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latching pushbutton help

Minder

Apr 24, 2015
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50rpm should be possible, the problem is with motor control is if the load varies, without a feedback element of some kind it is usually hard to control rpm if the load varies.
M.
 

iKatoz

Nov 28, 2015
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No need to be precise, if i need too adjust the speed I can use a potentiometer instead of the resistors
 

Tha fios agaibh

Aug 11, 2014
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I think it depends on the torque you require.
50 rpm is awfully slow, might be better to use gear reduction.
What's the application?
 

iKatoz

Nov 28, 2015
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Yes I know but it's expensive
The motor drives a crank-connecting rod mechanism
 

BobK

Jan 5, 2010
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If your range is 50 to 200 RPM you should use a gear motor that already has a max a little above 200. Slowing down say a 3000 RPM motor to 50 RPM will not be optimal. The gear reduction means a motor with much less torque (hence smaller, cheaper) can be used, because the torque increases in the same ratio as the speed is reduced.

Bob
 

Minder

Apr 24, 2015
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I think it depends on the torque you require.
50 rpm is awfully slow, might be better to use gear reduction.
The torque of a DC motor is usually maximum at zero rpm and stays fairly flat over the rated rpm range, but I agree a reduction of some kind may be an advantage, depending on the present torque required.
M.
 

iKatoz

Nov 28, 2015
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I remade the schematic, I hope that this time is more understandable. I drew only 2 relay because I have no time but the concept is this.

I forgot to specify that those are bistable relay
 

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Tha fios agaibh

Aug 11, 2014
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I don't see how that's going to work.

I'm not sure what bistable relay your talking about, but any latching type relay that requires power to un-latch it, is not a good plan.
The common way to do this safety is to use an open "holding" contact across the open pb contact, and a closed contact on any pushbutton that will kill the circuit, as well as killing the circuit if power is lost.

Besides, I already sketched the circuit in an earlier post.
 

iKatoz

Nov 28, 2015
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I tried.

however, I did not fully understand the circuit. I also tried to simulate it but I can't make it work.

First things first: L1 corresponds to + and L2 to -?
 

Tha fios agaibh

Aug 11, 2014
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Pushing button will energize coil.
Once coil energizes, relay contact closes and shorts across push button contacts.
This lets button to be briefly pushed and relay coil has continuous power.
Once you understand, we will move on.
 

(*steve*)

¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd
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Jan 21, 2010
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ok, I want to use this motor, it is possible to slow down to 50 RPM?
http://it.rs-online.com/web/p/motori-cc/2483671/

Highly unlikely, and certainly not if you want it to drive any sort of load.

Have you considered a gear motor?

What are you actually trying to do? If we can be told what your intended purpose is (rather than what your proposed solution is) we may be able to suggest something which will work.
 

iKatoz

Nov 28, 2015
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Pushing button will energize coil.
Once coil energizes, relay contact closes and shorts across push button contacts.
This lets button to be briefly pushed and relay coil has continuous power.
Once you understand, we will move on.

I understood this but if I press the button opens the negative part of the circuit and the coil never get energized


Highly unlikely, and certainly not if you want it to drive any sort of load.

Have you considered a gear motor?

What are you actually trying to do? If we can be told what your intended purpose is (rather than what your proposed solution is) we may be able to suggest something which will work.
http://it.rs-online.com/web/p/motoriduttori-cc/4095232/
this isn't good?
 

Minder

Apr 24, 2015
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That is a gear motor and is 235rpm, 4mm shaft with 10Ncm torque,
Have you measure or estimated the amount of torque you need?
M.
 

Tha fios agaibh

Aug 11, 2014
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I understood this but if I press the button opens the negative part of the circuit and the coil never get energized

Oh, you are right. They do make switches with a make and break delay, but yes, that circuit won't work.
 
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