Wiper motor speed control.....

[Gothyc Designs]

I'm sure this has been brought up many times, but I want to know if a controller can be made without needing to take apart a computer or by from Monster Gutz.

I don't think it should be that hard. being a 12v system, what is there available to be used to control the speed? Any how tows or link that anyone can provide would be great. I have looked up making a rheostat, but would like to see something more tangible than those.

ThX.

[hedg12]

A DC motor's speed can be varied to some degree by varying the input voltage. You can usually run a 12 volt wiper motor on 5 or 6 volts at roughly half it's normal speed.

The problem with varying voltage to a motor is that at lower voltages not only do you lose speed, you lose power. A better method would be to use PWM - Pulse Width Modulation - to control the speed. Basically, PWM cycles the power on and off at a given frequency, varying the amount of time it's "on" in relation to the time it's "off". There are fairly simple circuits out there to do exactly what you're wanting to. I'm at work now, so I can't give you any links - I'll post some when I get home tonight.

[halstaff]

Here's the link to the motor controller I used on my FCG which uses a Monster Guts wiper motor and a 12V power supply.
http://store.qkits.com/moreinfo.cfm/MX033
It works great!

[Thisaintmayberry]

The neat little board that Halstaff recommends uses the PWM technology that hedg12 is referring to. I've used dozens of these and they're great. Cheap ($19 last time I checked) and small enough to fit inside anything, even an ATX PC power supply box. The advantage as hed12 referred to, is that you get all of the torque of the wiper motor at any shaft speed.

[hedg12]

I'll post some when I get home tonight.
Looks like Halstaff beat me to it! That little board is great.

[fritz42_male]

Wish I'd known about the QKits motor controller before - I just bought the bits to make a Picaxe based one.

[Gothyc Designs]

Thx Everyone, thats exactly what I was looking for !! Cools, under $20 is def. in my budget and for that price, you can get 3 for the price of what 1 from monster gutz would be. I'm sure they have a good product too. But $60...wow.

I will def. look into this and by the closeup of the circuit board, can easily house it in a mini RS project box.

Last year I did some research and tried to make my own rheostat, it works, but it got way too hot and don't think it could hold a load too much. So obviously I was on the right track if they have something similar out such as this.

Any pointers to know about them before I get any? Any restrictions I should be aware of just in case?

And curious does anyone know what a basic rpm is for wiper motors? Low to high depending on the plugs you use?

ThX again everyone.

Season Screamings !!!!!

[Thisaintmayberry]

From Scary Terry's web page:

Voltage High Low
12 70 rpm 41 rpm
8 42 rpm 28 rpm
5 26 rpm 16 rpm
3.3 13 rpm 10 rpm

Not formatting the way I wanted it but I think you can decifer it.

[Gothyc Designs]

Cools. ThX much. Do you think there would be a schematic showing which prongs do which speeds? Just curious, since I wonder if you would hook this controller up to the highest speed or to any other speeds to fine tune it more.

Generally the prop I was gonna build last year was one of the cauldron stiring props and couldn't get a lower speed, look funny stiring fast, like he's trying to get over the halloween season quickly...lol.

So for those that have used this speed controller, whats a good setting you've used, like 1/2 speed or 1/4 speed. just getting an idea what to expect from this item.

ThX

[Thisaintmayberry]

It seems every wiper motor has a different proprietary hookup. You just have to test the prongs to figure out which one does what. You won't mess up the motor so test away. As far as connecting to the Qkits board, I have typically used the high speed prong on the motor, just to get the most variability with the motor. With respect to your stiring cauldron prop, the great thing about this controller is you can dial down the motor speed to whatever looks good to you.

[Gothyc Designs]

Cools. ThX for the advice. Think I'll be getting 2 for now. Probably won't get that prop done this year. But there will be plenty of play time to get set up for next year.

Actually one more question....How has the longevity of the wiper motors been using these controllers? Does there seem to be any fatigue on them? And sounds like with the controller it'll keep the torque in check so shouldn't have any lagging if a linkage as more resistance on one side more than the other, such as if the arm is going up and has the weight of the prop on it. Things like that.

I can see now having access to a controller like this will make a world of difference in what props I can make now vs. what I couldn't before.


ThX again !!!



.

[Thisaintmayberry]

Sorry for responding so late, it was a busy week. With respect to motor longevity - and speaking only for myself who runs them one night a year - I've not had any motor issues using these controller boards and I've been using them for about 5 years (so I guess that is only 5 days, plus tinker time).

With respect to the "lagging linkage" issue, I have seen a wiper motor struggle on a FCG where the prop body was heavier than normal and the motor was slowed to less than 4rpm. The solution was to hang a counter balance equal to the weight of the prop body which balanced out the linkage pull to the motor.