Building my own LGB 1700 replacements

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birk_man

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I'm cobbling together replacement contacts from old LGB 1700s with burned out reed switches. I'd like to build some using new components and have not figured out what the specs are on the varistor that is included in some models of the LGB 1700.

Does anyone know what they need to be and where I can buy in small quantities?
 
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korm kormsen

korm kormsen

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i just went to a place, where they sell materials for electronic repairshops, put an open LGB reed switch on the counter and asked for a dozen of each component.
what they sold me works.

 
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birk_man

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i just went to a place, where they sell materials for electronic repairshops, put an open LGB reed switch on the counter and asked for a dozen of each component.
what they sold me works.

I found that photo on your website and it inspired this project - thank you for leading my thinking into new areas!

Where are you located that you have a shop like this 'nearby'?
 
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birk_man

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i just went to a place, where they sell materials for electronic repairshops, put an open LGB reed switch on the counter and asked for a dozen of each component.
what they sold me works.

Varistor VE07-250 25V 50A, try eBay.....
I didn't find anything that seems like a close match on eBay. Is there anything in this mess that would do the job? There seem to be a lot of visually close options in the 250A range.

 
korm kormsen

korm kormsen

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Where are you located that you have a shop like this 'nearby'?
Greg is right. i live in the Paraguayan Chaco, in the center of Southamerica. the shop, where i bought, is in the capital, about 300 miles away.

ps: another idea to replace LGB reeds.
a friend gave me some reeds from house-alarm systems. but i did not try them out yet.
they would have the advantage to be closed. if these reeds (for 24 volt) would play ball, they would need just an added diode or two (as needed)
 
korm kormsen

korm kormsen

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birk_man

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Here are some photos showing the codes on the varistors I found in the original LGB 1700 track contacts and one shot of how I am using the pieces to build a new contact with a more robust reed switch.

I'd appreciate any help in identifying the codes on the red and yellow varistors so I can find matching components to buy.

Thanks so much!

-Peter
LGB 1700 Varistor _2.jpg LGB 1700 Varistor _1.jpg LGB 1700 replacement contact.jpg
 
korm kormsen

korm kormsen

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seeing your pic, i just remember, that then, the seller told me, he didn't have the exactly same parts, but that those shown above (under "AT LAST!!!! ") should do the job.
and they did. for six years, till a move caused dismantling of the layout.

i did not include the diodes into the homemade 1700s. i just screwed or soldered one (in the desired direction) to the outlet of the reeds. (saving a lot of work on more than a dozen reeds!)

ah, something else. the size of the reeds did not make any difference. what did, was the number of switch motors served by one reed. those serving two or three switchmotors did burn closed sometimes.

i think, i will shamelessly steal your idea to use plastic sleepers. (for the more than 20 reed contacts i'm going to use, that will save a lot of work)

btw: if i ever will update/rewrite that page of my website - may i use your photo above?
 
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Greg Elmassian

Greg Elmassian

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This is a common part, and the specs are not so important.


You are just trying to protect the contacts from burning and transients, but they eventually go, if you are trying to switch an inductive load of any current, the reeds will eventually burn.

The emphasis here has been these varistors, but they are not magic, and the emphasis should be on a heavy duty, high current reed, the working part of the circuit, and something ALREADY designed to handle "tough" loads.

Greg
 
korm kormsen

korm kormsen

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... the emphasis should be on a heavy duty, high current reed, the working part of the circuit, and something ALREADY designed to handle "tough" loads.

Greg
do i understand right, that i should use the biggest/longest reeds, that enter into the space between wheels/rails?

and/or would it make a difference in functionality, if i would mount the reeds paralell to the rails, not paralell to the sleepers?
 
korm kormsen

korm kormsen

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Greg, thank you for your helpfull answer.
 
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birk_man

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The emphasis here has been these varistors, but they are not magic, and the emphasis should be on a heavy duty, high current reed, the working part of the circuit, and something ALREADY designed to handle "tough" loads.

Greg
Here is a link to the reed switches I am currently using and that were shown in my photo earlier in this thread.


I ordered them in 2014 and have not had one burn out yet. It's a pretty beefy reed switch compared to what comes in the LGB 1700 yet it is still small enough to conceal inside one of the plastic ties on LGB track. I have neodymium magnets on the bottom of my locos to trip the contacts and they have enough 'reach' to close the reed switches down inside the ties.

1577431197793.png
 
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Greg Elmassian

Greg Elmassian

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Here is a link to the reed switches I am currently using and that were shown in my photo earlier in this thread.


I ordered them in 2014 and have not had one burn out yet. It's a pretty beefy reed switch compared to what comes in the LGB 1700 yet it is still small enough to conceal inside one of the plastic ties on LGB track. I have neodymium magnets on the bottom of my locos to trip the contacts and they have enough 'reach' to close the reed switches down inside the ties.

View attachment 260119
3 amps is beefy for a reed switch, good choice in my opinion!