BDL-168 grief

[John]

So, I started replacing my old BOD-H detectors from RRCkts with a BDL168, which is 16 detectors on one board .. everything has gone along really fine, until I got to installing detection on the two mains in front of the "wheeling" yard ..  The detector would indicate occupied on both tracks - even if the train wasn't there ..

I ohmed it all out - no shorts .. divided the block in to smaller sections - the problem went away .. connected the sections back, the problem came back with the last section .. hmmm .. wires ok - nothing crossed .. WTF? .. two days of troubleshooting - it dawns on me, this section of the layout got wet with liquid detergent several months ago .. it had soaked into the ballast - and never dried .. so it appears there is just enough resistance between the rails to trip the detector, but let trains run ..

Off to Kleins this weekend to get some flex, and replace the wet section with new track and ballast .. good grief ..

[Philip H]

John,
Educate a neophyte - how does this detector actually work?  DO you need some sort of resistor on the rolling stock?

[John]

This detector,  operates by detecting a resistance threshold across + / -   (Martin - jump in here if I screw this up)

Basically, your loco will provide enough resistance through the motor ..  somewhere around 25K Ohms

A lot of people will add resistors on wheelsets (you only need one axle per car) to ensure that the detection section works even after the loco moves to the next block .. if you use a caboose, thats the best place .. if you have cars with EOT, then thats where I would put it ..

make sense?

[Philip H]

Makes sense.  Thanks

[Bob Bufkin]

This the beginning of a signaling system?

[Ian MacMillan]

I sometimes had issues on the old layout when I would boot up the layout several blocks would show occupied. I would have to use Loconet-Checker to clear all the boards and then go from there.

[John]

This the beginning of a signaling system?

Yes .. you need detection to make it work properly .. unless you keep every signal red, then make the crew call the DS to get permission by the signal .. 

[Bob Bufkin]

You gonna use B&O position signals or got to the newer "nun" type signals?