Resistor wheelsets for detection ( what resistance to use?)

[lmackattack]

Im a little confused with what resistance value I should use for wheel sets

My club layout is using the team Digital Block D8 detection device. It simply passes one of the buss leads from the command station/ through the device /and then to the track. It detects current flow. It is also adjustable to set how sensitive it triggers.

Right now I just want to install wheel sets to all my cabooses to aid in detection. I would like a resistor that will give a solid trigger from one car. I plan to install 2 wheel sets per caboose.

thanks for any help

 

[fcwilt]

Hi,

I use RR-CirKits WatchMan for my occupancy detection.

They work fine with 10K wheel sets.

Frederick

 

[lmackattack]

Yesterday We tried Jaybee wheelsets at 15k and that did not trigger. We then tested 10k resistors and it was still not a reliable trigger. I had some resistors laying around and it seams 4.7k was a solid trigger. is this to low of a value? Im worried about power loss but I do also have plenty of boosters to support the layout.

 

[fcwilt]

Hi,

With two 10K wheel sets per car then most of the time you will have 5K across the rails - which should work.

Frederick

 

[crusader27529]

Hi,

With two 10K wheel sets per car then most of the time you will have 5K across the rails - which should work.

Frederick

The reason he's using 2 resistors is so that EITHER wheel with the resistor will be detected, NOT to need BOTH wheels in contact for detection. That would make detection unreliable......

With 2 trucks that have resistors, it's more reliable, AND if the caboose is straddling a block, BOTH blocks will show as detected.

 

[fcwilt]

The reason he's using 2 resistors is so that EITHER wheel with the resistor will be detected, NOT to need BOTH wheels in contact for detection. That would make detection unreliable......

With 2 trucks that have resistors, it's more reliable, AND if the caboose is straddling a block, BOTH blocks will show as detected.

True which is why I said "most of the time" - perhaps I should have said just "often".

 

[lmackattack]

I started with 10K resistors on 2 wheels but that was not giving solid detection. I was also having issues with these 10K on plastic axles. the "wire paint" just does not do as good as a job as some have claimed. As soon as I tried the 4.7K on one metal axle the detection was triggered reliably.

I think I will now only use 4.7K resistors on full metal axles. I just hope that the power drop will not be a issue. ?

 

[fcwilt]

...the "wire paint" just does not do as good as a job as some have claimed.

What type of "paint" were you using - the silver bearing kind?

The kind I use is expensive - retail of $50 for 20 grams - but it works.

I have used it for all of my wheel sets and the resistance measurement has always been within the expected range of values.

Since I am using electromagnetic uncouplers I have to use non-magnetic wheel sets. The ones I use (Kadee) have plastic axles.

Frederick

 

[lmackattack]

What type of "paint" were you using - the silver bearing kind?

The kind I use is expensive - retail of $50 for 20 grams - but it works.

I have used it for all of my wheel sets and the resistance measurement has always been within the expected range of values.

Since I am using electromagnetic uncouplers I have to use non-magnetic wheel sets. The ones I use (Kadee) have plastic axles.

Frederick

I was using something found on Ebay "wire glue". I think its just graphite?

what is the name of the stuff you are using? I have lots of cars with metal wheels but Plastic axles...

 

[fcwilt]

I was using something found on Ebay "wire glue". I think its just graphite?

what is the name of the stuff you are using? I have lots of cars with metal wheels but Plastic axles...

[h=1]MG Chemicals 842 Silver Print Conductive Liquid Paint, 20g Container[/h]
I got mine on Amazon.

There is also a cheaper product:

[h=1]MG Chemicals 840 Nickel Print Liquid Paint, 20g Container[/h]
but I have no idea if it would work.

Frederick