DVD-RW motor?

All things antweight

Moderators: petec, administrator, BeligerAnt

Post Reply
User avatar
LimaHotel
Posts: 165
Joined: Fri Mar 16, 2018 10:30 am
Location: W. Devon

DVD-RW motor?

Post by LimaHotel » Wed Apr 10, 2019 1:42 pm

So all I know about this is we had an old DVD-rom drive. Old as in PATA old. Anyway, it was kinda dead - so I killed it more.
With reckless abandon, I ripped out all the motors (all 3 of them - the tiny little brushless on the wormgear looked like that was the dead part of the drive as it was a little charred around the edges) and helped myself to whatever metal the casing is made of.
So one of the motors, the disc tray open-close motor, is a bog standard brushed motor that spins away quite happily off a lipo. Not a clue how torquey or fast, but it spins.
The disc-spin motor however is brushless. And has 4 wires. Why the heck does it have 4 wires?
Also all I know about the motor is that I pulled it from a DVD-RW drive. I'm aware I'm never likely to use this (I mean, it's cheap enough to just buy a brushless and know exactly what you're dealing with) but there's just something about salvaged parts...
Anyway. Yeah. Does anyone have a clue what the 4th wire is all about?

Image
Jiggy Sawdust (Grabber)
Jammin' Good with Weird and Flippy (Rear-hinged Flipper)
The Pushbot from Mars (4wd Pushbot)

Key Grip (Retired)

User avatar
MarkR
Posts: 212
Joined: Mon Dec 18, 2017 12:46 pm
Location: Reading Hackspace
Contact:

Re: DVD-RW motor?

Post by MarkR » Wed Apr 10, 2019 1:54 pm

It is probably a brushless motor. I'm fairly sure that the 4th wire is a centre-point wire in the Y configuration of the brushless.

It could be difficult to identify the wires. I suggest something like this:

* Measure the resistance between each pair of wires
* The one with the lower resistance to the others, is the centre wire. It should be approximately half, so if the resistance between U&V, V&W and W&V is 2 ohms, the resistance between any phase and common would be 1 ohm

There are lots of youtube videos of people running these things. There are some cheap speed controller boards you can get for testing purposes, which will run the motor from a DC supply.
Robot: Betsie - RaspberryPi controlled flipper bot with gyro stablisation - too clever for her own good?

Post Reply