Can you reverse a non-reversible motor with the HB-25 motor controller?
latigerlilly
Posts: 114
Hi Guys,
I just bought 4 HB-25 motor controllers. I was wondering, can you reverse a non-reversible windshield wiper motor with a HB-25 motor controller? Here is the motor I would like to use: www.meci.com/advanced_search_result.php?keywords=420-0578&x=15&y=7 .
Thanks,
Lilly.
I just bought 4 HB-25 motor controllers. I was wondering, can you reverse a non-reversible windshield wiper motor with a HB-25 motor controller? Here is the motor I would like to use: www.meci.com/advanced_search_result.php?keywords=420-0578&x=15&y=7 .
Thanks,
Lilly.
Comments
crgwbr
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NerdMaster
For
Life
· If you look back at your first post on building a wheel chair I posted a link to a web site that sells surplus motors, they have some 24 volt wiper type motors ( I run them at 12 volt with no problem) and they have a nice shaft to mount gears or pulleys. heres a picture.
Brian
Ps , Heres some nice motors, a little more money. But they look like they are made for what your doing.
http://www.surpluscenter.com/item.asp?UID=2007013007470748&item=5-1623&catname=electric
Post Edited (Brian Beckius) : 1/30/2007 1:55:25 PM GMT
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The·wiper motor in the link you gave appears to·be reversible. Just give it a go with a 9V battery.
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Bear in mind that most·wiper motors are·negatively grounded.·Therefore, you cannot·run two motors·in opposite directions, at the same time,·if mounted to a metallic chassis.·
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If necessary, you could bypass the·'cycle switch' on the main gear and solder leads directly to the motors brushes, this should eliminate the grounding problem as well as the direction of rotation.·
Hope this helps.
Chris
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······ " There are 10 types of people in the world:
··········Those who understand binary, and those who don't... "
- www.timesecret.de
ChrisE,
the motor is non-reversible. Here's some info: www.skycraftsurplus.com/index.asp?PageAction=VIEWPROD&ProdID=760 . As for the grounding problem, I have no idea what you're talking about. I was not going to connect ground to the metallic chassis. I was going to connect the positive from the power supply to the "high speed terminal" and the negative from the power supply to the common (ground) on the motor per this illustration www.scary-terry.com/wipmtr/wipmtr2.htm . I also have no idea how to take apart a motor to solder directly on the brushes. So, I guess I'll have to use something more expensive than a windshield wiper motor.
Brian Beckius,
Actually, you and another forum member had already suggested that website. However, I hesitate to buy any parts that are used/surplus because these parts are not well documented. I am not a tinkerer because I cannot afford to tinker (I am 17 yrs old and my budget is limited). Therefore, I design and plan everything before I purchase any parts. I called the guy from the Surplus Center website and asked him if what the maximum HP rating on the motor is and he said, "I dunno." I did not want the motor to overload the Parallax HB-25 controller which has a max HP rating of 0.5 HP. So, I asked him what the stall amp of the motor is and he said, "I dunno. All I know is what's printed on the website. It's 2.5 amps with no load." I did not want it to overload the HB-25 maximum 25 amp load and 35 amp surge rating. So, that's why I try to avoid poorly documented surplus/used parts in favor of new parts. There are too many unknowns. I also did not know that you can power a 24 VDC motor with 12 VDC. I wasn't sure if it would spin if powered by an off-spec power source. Thank you for teaching me this valuable bit of knowledge (I learn something new from you guys every day!). Anyways, which motor are you using in your picture (do you have a part number)? Is this motor reversible? I like it because it has a nice long shaft for ease of mounting sprockets, pulleys, etc.
Thanks a bunch guys,
Lilly
This pesky grounding stuff, etc., is something you'll need to come to grips with. If you don't understand proper grounding (or isolation from ground), you'll sure to have some 'excitement', either with (relatively) large components like motors, or with letting the magic smoke out of electronic parts.
In the case of your selected motor, there is "non-reversable" and there is "non-reversable".
This motor is most likely reversable, but not in the intended application (automotive). It is most likely (although not absolutly) a motor that is reversable, but is set up so that one of the brush leads is connected to the motor case/chasis.
In an automotive application, the chasis of the motor will be connected mechanically to the automotive chasis, and this is "Ground" (at least in "modern" vehicles), or the negative terminal on the battery.
There are a couple of positive connections on the motor, one for high speed, and one for low speed. These connect to the other brush, probably with the low speed going through a resistor, and or through partial field windings.
In order to reverse the motor, you would need to make sure that it's case, and any attached parts, including gear boxes, levers, shafts, etc., are "isolated" from ground. This may be a non-trivial task, and may, as you indicated, make this motor an impractical choice for your application.
If you could fully isolate the motor and all parts, then you could probably (not absolutely) reverse the motor.
The "gotcha" would be with respect to how the high/low speed is handled, and internal connections may be made between various electrical parts and the motor case (Ground).
If you are leary of used parts, you could still look at automotive parts. Besides wiper motors, you could also look at power window motors (some of these have very userful gear boxes already built in), as well as power seat motors. There are also dozens of other smaller motors in a modern automobile.
Seat and window motors are set up to be reversed, and shouldn't be that much more expensive than the wiper motors (he said with his fingers crossed).
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John R.
8 + 8 = 10
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- Stephen
Sorry to say you have 2 choices , spend the big money and get the documentation or go surplus and make your own documentation.Theres a good article in nuts & volts this month about how to verify what a motor is capable of . About that motor in my picture that came from surplus center and I am looking for a part number. Also ,I don't believe that motor in link I gave you is anywhere near a half a horse (you should not have a problem powering it with a HB-25).By the way if you where to buy that motor with documentation it would probally run you about $300.00
Brian
Now you have me worried. So, you're saying that I cannot just connect the two terminals of the motor to the two terminals of the battery and go? I'll have to connect to "ground"? I thought one of the battery terminals is "ground"? I really cannot afford to fry my electronics. I cannot afford for that to happen as I am an unemployed 17 yr old. If there's an online tutorial explaining what you mean, I'd really, really, (really) appreciate it. As I am being homeschooled in rural Texas and I've surpassed my parents' math/science abilities, you guys are my teachers (thanks!).
I read somewhere that in a large vehicle, the ground is the metal vehicle body. If that's so, why do you still hook up the car to both your car battery's + and - terminals? I mean, if the car body is ground, why do you hook up the car's electrical stuff to the ground on the battery? I also read that you don't have to hook up an electrical system in a car to the ground below your feet because the car body is so big that it can serve as the ground. Isn't a 100 lb robot chassis too small to serve as ground? If I need to connect the robot to ground, how would I do that? In other words, if I need to connect to something other than the + and - terminals on the battery, how would I do that? Do I need to do that?
Thanks,
Lilly.
To simplify things, in an Automobile they designate the frame as "ground". And yes, if you look in your car there's a "grounding strap" that connects your frame to the negative terminal of your car's battery.
This means in a car you only have to run ONE wire to a light, or your radio, or whatever, because the car frame provides the 'second wire' to ground.
Now, car devices (like a wind-shield wiper motor) will have been engineered this way. If you're NOT using automotive devices, you don't have to worry about things like this, you'll have to connect both a Plus and a Ground wire.
Ah -- except for when you're controlling an electric motor using an H-Bridge device, like the HB-25. An H-Bridge lets you feed current through a DC motor in BOTH directions (not at the same time) so you can 'reverse' the motor. So when using an H-Bridge, you don't actually connect the motor to Ground at all -- you connect one terminal of the motor to one side of the H-Bridge, and the other terminal to the other side of the H-Bridge.
I'm really concerned, if you're trying to help your friend, and use these high-horsepower motors, that you're still asking these very basic questions where motors are concerned. Though you are limited in cash, I strongly encourage you to build a small prototype and get that to work and work out the principles involved. THEN, having validated the techniques and code, you could upgrade to a full-power full-scale solution.
Otherwise, I fear you're going to waste a lot of money on several full-power full-scale solutions which either aren't going to work, or are going to hurt somebody.
"Ground" in the sense we are talking is not "ground" in the sense of your home electrical system "ground" and not the "earth" ground. "Ground" in this sense is "common" and in automotive applications, is the chassis. It can also be the chassis in a robot application.
The reason that you still connect both wires (positive and negative) in some cases, especially high power applications like motors, on a car is that the mechanical connections don't always make good conductors of electricity. They become rusty and dirty, and can vibrate loose. The "ground" wire, or negative connection is made to assure a good connection. Making sure that everything is "grounded" to the chassis is also part of minimizing electronic "noise" that can affect your radio and other electronic components in the car.
When building a robot, you may want to do things differently, for example isolating the motor and running both negative and positive connections. Note that in the case of the motor you had selected, this would including finding a way to "isolate" or "insulate" the shaft or any output linkages.
I share an alliance with alliance5 in that you seem to be trying (more power to you) to build something beyond your current "comfort zone". We all have to grow, and this (trying new things) is how we grow. Trying these types of large scale projects is not the best way to start, and especially dealing with a (at least partially) disabled user, "the consequences of failure could be extreme".
I'd suggest this as a possibility for a learning excercise: Go to Radio Shack, or your local Toys R Us or someplace like that, and look in the Radio Controlled toy area. Find something "big" like a truck or "sand box toy" that is motorized, but not so big as a "ride on" toy. Ideally, it will be something that doesn't move all that fast (it's easier to catch that way). It can be eithe rRadio controlled, or with a "tethered" control. I think you should be able to find something for less than $100.00, and maybe as low as $50.00 or so. You don't want something too small. Ideally get one with a variable speed and "proportional" steering.
When you have that, take it home, get out the tool box (and maybe a knife or saw), and open that baby up. Now start to look around and see how things are connected. Find out where the components are that control things, and where the parts are that "do the work" (motors, steering, etc.). Then start to see where you can cut some wires, and substitute your own controls. You can start with simple on/off switches, and change over to a small "H" drive powered by a stamp. Depending on how lucky you are, you may even get a toy with some "H" drives in it. There are places you can go to look up chip numbers, etc., and even web sites that specialize in how to "hack" into various toys.
Speaking of which, that might be a good place to start, before you buy a toy/model, go "window shopping" and get a list of options. Then go back to your friend google and look up "hack MyToyName" (without the quotes) and see what you get. If you find a site for a toy you can get with good "instructions", then you might get a jump start.
While I think it fair to say that everyone applauds your efforts, we don't want to see you bite off more than you're ready to chew. As much as you want to jump in, it may be time to slow down, and get an understanding of some of the fundamentals involved first. While this may take some time and money, this approach can help save money in the long term, and in this case possible injury or property damage (fire with the size and type of device is a distinct possibility).
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John R.
8 + 8 = 10
I'm going to have to side with everyone else here and say procede at your own risk , You are working with to fragile of cargo to be not a 100% sure if somthing works or not . I think you should start with a small protype and then work up.
Brian