simulate a windshield wiper motor

[Brentusbrutus]

Hi there..
I'm trying to find out what kind of motor i could buy that would simulate a windshield wiper motor. I would like it to run on 2 AA Bateries..
Any help would be appreciated..

[chapter30]

I know the windsheild wiper motors used on cars are very power hungry and may only last seconds (if that) on AA batteries.<p>When you say simulate do you mean something that could push some windsheild wipers or something that will just spin when the wipers should be on?

[Brentusbrutus]

i'm looking for a motor that will turn clock wise, then pause, then turn counter clockwise, then pause, and then repeat....

[philba]

I doubt you will find anything premade. <p>Essentially, you want an h-bridge and a timer (555 will do it). The h-bridge is used to control direction of the motor and the timer is used to control the h-bridge. The timer output of the 555 should go into the direction control of the h-bridge. <p>set the 555 up in astable mode with a period of twice how ever long you want it to run for. You may have trouble getting the duty cycle to be exactly 50%, though. Here's (one of thousands...) a page on using the 555 http://www.doctronics.co.uk/555.htm#monostable<p>You could build your own H-bridge with transistors - look here http://www.mcmanis.com/chuck/robotics/t ... rcuit.html
Or you can use an H-bridge chip. I'd take a look at the L293, L298, LMD18200 or 754410. (the 754410 has integral diodes - makes it easier to use and digikey has it for <$2). Note that you may need to move up to 4 batteries as these all want more than 3V.

[chapter30]

After the control electronics are all set there are other things to think about regarding the motor. <p>What type of load is it going to carry? If it's something like a windsheild wiper you may want to consider a gear motor (Jameco has a large selection of these). If it's lighter than that there are a lot of alternatives.<p>Also, a servo might work if it's only going to turn 60 degrees or so.

[Brentusbrutus]

wow philiba..
I wish I could understand you.. I don't have any background in electronics. I can't even decipher those schematics or plans. Is there a easy to read book to figure thsi stuff out?

[Brentusbrutus]

Jeff: The load it will carry will be about 6 to 20 ounces

[Brentusbrutus]

Hi Jeff..
The Load would actually be around 1 to 10 ounces I am guessing..
And..can you explain more about your servo motor?
I was looking at the motion that the motor from my cd rom maske (just the In And out) and that could possibly work as well..

[philba]

<blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr>Originally posted by Brentusbrutus:
wow philiba..
I wish I could understand you.. I don't have any background in electronics. I can't even decipher those schematics or plans. Is there a easy to read book to figure thsi stuff out?<hr></blockquote><p>oh, never mind...<p>the problem here is that you are off the beaten path and that requires some invention. Invention needs *some* background in electronics. The book "Building Robot Drive Trains" has lots on motor control at a fairly simple level but doesn't explain electronics. I'm sure there is a 555 timer for dummies book or web page out there so its possible for you to figure this stuff out but I fear you will be on a journey that is far longer than you wanted.<p>Wish I could point you to some place that would work for you.<p>Phil

[Clyde Crashkop]

Take a look at the wiper motor/linkage on your car or another one if it’s covered up and you can’t see it. The motor just rotates with pin that is off center moving a linkage back and forth. Any slow or gear reduced motor will do that.
Dave

[Engineer1138]

Pretty much what Dave Hogan said, but I would add that you can search the web and find mechanisms all over the place. It's easier for a non-technical person to understand a mechanical drawing than an electronic one. I believe the windshield wiper mechanism is a four-bar linkage. If you Google for that term you should find something you can build and connect to an ordinary motor to get the motion profile you need.<p>Otherwise, your options are
1) Get ready to learn a lot about electronics or
2) Pay someone who already knows a lot to do it.

[philba]

OK, I think I have a solution for you if you are willing to go with 5 batteries (on 9V for the timer and 4 1.5V for the motor). Get this kit: http://www.electronickits.com/kit/compl ... ck1614.htm
It controls a relay. use mode 5 (toggling) which switches the relay on and then off at a preset interval. Download the manual and take a look. Hook up the batteries, motor and relay output as follows:
- get a 4 battery holder. hook the positive connection to the NC connector on the relay.
- hook the negative bat holder connection to the NO connector on the relay.
- hook the relay center (C) to one terminal of the motor
- now the slightly tricky part. Find the place on your battery holder where the 2nd and 3rd batteries are connected. Connect a wire there and run that wire to the other motor terminal.<p>Now, when the timer runs, it will switch between giving the motor + and -, thus alternating directions.<p>Your requirement of 2 1.5V batteries is actually a big challenge. It could be done with some engineering but its not simple.<p>[ March 14, 2005: Message edited by: philba ]</p>

[Chris Smith]

No need to reinvent the wiper motor action in a electronic fashion. They are stickily mechanical and far more reliable this way. After all, they didn’t have "semi conductors", “stamps”, or “Pics” when they were making the Model T! <p>And even back then, they were hand cranked before the vacuum motors took over, then the electrical motors took over the vacuum motor.<p>The way a wiper works is not that the motor goes left, then stops, and then starts backing up the motor.<p> Its far more simple, Its called a “Bell Crank” and the way it works is very simple.<p> You start off with the motor spinning in a circle at all times and the shaft of the motor had a small lever on it, with a ball socket and feed arm. <p>This socket has a arm that attaches to a longer arm on another shaft that also has a bearings on its shaft and arm. <p>When the motor with its short arm reaches its closest point to the other shaft, the spin brings it back and thus the longer arm never makes a full circle and [the wiper] returns in a sweeping motion of less than 360 degrees. <p>The ratio of the two arms is what determines the sweeping motion of the second arm.<p> For example a one inch arm on the wiper motor and a three to four inch arm on the shaft, produces the typical blade sweep on most cars and trucks.

[philba]

Very good chris. You suceeded in both not answering his question and lecturing about how much better your non-solution was. <p>To refresh your memory, here is what he said "i'm looking for a motor that will turn clock wise, then pause, then turn counter clockwise, then pause, and then repeat...."<p>Note the motor turning clockwise/counter clockwise part. maybe he can solve his problem with a bell crank but that's not what he asked for.

[Chris Smith]

Actually he said "I'm trying to find out what kind of motor I could buy that would simulate a windshield wiper motor." with no mention of its actual function.<p>If all he wants is a sweep then That’s how he should accomplish it. I try not to read minds.