jj big shoe Posted April 6, 2005 Share Posted April 6, 2005 Since we have so many engineers and generally bright members, I figure someone could tell me what happens when you apply 12v DC to a 24v DC motor. Does it just run slower or is there going to be damage the motor or the supply circuit? I'm considering a linear actuator to raise the rear window and I might be able to get a 24v one cheap. Thanks in advance. Link to comment Share on other sites More sharing options...
4wheeler Posted April 6, 2005 Share Posted April 6, 2005 I am not positive but i think it will do one of two things. Work slowly, or not at all Im defintely not in that generally bright group. lol :idea: Link to comment Share on other sites More sharing options...
denisb Posted April 6, 2005 Share Posted April 6, 2005 It will just work slower, but your biggest problem might not be voltage as much as power, power window motors are geared down so they have more power. What do you mean by linear actuators? Link to comment Share on other sites More sharing options...
jj big shoe Posted April 6, 2005 Author Share Posted April 6, 2005 This is an electric linear acuator. They also make pneumatic ones. The one I'm looking at is rated for 500lbs. Even at half power It'll do what I need it to do. I'm still kicking the whole idea around anyway so I'm not sure if I'll be using one or not yet. Link to comment Share on other sites More sharing options...
statikuz Posted April 6, 2005 Share Posted April 6, 2005 Haven't you watched enough Monster Garage to know what a linear actuator is? Link to comment Share on other sites More sharing options...
k9sar Posted April 6, 2005 Share Posted April 6, 2005 Haven't you watched enough Monster Garage to know what a linear actuator is? Link to comment Share on other sites More sharing options...
mws Posted April 6, 2005 Share Posted April 6, 2005 I THINK it will work, but at the aforementioned drastically reduced power. But I don't know for sure - depending on the components involved, 12V may not be enough to get the motor to overcome friction and inertia. Once it started, it would probably be fine. And remember, when the engine is running, you should have around 14 volts available. So it's possible it will work with engine on, but not off. My senior research project involved using electric motors designed for 7.2 volts, which we powered with variable power supplies. They would start running somewhere between 3 and 4 volts, depending on the motor and the load. But once running, we could turn them down to about 2.5 and they would keep running (slowly). They would SCREAM at 15 volts. For a little while. The risk of doing any damage is minimal, unless it doesn't start right up. If it doesn't start moving within a few seconds, disconnect the power. Link to comment Share on other sites More sharing options...
mws Posted April 6, 2005 Share Posted April 6, 2005 Oh, and that's assuming it is using a std DC motor with limit switches. Stepper motors are another story... Link to comment Share on other sites More sharing options...
vengeful Posted April 7, 2005 Share Posted April 7, 2005 You can step up voltage with a drop in current. How do you think you can run a 120V Power Inverter off your 12V cigarette lighter plug? As for the actuator itself, you have to make sure to get an internally limited one, otherwise you'll burn up the motor and possibly strip out the gears. For mine, I was thinking of getting a remote actuated release for the latch, and then spring loading the hook, so it pops out a little bit, and then putting some really strong shocks on it so they'll push it up. But I'm not sure if I can get shocks strong enough to do that at the right length. Link to comment Share on other sites More sharing options...
Precise1 Posted April 7, 2005 Share Posted April 7, 2005 (edited) Hmm, linear actuator ??? Kinda like this one ??? It's a functional cut away demo model that I made for a company I used to work for... I'm quite a bit brighter with the mechanics than the electronics, but it seems like everything said so far is right on... Personally, I'd build one for the specific application; it's not hard and a lot of parts are off the shelf. I'd also consider pneumatics. Its better for the application, and if you had an air locker... Consider a cantelever and maybe moment arm for the lifting rather than a direct stroke/travel application. Seems like a lot of work to be able to smell your exhaust fumes, but then I have done a lot of complicated work for VERY silly reasons; finished one today. It was a 3" convex fresnel lense that had a beautiful 'floating bubble' effect depending on your view point and rotation. It's a F-ing neeto shiny thing for a toothpaste box that cost $8K. Anyway, let me know if you want some help... Oh, monster garage is cool, but it is for hacks... Bernard Edited April 7, 2005 by Precise1 Link to comment Share on other sites More sharing options...
TrailChaser Posted April 7, 2005 Share Posted April 7, 2005 (edited) Oh, monster garage is cool, but it is for hacks... Bernard I don't quite understand what you mean by that... For the record I and every welder/fabricator I worked with would luv to be on that show... It's been discussed around the shop many times... Edited April 7, 2005 by TrailChaser Link to comment Share on other sites More sharing options...
jj big shoe Posted April 7, 2005 Author Share Posted April 7, 2005 I want to be able to lift and support the rear glass because with the windows down the turbulence from the air rushing in bugs me. I propped it up one day and noticed it was a lot nicer with the rear window open. I used to do that with my hard top Wrangler and even driving in stop & go traffic in downtown D.C. I didn't notice any exhaust fumes. Plus it's kinda trick and a cool project to try. I'm still thinking about different ways to do it that cost less than a toothpaste box accessory. There's a lot of motors, slides, screw shafts and such lying around my work so I'll start there I guess. Does anyone know where I could get a 3' ball screw-type gizmo that has both left and right hand threads that meet in the middle? Link to comment Share on other sites More sharing options...
Precise1 Posted April 7, 2005 Share Posted April 7, 2005 I was just joking about the exhaust... Yes, there are plent of ballscrew suppliers, but I have never seen (or looked for) any that reversed in the center... Maybe weld 2 pieces together ?? Are you thinking ball screw to keep the friction down ? Otherwise acme thread with oil-lite bronze bushings would work just fine and be cheaper. My apologies TrailChaser, I misspoke. I have only seen the show a couple of times, but yes, it is cool, funny, and a great idea. Am I thinking about the right one, where they build wierd contraptions out of odds and ends to a time limit ? If thats the one, things are generally put together too fast or too mismached to work well. Thats what I meant, is hacking things together, not calling the people hacks; they are obviously quite skilled and knowledgable... B Link to comment Share on other sites More sharing options...
jj big shoe Posted April 8, 2005 Author Share Posted April 8, 2005 Personally, I'd build one for the specific application; it's not hard and a lot of parts are off the shelf. I'm intrigued... Where does one find such a shelf to remove said parts from? I haven't seen this stuff at Home Depot. I'd also consider pneumatics. Thought about it, but running wire or tapping power from the existing ones seems less tricky than running air lines through the lift hatch for me. Like I said this idea is still in it's infancy and pneumatics are definately a thought. I'll have to pull the rear hatch panel off and stare at it for a while until I get inspired. Link to comment Share on other sites More sharing options...
jonathanjdfraser Posted April 9, 2005 Share Posted April 9, 2005 all this talk about electrical mumbo-jumbo makes me wanna talk about my idea, i think i should spill it with you. i am curently in second year mechtronics engineering and working on somethign yous might like. i am currently workin on a motorized cargo cover, using two geared down 12v dc motors, two sensors and a plc. i had a pretty expencive sound system in my truck, and like to hide it when parked at school, hence this idea. so its basically two extendable arms mounted on top of my sub box, by my rear seets, that extend out a black sheet straight out all the way to the hatch, voila, everythign is covered. there is a little sensor on my hatch, and one on my sub box telling the motors when to stop, i have a two button switch to open and close it in my dash.. this project is still in the works, i have it working, but i'mproving it... if you go look at my cardomain website below, you will get an idea of where the positioning of this is.. pics will be comin soon, this summer it will be finished, should be pretty awesome, cause i haven't seen anything like this around.. tell me what you think of the idea Link to comment Share on other sites More sharing options...
jj big shoe Posted April 9, 2005 Author Share Posted April 9, 2005 Cool. Looks like a decent amount of boom back there and your cover idea is pretty slick. I'd be careful of broadcasting security measures, though. You never know who's watching. Link to comment Share on other sites More sharing options...
jonathanjdfraser Posted April 9, 2005 Share Posted April 9, 2005 yea, thats true.. thx man Link to comment Share on other sites More sharing options...
Precise1 Posted April 9, 2005 Share Posted April 9, 2005 Sorry JJ, I'm misspeaking again. By off the shelf I mean purchasing components through places like McMaster Carr, Graingers, AirGas might have some, also MSC. I meant not having to fab or scrounge too much to put it together. If you have trouble finding certain items, let me know and I'll send some links... B Link to comment Share on other sites More sharing options...
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