Reliability of LGB Track Contacts 17100 or Reed Switches and Best Practice for Use and Installation

[fairflixt]

a varistor (VARiable resiSTOR) can vary the current in such a way as to slow down peaks of current, i.e. help absorb the energy that might otherwise pit the contacts

Aha, so it is about protecting the reed switch itself and presumably increasing it's lifespan.

 

[fairflixt]

Here's a link to a discussion on this forum on the varistor from a couple years ago that I just came across. Some familiar faces in that thread. As for finding a specific part - it looks like if you set the max voltage to 25V, then the typical varistor on Digi-Key seems to have a peak current of 100A for one surge and 50A for two surges which would roughly be in line with the description in the image I posted earlier. Lots of options in that range.

 

[fairflixt]

Some additional really good info from The Shed (thanks!) in this thread here as well as a few comments further down.

 

[Greg Elmassian]

I might take exception to the use of schottky diodes... I think the faster recovery time is better, agreed, but the lower resistance allows more current to flow, not better, worse.

This is splitting hairs though, since the addition of a varistor is the key to helping handle high voltage/current spikes that are trying to kill the reed switch.

Greg