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Discussion Starter #1
I'm using a wiper motor with a PWM, and a 110-240V AC to 12V DC 5A Switch Power Supply, for my cauldron creep stirring action. Here's the PWM I have: http://www.amazon.com/gp/product/B005UTBGIG/ref=oh_aui_detailpage_o03_s00?ie=UTF8&psc=1
and here's the power supply: http://www.amazon.com/gp/product/B0026SUMNY/ref=oh_aui_detailpage_o02_s00?ie=UTF8&psc=1

I'm not going to be able to even have my brand new cauldron creep running in my yard because when I slow it down to about 20 rpm, which is still slightly faster than I'd like it, I get this horrible fast pulsing whine. The slower I go, the deeper and louder the whine. Still, anything below about 35 or 40 rpm is so loud it can be heard three houses down. I've tried it with two different motors; one being a wiper motor, and the other a window crank motor, which looks like a smaller version of a wiper motor, and still get the same results. In fact, the smaller motor is even louder. I've also tried a smaller 12v DC 500ma wall wart hooked to the PWM for power, but still got the same results.

Before trying the wiper motor, I did have one of the NEW vent motors in there, but it's waaaaaaaay too slow, at only about 3rpm, so I popped in the wiper motor and PWM board today. The old style vent motors were just fast enough, but I don't have any more of those to use. Is there any way to either speed up the vent motor, which would be my first choice, or to slow the wiper motor and not have the horrible noise involved? Or, should I be using a different motor setup altogether? Please help!
 

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In my experience with the vent motors the speed was close to the same so it could be your power supply is not putting out the 12v but...

with the new vent motor it's safe to use up to 24v and when you go up in volts the speed increases...maybe 1 to 3 rpm. Which is what you are looking for. If you have a 18VDC power supply try it.

As for your wiper motor make sure you are hooked up to low speed that might help because you wont need to reduce the speed as much. One other thing not all wiper motors are the same. I use to use maybe 20 a year in props and I found different models can work on different amps. So if you can find a 12 or 5 vdc volt power supply with 1, , or 3 amps (I've used a 1.5 amp to run a FCG one year with a wiper motor) it might slow it down...depending on the load on the motor.

But since you have the vent motor I would go with that. One other thing I just remembered...the new vent motor runs faster in one direction than it does the other. Maybe 1 or 2 rpms so reverse your wires from the power supply
 

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Discussion Starter #3
I was not aware that the vent motor ran faster in one direction than the other. I'll definitely play around with that, and look around for a higher voltage power supply. I have tried a couple of different 12v power supplies with the wiper motor, and still no reduction in the sound created by the PWM. I don't believe my wiper motor has a slower speed since it only has two leads, a positive and a negative. There aren't multiple leads like with a lot of units. I really appreciate the input, and I'll see what I can accomplish with the vent motor. Thanks a bunch.
 

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I thought maybe you were getting controller whine but then read you still get it without the controller? Do you have a 6 or 12 volt battery to run the motor on without a controller to see if noise goes away? A lot of motor controllers have a squeal at low RPM's and that includes up to high voltage Curtis controllers for electric cars so if this is your issue there may not be a good fix for that motor (most likely the controller) but I was wondering if you could do a gear ratio change via sprockets/pulleys to bring the motor RPM up. Sucks to put time into props and not have them run as intended so wishing you the best.
 

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Yes, this definitely sounds like controller hum. Wiper motors seem to present the sound quite loudly. I've heard it too with a PWM controller I was playing around with. Anything from about mid-speed on down it gets way too whiny to be of any use, especially in quiet props. Try 5 volts from a PC power supply. I used that for our pirate ship steering wheel and it worked pretty well.
 

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Discussion Starter #7
Creepy Creations, I don't have a PC power supply to use, and don't really know anything about converting them for use anyway, but I might have a lower voltage wall wart laying around. I can give that a shot. Also, is there another type of inexpensive speed controller that won't create that sound? Thanks for the advice.

31st Street Haunting, no I don't get the whine without the PWM controller. Of course I can't slow the motor down without the controller either. Without a controller the only noise I get is the usual wiper motor whine, which isn't too horribly loud, but of course the motor then runs too fast. From what I'm reading, it seems like a common problem caused by the PWM controller itself, when used with wiper motors. If I can't get my vent motor to run fast enough with a higher power supply, then I'll try slowing the wiper motor with a lower power supply. Thanks for all the info. Much appreciated.
 

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I've had good luck using a 6 volt golf cart type battery (and a trickle charger to keep it charged) as a power supply for slow motor voltage needs. I have a couple props that used to use controllers and now just run at 6 volts with an on/off switch (and a fuse 8^) Not the cheapest nor lightest option but they can be obtained used and have enough life for us home haunters (old solar batts are great to get a hold of). Just throwing out ideas in hopes you can get it working without it sounding like something's killing it. My only other idea is to look into a small 10:1 gear drive so you can crank the RPM's up on the motor. In truth a DC motor doesn't like to lug at real low RPM's (even though that's where their highest torque is at) and are "most" efficient in the 2-4K RPM area depending on design. Again, hope this at least plants some seeds that'll come to fruit.
 

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I've had good luck using a 6 volt golf cart type battery (and a trickle charger to keep it charged) as a power supply for slow motor voltage needs. I have a couple props that used to use controllers and now just run at 6 volts with an on/off switch (and a fuse 8^) Not the cheapest nor lightest option but they can be obtained used and have enough life for us home haunters (old solar batts are great to get a hold of). Just throwing out ideas in hopes you can get it working without it sounding like something's killing it. My only other idea is to look into a small 10:1 gear drive so you can crank the RPM's up on the motor. In truth a DC motor doesn't like to lug at real low RPM's (even though that's where their highest torque is at) and are "most" efficient in the 2-4K RPM area depending on design. Again, hope this at least plants some seeds that'll come to fruit.

Years ago Big Lots sold a $5 trickle charger that put out 12vdc at 1amp and I used that to power my wiper motor for my FCG...got it down to 6 rpm under the load of moving my FCG. I had other wiper motors that it wouldn't run at all. Of course load has a lot to do with it also.

ryanlamprecht I still have a couple of the new vent motors that has a stripped gear but still turns under no load and I have a large box with 50 or more power supplies. Later today I will test a few to see if I can get the speed you want. If I can find one you are welcome to it. No charge for the power supply (if I can find one that works) or shipping but I will need to paypal invoice you for $1 so I can print shipping through paypal. I will send you a PM if I do with a video clip of the movement

One other question about the vent motor you're using.. is the 3rpm without load or under load (installed for movement in your prop)? Sometime the load (amount being moved) will slow a motor down.
 

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Discussion Starter #12
No, you're thinking of a fan/blower motor that runs the squirl fan. Were talking about the vent motors that opens and closes the vent/flap which controls the air mix in your car's interior. They're a little gift from God to us Halloween folks. Here's a picture of the old style vent motor and one of the new style motor.
old vent motor.jpg new vent motor.jpg
 

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All PWM controllers will generate this type of noise in one form or another. Some are just much quieter than other. Part of it is the frequency that they run at. Cheaper ones run at lower frequency, since typically the frequency doesn't impact the performance of the device very much, but the noise is more audible. They are cheaper to build that way. Big surprise. LOL
 

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I have had the same experience with PWM controllers and wiper motors. I use either a ATX power supply or a 5A AC/DC converter with good results and no noise. It's one of those things you learn the hard way.
 

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Discussion Starter #16
Problem solved!!! At least for this prop. I didn't have a lower voltage power supply laying around like I thought I did, so I went to Walmart and picked up one of those universal wall warts with the voltage selector on it, from 3v up to 12. Did away with the PWM, hooked up the power supply, switched it to 6 volts, and presto. The motor now runs at the perfect speed with no noise. Lesson learned! I really appreciate everyone's help. You've saved me from ripping my hair out. Okay, I haven't had hair for twenty years, but if I did, you'd have saved me from ripping it out, and looking like..., well... like I do now. Seriously though, I put a lot of work into this prop, and thought it was all going to be for not. I'm so glad I belong to this forum. You folks RULE!
 

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I'm using a wiper motor with a PWM, and a 110-240V AC to 12V DC 5A Switch Power Supply, for my cauldron creep stirring action. Here's the PWM I have: http://www.amazon.com/gp/product/B005UTBGIG/ref=oh_aui_detailpage_o03_s00?ie=UTF8&psc=1
and here's the power supply: http://www.amazon.com/gp/product/B0026SUMNY/ref=oh_aui_detailpage_o02_s00?ie=UTF8&psc=1

I'm not going to be able to even have my brand new cauldron creep running in my yard because when I slow it down to about 20 rpm, which is still slightly faster than I'd like it, I get this horrible fast pulsing whine. The slower I go, the deeper and louder the whine. Still, anything below about 35 or 40 rpm is so loud it can be heard three houses down. I've tried it with two different motors; one being a wiper motor, and the other a window crank motor, which looks like a smaller version of a wiper motor, and still get the same results. In fact, the smaller motor is even louder. I've also tried a smaller 12v DC 500ma wall wart hooked to the PWM for power, but still got the same results.
Interesti
Before trying the wiper motor, I did have one of the NEW vent motors in there, but it's waaaaaaaay too slow, at only about 3rpm, so I popped in the wiper motor and PWM board today. The old style vent motors were just fast enough, but I don't have any more of those to use. Is there any way to either speed up the vent motor, which would be my first choice, or to slow the wiper motor and not have the horrible noise involved? Or, should I be using a different motor setup altogether? Please help!
interesting Problem....
 

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I went to Walmart and picked up one of those universal wall warts with the voltage selector on it, from 3v up to 12.
I'm glad that solved your problem, but I'm curious: is that wall wart powering the vent motor, or the wiper motor? Because I wouldn't have thought that a wiper motor would operate off of a little selectable wall wart, since the maximum current's usually pretty low. Anyway, if you run into any other problems and need a PC supply ASAP, shoot me a PM; I'm just up in Mesa, and I've got plenty of PC supplies lying around.
 

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I learned about a new motor type to keep my eye out for as well. Congrats on a passing grade from the school of hard knocks, once you've learned something there, you typically don't forget it. As noted above keep an eye out for heat in the cord and unit if using the larger motor.
 

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Quick question before this thread fades to the dustbin of prop help paraphernalia, are people using the vent motors continuously or just intermittently as far as a duty cycle/run time? Thanks for the pics BTW 8^)
 
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