# Reed Switch Help



## Mwaldmann (Jan 11, 2013)

So I have been dabbling in creating an automatic large loop with one siding that can run two trains. I was given a large quantity of LGB stuff from an old friend and it included several electronic LGB Switched and 12070 units.

I saw in Garden Railways Magazine an article that described how to create a two train loop with a siding. So i saw i did not have the 17100 track contacts and saw they were like $15 dollars a piece - so I went and ordered Magnetic Reed Switches from DigiKey - Sensor Magnetic SPST/NO 10w as recommended some where on this forum.

I hooked it all up according to the diagrams and when the magnetic went over the Reed Switch the Switch motor oscillated. So i cannot figure what i Did wrong. do I need something else to just throw the switch with the Reed Switches? 

Does anyone Have experience with the LGB 12010/12070 setup and ordinary reed switches. Do i need a Diode somewhere?

Any suggestions would be great


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## toddalin (Jan 4, 2008)

Posted By Mwaldmann on 05 Jun 2013 06:52 PM 
So I have been dabbling in creating an automatic large loop with one siding that can run two trains. I was given a large quantity of LGB stuff from an old friend and it included several electronic LGB Switched and 12070 units.

I saw in Garden Railways Magazine an article that described how to create a two train loop with a siding. So i saw i did not have the 17100 track contacts and saw they were like $15 dollars a piece - so I went and ordered Magnetic Reed Switches from DigiKey - Sensor Magnetic SPST/NO 10w as recommended some where on this forum.

I hooked it all up according to the diagrams and when the magnetic went over the Reed Switch the Switch motor oscillated. So i cannot figure what i Did wrong. do I need something else to just throw the switch with the Reed Switches? 

Does anyone Have experience with the LGB 12010/12070 setup and ordinary reed switches. Do i need a Diode somewhere?

Any suggestions would be great 


Yes, you forgot the diode and are sending a/c current to the turnout motors. The LGB reeed switch incldues two diodes (for + and -) and an MOV or such to suppress arc current.


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## Mwaldmann (Jan 11, 2013)

Please forgive my ignorance what is a MOV

so I would need two diodes one for each wire, and i assume that the band has to be in different directions on each one?


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## toddalin (Jan 4, 2008)

Posted By Mwaldmann on 05 Jun 2013 07:28 PM 
Please forgive my ignorance what is a MOV

so I would need two diodes one for each wire, and i assume that the band has to be in different directions on each one? 


MOV - Metal Oxide Varistor. This acts as a supressor to save the reed contacts from arcing. 
Yes. Do you intend to throw 1 or 2 turnouts using the reeds? Most reeds can't take the current of two turnout motors at once.


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## Mwaldmann (Jan 11, 2013)

I plan on doing an alternating Station circuit in my siding.

as mentioned in the LGB 00559 pdf

http://www.champex-linden.de/download_fremddokumente/lgb_00559_explore_the_world_of_lgb.pdf

on page 109. 

So Using two sensors to throw one switch back and forth.

There is one in Garden Railways Magazine that i would rather do, but i am seeing what i can do befoer i get ahead of myself


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## Mwaldmann (Jan 11, 2013)

So i found a diode and attached it and connected up my switch and it works. Now it is to figure out how to alternate the switching with another sensor


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## Dan Pierce (Jan 2, 2008)

You need a diode on a reed switch in the opposite direction on the other track. 

You need one wire to come straight from your power (A/C) to one side of the EPL drive. 

The other side of the EPL gets 2 diodes, in opposite directions. 

The other end of these 2 diodes, 1 to a reed on one track the other to a second reed on the 2nd track. 

Then both reeds (non diode end) get tied to the other transformer output. 

LGB took the time to place 2 reeds in their sensor as they did not know which direction current was needed to flow for your application. Most of the time only one diode was used by the end user.


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## toddalin (Jan 4, 2008)

Posted By Dan Pierce on 06 Jun 2013 04:48 AM 
You need a diode on a reed switch in the opposite direction on the other track. 

LGB took the time to place 2 _reeds_ in their sensor as they did not know which direction current was needed to flow for your application. Most of the time only one diode was used by the end user. 

To avoid confusion, Dan meant to say 2 _diodes_. There is only one _reed_ switch.


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## Dan Pierce (Jan 2, 2008)

My error, you are correct, one reed and 2 diodes are in the LGB unit.


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## Mwaldmann (Jan 11, 2013)

Great... i am going to try it all out this weekend and see if i get it all right

thanks for both of your help.


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## Mwaldmann (Jan 11, 2013)

Is there a particular Diode you'd recommend. I have several 1n4001, 1n4007's are those good enough or should i consider getting 1n5400's or higher.


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## toddalin (Jan 4, 2008)

Any of the 4000 series is fine. IIRC, diode ratings start at 50 volts (4001) and go up from there. The 4000 series can handle 1 amp and that's enough for a turnout motor.


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## Dan Pierce (Jan 2, 2008)

Since LGB used a 500ma power pack, the 1N400x series is fine. 
last digit is reverse voltage rating and I would go for 100 volts or more when dealing with coils such as motors or relays due to back emf adding to the A/C wave. 
So, the 1n4007 would be my choice. Here is the chart for these diodes: 

http://www.diodes.com/datasheets/ds28002.pdf 

1n4001 reverse V is 35, peak reverse is 50 volts. All in this series have a 1 amp average current. 

The 4001 should never be used on 18 volts A/C for rectifying as the A/C peak is 18 times 1.414 and the capacitor being charged is approx 25 volts thus giving a reverse voltage load of over 50 volts. You could use it for clamping a relay coil.


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## Mark_s (Jun 24, 2013)

New to the forum, so please excuse any breech of etiquette here .

I am working on a layout and have some aristocraft switches. As I understand it, I can get them to switch by applying a DC voltage to the terminals, and swap the polarity to make them switch the other way. I also understand that there is a limiter so that I can apply a constant voltage, and the motor won't burn itself out, which should make controlling the switches pretty easy.

My power controller has terminals on the back to supply 12V DC and 24V DC, as well as the track voltage - does it matter if I use 12 V or 24V for the switch motor?


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