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Solenoids remaining on.

Hi Jasen, Jonno and those interested,

Sorry not to reply sooner. I was hoping to think of a way to do it like you suggest but have been struggling to do so. What do you suggest to stop the motor at approximately the right time?

One way I thought of would be to have two electro magnets with one on each side of the motor. A magnetic switch could be placed on the rotating shaft. When the sensor came on it would switch on one of the electro magnets and switch the other one off. When the sensor went off the electro magnet that is on would go off and the one that is off would come on. The electro magnet would be placed near the motor shaft so that the magnetic reed switch on the rotating shaft moves close to it. Each electro magnet would be made so that it keeps the reed switch on for a 180 degree turn of the motor. If this method is used we would have to be careful to avoid cable twisting.

If you have any other ideas or a simpler way, please let me know. Are you sure that using crank would be simpler than the other way of reversing a motor, bearing in mind setting up a crank would not be needed for the other way?

Also, I am currently winding up a single strand of thin enamel copper wire and would like to test it as a solenoid as well. The wire is about 0.2 mm thick. I am winding it around a bit of pipe about 12mm outside diameter. At what point do you think it would produce the strongest magnetic force for a solenoid that is running of 12 volts and 24 volts? How many meters would I wind on before I test it? I do not want it to get too hot.

Your help is appreciated Regards Richard

Reply to
richardghole
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I'd use microswitches if you locate them out of the weather they last for millions of cycles, in an application like this: basically forever.

arrange them so that each switch interrupts the current to the motor (ie opens) just as it comes th the point where you want it to stop, wether it stays open for 15 or 150 degrees after it opens isn't really wery critical.

then you supply power via one of the switches to open the louvers and the motor moves until that switch opens (and then everything stops) anw when you want then close supply current via the other switch and the motor runs until that one opens (by which time the first switch has closed again)

open T ----------o | o-----+ ~~~~~ | shut T | ----------o | o-----+----[(M)]----- 0V ~~~~~ the open/shut inputs could be provided by a SPDT relay or the polarity could be reversed and a pair of common-emitter wired power transistors could be used...

for testing I'd use a spdt switch.

I'm guessing: wind until the winding is as thick as the pipe is (this comes fro observing the dimensions of commercial solenoids)

that wire may be too thin for 12V operation..

--

Bye.
   Jasen
Reply to
jasen

Hi Jasen, and those interested,

Thanks for the info.

So do you think that this method would be much easier and less time consuming than the other way of reversing a motor?

Sorry I am not to savvy on electronics. What do the symbols that look like the letters M and T and l mean on the diagram?

How many micro switches would be needed?

I assume that you mean a common micro switch would be all right.

I thought that one switch would have to remain on while the motor rotates through 180 degrees because I thought the motor would have to turn 180 degrees before it stops. I am not sure about some of the other things that you said. However, hopefully I will find someone who can do it.

Do you know of anything made up that can do similar things to what you explain?

What thickness of wire would be best to make a solenoid that is very strong and does not overheat?

Your help is appreciated Regards Richard

Reply to
richardghole

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