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DC Motor control
DocZ
So the plan is to use a 12V wiper motor with a model train DC power pack. I found one but it?s over kill 20V 10amp and a lot of controls to speed up, slow down, breaking and?. I know I will need something in the 12V/5amp range but as I look at other controllers they throw me a curve ball. They start using VA instead of AMPS. So the question is how much VA will I need?
Bob
 
Koffee Kosmo

Quote

DocZ wrote:
So the plan is to use a 12V wiper motor with a model train DC power pack. I found one but it?s over kill 20V 10amp and a lot of controls to speed up, slow down, breaking and?. I know I will need something in the 12V/5amp range but as I look at other controllers they throw me a curve ball. They start using VA instead of AMPS. So the question is how much VA will I need?
Bob


I find that most computer lap top power supplies are made for the job, so if you have one of these lying around I would use one on them

But to get your head around VA or Amps
Try this converter
http://bugclub.or...scalc.html

KK
I home roast and I like it. Designer of the KKTO
Roaster Build information
https://forum.hom...ad_id=1142

https://docs.goog...lide=id.i0
Blog - http://koffeekosm...gspot.com/

Bezzera Strega, Mazzer Robur Grinder, Pullman Tamper Convex,
(KKTO) Turbo Oven Home Roaster.
 
JackH
Here is a site with a lot of information on wiper motors: http://www.scary-...wipmtr.htm
(They use them for prop animation but the info is great.)

I used this power pack from Amazon for my wiper motor:
http://www.amazon...prod_title

12V 6 Amp pack for about $9.

If you need to vary the motor speed you will need a controller unit that varies the voltage...OR you can run the motor at different speeds by wiring to the high or low speed terminal on the motor and using either a 5V or 12V power pack.

Most wiper motors have two speeds and you can wire to the low or high speed terminals on the motor.

My motor for example:
High Speed @ 12V: 53 r.p.m.
Low Speed @ 12V: 38 r.p.m.
High Speed @ 5V: 21 r.p.m.
Low Speed @ 5V: 15 r.p.m.
 
JimG
Gotta ask: has anyone tried using PWM to vary the motor speed?

Jim
 
oldgearhead
(For DocZ) 12 x 5 x 1.25 = 75VA

Sure. I've used lots of different KB Electronics single board controllers,
both PWM and triac. The big advantage for PWM is the ability to go up to 130 VDC for control of AC/DC (Universal) 120 VAC brush motors. The older triac controllers will only reach 90V.

I run the 1 HP Ametec-Lamb 120V blower on my fluid-bed roaster with a 0-90V KB controller, set-up as follows:
Torque limit = 6A
Min speed = 20v
Max speed = 70 volt

The actual voltage range I use is only 14-35V.

You won't believe how much better control is gained when you upgrade from a dimmer switch or router controller to a drive..
Edited by oldgearhead on 12/17/2011 10:34 AM
No oil on my beans...
 
jedovaty
Jack beat me to it, lcd monitor bricks are usually 12V and range 3-6A. I am using an old network 10/100 hub's power supply, 12V 1.5A and it gives my 1984 300E window wipe motor a spin of just under 40rpm with beans. It was a bit slow so I replaced it temporarily with a diy bench power supply, where we converted a computer's PSU (this is a useful thing to have if you are a diy'er, but caution must be heeded as it could be deadly with live voltage). This one allows enough juice to let the motor spin at about 60rpm with load. Jack - thanks for the link, those are really cheap!

Somewhat relevant question: if you want the motor to spin faster without busting it (e.g. give it more volts, but I think that's not good), can you just add another stirring rod? Let's say you have 2, wouldn't a 3rd or 4th add the extra agitation as if increasing speed?
 
JackH
I was originally thinking that with a BBQ drum, you might not need precise control or the need to vary the motor/drum speed and that one of the preset speeds will do. Not sure because I am not familiar with BBQ roasters. Certainly cheaper using the fixed power packs.
 
DocZ
I was hoping to go down and get something off the shelf, not looking good. I like the PC PSU idea except I sent them out to the recycler without pulling one, who knew. What I do have is Xbox 360 brick that should do the trick DC 12V/12.1A. Just need to find a good mod to get it done. If anybody has link to one please post.
 
jedovaty
To get you started, you should be able to use any power adapters for around-the-house equipment that's 12V and 800mA to 1.5A. My parents have half a dozen laying around from various things like network hubs, old calculators, etc. You can either make a jack for them to plug into, or snip the ends and properly attach them.

Try a local goodwill, they often times may have lcd monitors or other electronics for $10 or less.

I did a quick search on the xbox 360 power adapter, looks like there are three kinds. I found this link on instructables that give syou the pin out. Be super careful please, if you haven't messed with electricity like this before, find a buddy that has... make sure they have a probulator or multi meter or something, too, to verify. My litle brother and a close friend both supervised and taught me what to do to stay safe. If not for them, there'd be roasted jano rump for dinner. Seriously.

Ultimately, you can either use the existing connector on the brick or cut it to use specific wires and make your own plugs.
Edited by jedovaty on 12/18/2011 11:07 AM
 
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