High current DC motor RPM controller circuit

[THEONE]

I would like to built a circuit as the tittle says. The motor is going to be a windshield wipers car motor driving from a pc power supply at 12v. It going to be used as a homemade ball mill motor and is going to operate more than 4 days continiously. Any thoughts ? Edited January 26, 2019 by THEONE

[Arthur]

First thoughts would be to get a motor of a reasonable RPM and then use pulleys and belts to drive a suitable drum.

Second thoughts would include a length of iron wire in the motor supply just to reduce the current.

 

When driving motors the electronics need to be carefully made to accept the nasty inductive spikes that will occur at switch on and switch off.

[Fulmen]

Don't. Building such a circuit is a demanding challenge, if you have to ask you probably won't have the skills for it. An AC motor geared down to the proper speed will be the most reliable solution IMHO.

[TheArchitect23]

A windshield wiper motor is a poor choice as they are designed to be run with air and water flow for cooling. It will fail amazingly fast. The computer power supply can easily power the motor on its own. BUT A good 90V dc motor with rectifier and PWM controller like a MC80 or KB electronics would run quieter and less hot continuously.

[THEONE]

TheArchitect all those motors i have seen so far they do not have any cooling system. Also i was intended to add some fans and heat sinks in order to operate 24h/day.

 

I also found this simple circuit that i believe it is going to be ok for my purpose.

 

 

https://www.electronicshub.org/wp-content/uploads/2015/08/Speed-Control-of-DC-Motor-Circuit-Diagram.jpg

Edited January 26, 2019 by THEONE

[PTFE]

its probably not so hard and ive done it before.

i will give you a shematic soon

[patsroom]

I am just wondering, are you going to be feeding the stock chemicals for the star into the star roller for 24 hours a day? And how big are you going to make the stars? Like I said earlier I was just "wondering".....................Pat

[THEONE]

It is going to be a ball mill for BP and maybe AL

[MadMat]

TheArchitect all those motors i have seen so far they do not have any cooling system. Also i was intended to add some fans and heat sinks in order to operate 24h/day.

 

I also found this simple circuit that i believe it is going to be ok for my purpose.

 

 

https://www.electronicshub.org/wp-content/uploads/2015/08/Speed-Control-of-DC-Motor-Circuit-Diagram.jp

Make sure you have that FET on a good sized heatsink

[Arthur]

As you turn down the power input you reduce the available power output -til the motor just stalls! Put the FET on a big heatsink and make sure that the snubber is more than just a 1n4007 -possibly several in parallel and maybe a 0.01uF in series with a 100ohm resistor. Every pulse from the 555 will make a nice fat killer pulse across the motor coil.

[PTFE]

With this shematic you should have a nice pwm and frequency controller.

Unfortunately i just moved, so i have no workshop to test it, but i've built it several times before to drive high voltage high frequency half-bridge-drivers and im sure it should work. i used it once to drive a motor too. (its now 2 years sice ive built my last electronics stuff)

Here is a page i love to refer to when working with the tl494.

http://www.ti.com/lit/an/slva001e/slva001e.pdf

 

You should use a powerfull pwrsply for the tl494+driver.

With C4 you can set the frequency range. You may change it to 4.7uf or smaller. I also tried different values to test how my motor reacts to different frequencies.

R1 is used to vary the frequency R2 to vary the Puls-widh.

 

The FET should be mounted on a good heatsink. The input voltage of the Motor should be kepth in the range of 1/4-1/3 Vds of the FET to keep transient voltages in a save range.(Irfp 250; Vds:200V so the max. Input should not exceed 50-65V)

 

The noted currents are made with some reserve. also with the 90n20d you CAN switch 94A without killing the FET, but i don't think the leads will hold up.

 

And please be careful. Don't use the mains without transformer and especially for the Motor circuit keep you save.

 

If you plan to built it, Don't be shy and buy several tl494's/7667/ZD15/FET's/Uf5408 as these can die if something goes wrong.

 

PTFE

 

 

 

[PTFE]

edit*
Im really not sure about the timing cap. You may take a look into the datasheet of the 494. It took me an hour for the circuit and now im tired.

I would try a 0.47uF film-capacitor first.

[THEONE]

Ok PTFE i will try it. Thanks a lot for your info

[PTFE]

Here is another nice shematic with the tl494 with description and video.

[CathieDas]

Hi...what RPM switching rate are you using?Normally not a problem for motor control, the FET is voltage operated, unlike Bipolar which is a current operated device.
Essentially a transconductance device.

[PTFE]

Hi...what RPM switching rate are you using?Normally not a problem for motor control, the FET is voltage operated, unlike Bipolar which is a current operated device.

Essentially a transconductance device.

I played around with the tl494 driver and im not sure which switching frequenzy i used. but I think it was around 26kHz since i dont like a high pitched noise while operating.

[SeaMonkey]

The Pulse Width Modulation Speed Controllers are very effective.

A 12 Volt DC motor can be driven at a low Duty Cycle (Narrow Pulses)

at a suitable frequency to attain slow speed rotation with excellent

torque characteristics. In fact, that is the real advantage of Pulse

Width Speed Controllers. Slow RPMs are quite strong.

 

As pointed out above, when Pulse Driven a DC motor should

have a suitable Diode across its power terminals to shunt the

Inductive Kickback Pulse. This will improve operation and

torque of the motor at slow speeds as well as its efficiency.

[TorrinFu]

Hi...i would like to know what RPM switching rate are you using?Normally not a problem for motor control, the FET is voltage operated, unlike Bipolar which is a current operated device.Essentially a transconductance device.

[Dylman]

Why do u need to run the motor for 4 days straight continuously what do u plan on milling metals?

[SandersReview]

Hi,

1st thoughts you would be to get a motor of a reasonable RPM.

Edited August 6, 2020 by SandersReview

[Piccaso]

Windshield wiper motors are very slow. I would not use one for that. This is what I use on my mill. It is a modified Rebel 17 mill.

https://smile.amazon.com/HVAC-Motor-3000-rpm-115V/dp/B07GZLBQQC/ref=sr_1_99?dchild=1&keywords=dayton+electric+motor+3000+rpm&qid=1598678497&sr=8-99

Here is another good one just not so much power but it is cheaper.

https://www.ebay.com/itm/Dayton-Universal-AC-DC-Open-Motor-1-15-hp-5000-RPM-115V-Rotation-CCW-Model-2M033/401566575741?epid=1000280036&hash=item5d7f3bac7d:g:TkkAAOSweW5VR2Y6

Another

https://www.ebay.com/itm/DAYTON-71903592M-HVAC-Motor-1-10-HP-1550-rpm-115V-3-3/333270050632?_trkparms=aid%3D1110006%26algo%3DHOMESPLICE.SIM%26ao%3D1%26asc%3D20200520130048%26meid%3D7771cea8717a47daa2d9fe79ec81dce2%26pid%3D100005%26rk%3D5%26rkt%3D12%26mehot%3Dsb%26sd%3D401566575741%26itm%3D333270050632%26pmt%3D1%26noa%3D0%26pg%3D2047675%26algv%3DSimplAMLv5PairwiseWebWithBBEV2bDemotion%26brand%3DDayton&_trksid=p2047675.c100005.m1851

Edited August 29, 2020 by Piccaso