Skip to main content

Replies sorted oldest to newest

Thanks. I was just wondering what the characteristic impedance of O gauge track would be. Of course there are all sorts of issues with calculating this...and probably doesn't matter that much. It's probably just that one has some kind of load...like a bulb.

What is the "filter" that doesn't cause heat like a bulb?

On our layout the 24v blubs degraded the strength of the DCS control signal.  It went down from 9-10 to 4-5 in most instances.  But it wasn't as bad as the now discontinued OGR "Magic Bulbs" which dropped the signal to 0-1 ...

I use the ones I have left as a "current on" indicator powered by a transformer which does not connect to anything else.  That works okay ...

Originally Posted by cjack:

What exactly is the issue with DCS in this regard. Is this a transmission line reflection issue and the "filters" or bulb loads help to terminate the "transmission line" or track?

Originally Posted by cjack:

Thanks. I was just wondering what the characteristic impedance of O gauge track would be. Of course there are all sorts of issues with calculating this...and probably doesn't matter that much. It's probably just that one has some kind of load...like a bulb.

What is the "filter" that doesn't cause heat like a bulb?

I believe Susan Deets son did some measuring, calculating and came up with an optimal set of capacitors, resistors and maybe an inductor values that "tamed the wild beast".  Sure she will chime in.

 

I also believe it was Marty Fitzhenery (sp?) who discovered this trick when he was beta testing the prototype TIU before it was sprung on the public

Originally Posted by cjack:

Thanks. I was just wondering what the characteristic impedance of O gauge track would be. Of course there are all sorts of issues with calculating this...and probably doesn't matter that much. It's probably just that one has some kind of load...like a bulb.

What is the "filter" that doesn't cause heat like a bulb?

Don't have a clue what the characteristic impedance of the track would be, and I'm guessing it would vary wildly with different layouts and different rolling stock mixes.  The unterminated ends of sidings seem to cause the most issues, which is why they were were the bulbs or filters were being placed.

It got the moniker of Filter because that's the name the person building and testing them hung on them. But they are a Transmission line Termination in operation.

 

Note that many of them are not installed at the end of the track block, but at the power drop to the block (Modular layouts). They then serve to reduce reflections back onto the distribution net of the Power/DCS signal.

 

I really don't care what it's called, Just like the fact it works, and uses VERY little power to boot.

Post

OGR Publishing, Inc., 1310 Eastside Centre Ct, Ste 6, Mountain Home, AR 72653
800-980-OGRR (6477)
www.ogaugerr.com

×
×
×
×
Link copied to your clipboard.
×
×