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CV 29 question relating to:

1391 Views 7 Replies 6 Participants Last post by  zmil

Can you help please? I normally set CV 29 to have analogue and DC at 0 (which of course is off) Is this the correct thing to do and does it relate to non DCC only?


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Hi Charley

It's personal choice really. If you don't intend to run on DC then by all means switch it off.
I personally leave DC ON so that I can run on an oval of KATO track using a Gaugemaster DC controller when servicing etc.
Bit 2 does only refer to having DC enabling either ON or OFF.

Hi Charley

Another reason for switching off running on analog is to use the "Brake on DC" feature most decoders have.
This enables a Locomotive to slow down (at the deceleration rate set in the decoder) to a stop when entering a special section of track (isolated from the rest of the track) BitSwitch do some controls for automated stopping and starting
you can find details here


Personal preference but switching DC mode off is a good idea. It can help prevent runaways which was prevalent in some decoders. If going to run on DC it is not hard to turn it back on.

Ian sa
When the loco enters a brake on DC section and assuming the section is an isolated section of track set for DC what happens to the loco? By that I mean at what voltage should the section of DC be set for or does it not matter? Does the section need to be as long as the stopping distance of the particular motor? Once it has slowed down do you need to trun the track section back to DCC to initiate a commencement back to speed? Does the loco buzz when DCC fitted on a DC track like a Non fitted loco does on DCC?

so many questions

The Isolated section has to allow the full train to stop (at the decoders braking distance ) Wiggy has this setup on his Thomas N layout , I'm sure it is his post

-So Full train + Braking distance . It is still under DCC control but it has stopped until it gets a command to resume normal speed (Dc generator off) will the accelerate to set speed again

The DC is generated by a circuit (US$25)
You also need a Reed switch or similar to detect the Loco before it reaches the braking point in the Isolated section

No buzzing


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***Hi Paul

The braking section must be within 1 volt of the DCC section - Outxide that it may not work well. That usually simply means using the DCC as the source and just switching in a bridge rectifier via a relay. The loco slows and stops depending on settings in CV 3/4 so the section needs to be long enough for that slow down and stop time. There is NO need for any special circuit at all. What should happen is that the whole loco needs to be in the section when switched.

I have twice attached images showing how to do this - You need to have TWO sections that will switch to DC - with the first one being quite short and the second one being the one which triggers the DC change in both. That way guarantees the whole of the loco is in section.

No the loco with a chip will not buzz on DC UNLESS the controller is a lower frequency DC type which the decoder doesn't like, in which case it will run less smoothly than it would on pure DC.

Hi All

A more detailed explanation plus a video and a few diagrams are in this post Here

I hope this helps


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