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More on DCC and detectors

If any of the below seems to indicate that I have no idea of what I am talking about, that is probably true. I have a lot of research to go before I settle on a particular DCC manufacturer. But the planning for the layout can go on at full speed.

I see references to the fact (I think) that a current ocupancy detector cannot be used with DCC. I don't understand why. As I understand it, DCC is a lot like a vastly newer CTC16 where a digital control voltage is applied to the track. Unlike the old system where a steady voltage was available for power and the control signal rode on top, apparently DCC has a control signal that is powerful enough to do both.

So, obviously, if there is no motor, electronics, or resistance on the track there is no current draw and if an engine is available, there is. Why would it not work - or will it?

Thanks KRF

Reply to
KRF
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One of the big issues is common rail wiring. This is not a problem with DCC as long as you have only one booster. A second booster must be electrically isolated(double gaps). A lot if signal systems make use of a common rail return......

Jim Bernier

KRF wrote:

Reply to
Jim Bernier

A current detector will work on DCC. There are _some_ current detectors that will not work on DC; transformer coupled current detectors for example.

Reply to
KTØT

That reminds me that todays detectors should have a method of isolating the detector output from the track. This can be an opto-isolator or a relay.

Makes things a lat simpler.

Howard

Reply to
Howard R Garner

oooh not so fast.... Here is a transformer coupled DCC detector:

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You were right with the first part. Some occupancy detectors designed for DC circuits will work with DCC, some won't. It's possible to design circuit that works with both, but usually designers optimize for one or the other.

See also:

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Dave.

Reply to
Dave Mitton

The boards I built for the Canyon Mountain Ngineers (or whatever it's called) layout use that method. The detector (basically a modified Twin-T) is powered by the track power, the output is optically coupled into the main part of the signal board, which has it's own power supply. Were still at the point of using one booster, but I don't anticipate any problems when we add a second due to the isolation.

Reply to
Robert Reimiller

North Coast Engineering has a detector that uses impedence to detect. One of the power feeds is wrapped through the hole in the top of a little coil that looks like a tombstone. One can adjust sensitivity by inceasing or decreasing the number of times the power feed is wrapped through the hole. There is no physical connection between rail and signalling power.

I'd also suggest strongly looking at the line of signals, detectors and logic circuits available from Integrated Signal Systems. I've used their products since the mid 1990's with both DCC and earlier command control, and I am very happy with them.

rs

Reply to
Rick Stern

There was a site on the homemade pulse transformer detectors posted here. It used a 555 I think. Could someone please repost it. Thank you.

Reply to
Jon Miller

"Jon Miller" wrote in message news: snipped-for-privacy@corp.supernews.com... : There was a site on the homemade pulse transformer detectors posted : here. It used a 555 I think. Could someone please repost it. Thank you. :

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Just a reminder, as I have said, There are _some_ current detectors that will not work on DC; transformer coupled current detectors for example.

Reply to
KTØT

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