batterys taped to it and figured i would see if i could make it run from my computer some how.

[xmastree]

If it runs off three button cells, then a USB port will have enough power to drive it.

If you can find a couple of suitable diodes in that stack of electronic parts, they should be ok to drop the voltage. Each one will drop it by 0.6V so two in series will drop 1.2V, leaving 3.8V for the motor.

They look like this:
http://img.alibaba.com/photo/10823267/1N4001_1N4004_1N4007_Diode.jpg

[Cannibal23]

thanks for your help guys! 1 more quick question. if i hooked up a potentiometer to this thing could i in theory speed up and slow down the motor like a fan controler does or is a diffrent device used for that?

[xmastree]

It would, but you'd need to get the right value. Get it running and measure the current first to see what kind of resistance you need to introduce.

[Cannibal23]

tried the motor on 3.3 volts as i dont have any of those diodes available to me at the moment. i also tried it hooked up to the batteries. the motor worked on both. although it seemed to run alot faster when i had it connected to the 3.3 volt line on a computer power supply then when i had 3 1.3 volt button cells connected. is this from the diffrence in current from my power supply and whats available from the batteries ? i even ran it off of one battery at 1.3 volts and it still turned on but alot slower rpm.

[xmastree]

is this from the diffrence in current from my power supply and whats available from the batteries ?
Yes. the PSU can provide a lot more current than three button cells.
Since you have a meter, try measuring the voltage while the motor is running off the batteries. I suspect it will be lower than 3.6V.
Then connect it to the PSU and measure the current it draws(I assume you know how to go about this.) This will give you an idea about what to use as a speed controller if you want to go down that route.

[crenn]

What is the resistance for the armature winding?

[Cannibal23]

Cren i havent the foggiest idea. wish i did.


Xmas thats kind of what i figured. i will try to find a way to measure the voltage when running from battery. im not familier with how to measure the current though. i imagine there is a setting on my meter to find taht out. is it done diffrently then measuring the voltage?

[xmastree]

Here ya go:

http://www.electronics-radio.com/articles/test-methods/meters/how-to-measure-current.php

DO NOT set the meter on current then connect it across the supply, particularly the PSU. It will go bang. :dead:

[Cannibal23]

got this device all hooked up with 2 of those diodes on the positive lead. took a busted usb mouse cracked it open and stole the cable. as a point of interest the voltage pins on a usb connector are the 2 outer most pins. hooked this all up and it works like a charm. was in too much of a rush to see if it would work to measure out the current. will have to do that later when i choose to put a control nob or other such electronics on here with it. the only thing that concerns me a little is that the motor does get warm. its not untouchably hot or anything but i dont really want to burn it out. is that the current or the voltage? if its the voltage i guess i could get another of those diodes and hook it up with the rest.

[xmastree]

the only thing that concerns me a little is that the motor does get warm. its not untouchably hot or anything but i dont really want to burn it out. is that the current or the voltage?
It's both. The power consumed is given out as heat, and power in Watts is Voltage x Current.
Don't worry about it, it's supposed to get slightly warm.