Gear Motor for Moving Window Display

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Old 11-11-13, 07:12 PM
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Gear Motor for Moving Window Display

A friend commissioned my DIY confidence to help design a moving window display to use in her store front throughout the holidays (on a budget). She has knit ten little 6" characters that she wants to suspend in front of a decorated tree. My job is to hopefully make them bob up and down. I sketched out my idea for a pulley system:

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Attach a motor to a plank of wood mounted above the window. Attach an arm and grooved post to the motor. Loop a strong thread or wire around the (lubricated) grooved post, down through hooks spaced along the plank, and to the characters. Movement of the arm would lengthen or shorten the lines and raise or lower the characters. I could even wire in "pivot" hooks on either side to alternate the up/down movement of each character. I feel pretty good about this pulley system, though comments or concerns are always welcome.

What I came here for is electrical advice. I happen to have laying around a perfectly good windshield wiper motor from a 2004 Toyota Camry, and if possible I'd like to incorporate it into the project. It has a 3 pin connector, I assume 12V, signal (5V?), and ground. Here is where my knowledge of wiper motor circuits gets hazy. Obviously the motor is able to turn both intermittently and at multiple speeds. Although the intermittent feature would be nice, I assume it is controlled by intermittent signals from the vehicle's control unit, which is probably beyond the scope of this project. Control over the speed of the motor, however, will be necessary. How is the speed controlled? Can you feed less voltage to either pin to drop the rpms? Is it incremental, or infinitely adjustable, and is there a lower limit?

In the event that my wiper motor might actually work, how would I go about feeding it power? I remember playing with adjustable 12V power sources in tech school, are they available and affordable? Safe to run 8-10hrs daily for a few weeks?

All suggestions and alternative ideas/designs are more than welcome. Thats why I'm here. Thanks.
 
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Old 11-11-13, 07:31 PM
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Welcome to the forums.

Clever idea on the display

I'm not sure if the windshield motor is the best choice. It's a brush type motor and I don't think it will last that long running that many hours. I could be wrong... just my opinion.

The three wires to the motor are probably ground, high speed and low speed. You may be able to slow it down but it may stall at too low a speed.

I would look into a smaller gear driven system like I've left you a link for. That is a 2 rpm speed motor but at the bottom of the page are many different speeds to choose from.
12VDC 2rpm High Torque DC Worm Gear Motor with Gear Reducer Gear Box | eBay

As far as speed control you could use a PWM DC controller. The same company in the link above sells them.
12 24VDC 240W PWM Speed Controller for DC Motor | eBay
 
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Old 11-11-13, 09:33 PM
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Wow, what a prompt, quality response! Thank you. I figured the one random motor I happened to already have most likely wouldn't be ideal for the project, but it was worth a try. From what I could find on the internet, motors and controllers like the ones you recommended were my next guess. However, without any personal reference for size or speed and with the vast selection of ratings available, I was getting a bit ahead of myself.

I really appreciate your suggestions. Looking at them helped me better understand the rating system. Shipping from China could potentially push my deadline, so I'm looking for a domestic source. Also, I think I like the option of having a few more rpm available. This one and this one appear to be comparable, plus they're available sooner. If they're good options I'd like to go with that source, but I'm having trouble finding a comparable speed controller in their selection. Am I missing something? Or do you have a go-to domestic supplier?

Once we wrap that up, I foresee one more thing I'd like to clear up: the 12V supply. I think I'm looking for one of these? Should the amperage rating correspond to that of the motor? And safety is always a concern, just want to be sure.
 
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Old 11-11-13, 10:59 PM
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Sorry about spec'ing off shore components. I didn't read the ad carefully enough.

Either of those motors looks good. The second one..... 6 rpm's should be a good.

I checked their site and didn't see any speed controllers. There are a million on eBay. Go to the search bar and enter "12vdc pwm"

As far as power supplies there are many in that link you left. Something 12vdc at 1 amp or better would be a good match.
 
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Old 11-12-13, 04:50 AM
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Awesome. Thanks again for your guidence!
 
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