single cap on single coil machines

[bmattie]

I'm new to this hobby but i do have some (little) experience in electronics. I see various circuits to control single coil switch machines but they all seem too complex. It can be done with a single capacitor and a spdt switch (I'm actually using a relay). Here is an ugly hand drawn diagram. Of course if a dpdt switch is used you could use other pole for indicator etc.

So what am I missing? (Maybe it's just so obvious that everyone knows it?)

I'm using this on a Kato double crossover
24484
http://www.nscale.org/forum/attachment.php?attachmentid=34837&stc=1&d=1328376994

[BryanC]

Welcome to nScale.net! :welcome:

The reason your image is not showing up is because it is hosted on a site that requires a login in order to view pictures. That simply doesn't work (although it might for someone who has an account there). Either post the image directly or make sure the hosting site doesn't require a login!

[ChicagoNW]

Welcome to the group and into the hobby

The Kato switch motors work using magnetic polarity. The factory controllers sent a blip of DC in one direction or the other. That is why they only have two wires. Many switch control designs focus on the twin coil designs that work on a totally different principle.

We have worked out these simple designs for home brew contollers

http://www.nscale.net/forums/attachment.php?attachmentid=14761&d=1304718291

Are they as complex as the ones you've seen?

[bmattie]

I understand how the Kato single coil works. The capacitor provides the reverse current via it's discharge when the switch is thrown. I do not want to use a momentary switch because I am using a computer to control the system. I use a relay in place of the switch.

when the switch is selected to the + side of the powersupply the current flows through the coil while charging the cap. Once the cap is charged no more current flow and the cap is at full potential. When the switch is thrown the cap discharges through the coil and the turnout is thrown in the other direction. once the cap is discharged no more current flows.
So this circuit does provide the "blip" of DC in each direction depending on how the switch is thrown.

thanks.


Welcome to the group and into the hobby

The Kato switch motors work using magnetic polarity. The factory controllers sent a blip of DC in one direction or the other. That is why they only have two wires. Many switch control designs focus on the twin coil designs that work on a totally different principle.

We have worked out these simple designs for home brew contollers

http://www.nscale.net/forums/attachment.php?attachmentid=14761&d=1304718291

Are they as complex as the ones you've seen?

[bmattie]

I need a non-momentary switch because I'm using a relay. Actually I melted my turnout a bit from a software bug when I was using two relays, one for polarity and one for the "blip".


Welcome to the group and into the hobby

The Kato switch motors work using magnetic polarity. The factory controllers sent a blip of DC in one direction or the other. That is why they only have two wires. Many switch control designs focus on the twin coil designs that work on a totally different principle.

We have worked out these simple designs for home brew contollers

http://www.nscale.net/forums/attachment.php?attachmentid=14761&d=1304718291

Are they as complex as the ones you've seen?

[ChicagoNW]

By adding computer control you eliminate any claim to be looking for something without complexity. Besides your simple control method, you've added a relay and a computer interface.

But if it works it is a good design. It is very much like a circuit I've recently encountered. Would you mind if I redrew it similar to the ones Ive already done in this gallery? http://www.nscale.net/forums/album.php?albumid=481

[CSXRobert]

I've used that same circuit and it works quite well. You can even add LED's to it to show the turnout's setting, like so(the 1000uF cap is for a single turnout, you need a larger cap for the double crossover):

24520

[ChicagoNW]

Do these drawings check out? 24563

[CSXRobert]

Do these drawings check out?
Yes, they do.

[bmattie]

Should mention that the capacitor size is dependent on the coil requirements. I'm using a 2,200uf capacitor for a kato double crossover so it's driving 4 coils. The size of the capacitor doesn't matter as long as it is large enough.The switch can be a regular spdt or a momentary if users prefer. This circuit also provides protection of a coil in the case of a momentary switch malfunction or holding the switch on. Once the capacitor is charged/discharged no more current flows through the coil.


Do these drawings check out? 24563

[bmattie]

One other note on your drawing. I think showing a double coil may be confusing to some users. The kato is a single coil and if it's a crossover then the coils are actually in parallel but unless you open it up you really don't see that. Just my 2 cents.


Do these drawings check out? 24563

[ChicagoNW]

I started the series of drawings when I was explaining how to convert a Tomix switch from manual to remote control. If you look closely at the drawing you'll see the coils are wired as if they are one. Here's a gallery devoted to switches http://www.nscale.net/forums/album.php?albumid=481 For comparison Kato uses one coil that is between two magnets. The Tomix switch uses one magnet between two serial coils. But both use the same principles of operation. Actually since the Kato and Tomix switches are concerned with the polarity of the magnetic field not the amount of power going through the coils. The larger capacitor just takes a longer time to charge.