Something new for builders: The Universal Motor

[conradelektro]

Such an universal motor could be driven with this http://www.intersil.com/content/dam/Intersil/documents/fn36/fn3659.pdf (HIP4081A,  80V/2.5A Peak, High Frequency Full Bridge FET Driver).

There a similar drivers for higher loads.

For me these brushless outrunners http://www.conrad.at/ce/de/product/231867/Robbe-Roxxy-BL-Outrunner-2824-34-7-12-V-Umin-pro-Volt-1100-Turns are interesting. Of course there are numerous drivers on the market. But coming up with a new (and hopefully more efficient) way of rewinding and driving them could be fun.

One should not dismantle these brushless motors. The description of the one I have got says, that it can never be reassembled by hand (has to be done with some machine or special alignment tool).

Greetings, Conrad

[conradelektro]

A YouTube user called DadHav just published an interesting video about driving brushless motors:

http://www.youtube.com/watch?v=8b4xlCKn3LQ

The demonstrated and fully disclosed circuits are worth studying.

Greetings, Conrad

[MileHigh]

Starting in the late 1970s there was the introduction of "direct drive" turntables.   They were beautiful direct-drive brushless dead-silent servo motors.  The platter was the rotor and there were flat induction coils in the base.  I think the flat coils were laid out like radial wedge segments like when you slice an orange in two.  It's been so many years since I looked at one I can't be sure.  I think there was a magnetic tape head reading a magnetized stripe on the inside of the platter for the servo control.  The magnetized stripe had an AC frequency encoded into it.  There might be a microcontroller or some hard-wired logic to implement the servo control.

That might be a fun thing to hack into and re-purpose as a motor with a drive shaft where you could vary the speed by figuring out how to hack into the servo control system.  If you did it right it should self-correct for the torque to maintain constant speed as you vary the load.  If you could figure out how to amplify its feeble torque then you would have a mean variable-speed servo-controlled machine.

They actually should be quite cheap and relatively easy to find online or at Sally Ann or thrift stores.  It's almost sacrilege when you think you might be able to buy a $350 1981 ultra-high-precision smart high-tech turntable for $20.

[MileHigh]

What I like about the universal motor is that it has brute-force torque when you first apply power.  Thee is no counter-EMF on start-up so the current draw is high and away she goes.  If you make one yourself you would be trying to balance the magnetic field generated in the stator coils with the magnetic filed generated in the rotor coils.  So you are playing with core materials and core size and numbers of turns on both sides of the divide.  A real balancing act.

[ramset]

ConRad
DadHav is a pulseaholic ....
I am quite sure he will be sporting his wares at the TinMans "pulse off".


These boyz Play hard ball .......and they have "mad" building skills!!


should be fun as well as enlightening ...
Plus they have Prizes !![real stuff, not lollipops and such]
thx
Chet