Jump to content


Photo
- - - - -

High current DC motor RPM controller circuit


  • Please log in to reply
13 replies to this topic

#1 THEONE

THEONE

    Pyrotechnician

  • Full Member
  • PipPipPipPip
  • 436 posts

Posted 26 January 2019 - 03:43 AM

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 by THEONE, 26 January 2019 - 03:44 AM.


#2 Arthur

Arthur

    Firebreather

  • HE Qualified
  • PipPipPipPipPip
  • 2,974 posts

Posted 26 January 2019 - 04:13 AM

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. 


  • MBaggs likes this

#3 Fulmen

Fulmen

    Pyromaniac

  • HE Qualified
  • PipPipPip
  • 153 posts
  • Gender:Male

Posted 26 January 2019 - 06:55 AM

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.



#4 TheArchitect23

TheArchitect23

    Pyromaniac

  • Donator - HE
  • PipPipPip
  • 182 posts
  • Gender:Male
  • Location:Up In The Sky
  • Interests:Engineering

Posted 26 January 2019 - 12:18 PM

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. 



#5 THEONE

THEONE

    Pyrotechnician

  • Full Member
  • PipPipPipPip
  • 436 posts

Posted 26 January 2019 - 01:22 PM

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.electron...uit-Diagram.jpg

Edited by THEONE, 26 January 2019 - 01:32 PM.


#6 PTFE

PTFE

    Pyromaniac

  • Full Member
  • PipPipPip
  • 52 posts
  • Gender:Male
  • Interests:Elektrochemistry, high voltage stuff

Posted 26 January 2019 - 03:48 PM

its probably not so hard and ive done it before.

 i will give you a shematic soon



#7 patsroom

patsroom

    Pyrotechnician

  • Donator - HE
  • PipPipPipPip
  • 338 posts
  • Gender:Male

Posted 26 January 2019 - 10:55 PM

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



#8 THEONE

THEONE

    Pyrotechnician

  • Full Member
  • PipPipPipPip
  • 436 posts

Posted 27 January 2019 - 04:02 AM

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

#9 MadMat

MadMat

    Pyrotechnician

  • Donator - HE
  • PipPipPipPip
  • 643 posts
  • Gender:Male
  • Location:North-east MO
  • Interests:Anything scientific.

Posted 27 January 2019 - 12:33 PM

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.electron...cuit-Diagram.jp

Make sure you have that FET on a good sized heatsink



#10 Arthur

Arthur

    Firebreather

  • HE Qualified
  • PipPipPipPipPip
  • 2,974 posts

Posted 27 January 2019 - 12:49 PM

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.



#11 PTFE

PTFE

    Pyromaniac

  • Full Member
  • PipPipPip
  • 52 posts
  • Gender:Male
  • Interests:Elektrochemistry, high voltage stuff

Posted 27 January 2019 - 02:59 PM

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/li...1e/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 :)

 

 

 

Attached Files



#12 PTFE

PTFE

    Pyromaniac

  • Full Member
  • PipPipPip
  • 52 posts
  • Gender:Male
  • Interests:Elektrochemistry, high voltage stuff

Posted 27 January 2019 - 03:40 PM

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.



#13 THEONE

THEONE

    Pyrotechnician

  • Full Member
  • PipPipPipPip
  • 436 posts

Posted 27 January 2019 - 04:03 PM

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

#14 PTFE

PTFE

    Pyromaniac

  • Full Member
  • PipPipPip
  • 52 posts
  • Gender:Male
  • Interests:Elektrochemistry, high voltage stuff

Posted 08 February 2019 - 08:29 AM



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






0 user(s) are reading this topic

0 members, 0 guests, 0 anonymous users