Hornby turntable worries - a beginner

[2e0dtoeric]

If - when the points are directed away from the t/table, the t/table track is dead - where are you going to get the power from to drive loco's on or off it?

The t/table track power is taken from the first entry, with the little brass connector 'fingers' to the stubby straight.

Next problem - if you happen to have rotated the t/table 180', then you have created a reverse connection = dead short!

If you search the various threads on here, you will find page after page of 'how-to' stuff.

[RB51]

I am waittng for a Hornby 070 turntable to operate on DCC and wondering how to wire it up without any alterations to turntable – looked at all the methods and am a bit concerned. I don't want to be involved in  any "butchery" !!

Will the following work -simplest I can think of 

Track to turntable from main track is only live when points are directed this way – when set to main track the turnout to turntable will be dead.

  The turntable motor runs off DC controller or DCC chip on motor if prefered so independent of the following.

1. Select loco to send to turntable

2. Set points from main track to turnout to turntable

3. Drive loco onto turntable

4. Set Hornby points back to main track to isolate turnout to turntable

5. Use turntable motor to swing bridge to sidings required-track not live therefore no shorting.

6. Drive engine into sidings

7. Set points back to turnout for turntable

8. Move bridge back to entry track again or sidings required

9. Go To 3 or finish

 

 

[geoffsy]

If - when the points are directed away from the t/table, the t/table track is dead - where are you going to get the power from to drive loco's on or off it?

The t/table track power is taken from the first entry, with the little brass connector 'fingers' to the stubby straight.

Next problem - if you happen to have rotated the t/table 180', then you have created a reverse connection = dead short!

If you search the various threads on here, you will find page after page of 'how-to' stuff.

You drive the loco on to the turn table whilst the points are directed to the turn table - you then turn off the power to the rails of the bridge by changing the points back to mainline. The bridge is now dead hence no shorts no matter how much you turn the bridge, turn the brige and then restore power to bridge by changing points back to direction of turntable

[Chrissaf]

Please try and avoid using the 'white arrow, blue box' button. This is not a 'Reply to this Post' button. Write your reply in the empty ' Reply to "named post" ' box at the bottom of the page and click the Green 'Reply' button.

.

-------------------------------------------------------------------------------------------------------------

.

Actually, just had a bit of a re-think on this. The Hornby TT uses a 'Split Ring', it is TT brands with a 'Slip Ring' design that give a short circuit at the 180 degree position.

.

The Hornby TT 'Split Ring' reverses the bridge track polarity as it turns past the half way point. It is the opposing rails touching as it turns that generate the DCC short circuits.

.

Thus, after thinking through your proposal in a little bit more depth, then it may work. It is however a lot of faffing about for a DCC layout where it is expected to always have live track power. The suggested modification is simple to implement at the building stage and gives the big advantage that locos with lights and/or sound will continue to display those features (except where the rotation of the bridge crosses over the gap in the 'Split Ring' where the track polarity is reversed).

[Chrissaf]

The Hornby TT is designed for Analogue DC track. Using it on DCC track is going to involve some form of modification. It doesn't have to be the butchery that the Hornby modification method describes.

.

Check out this previous thread (just in case this has NOT been part of your previous reading list), it contains the wisdom of much thought on the subject by forum members as to the most effective way of modifying the Hornby TT for DCC use.

.

https://www.hornby.com/uk-en/forum/r070-hornby-turn-table-to-dcc-including-images/?p=1

.

Using a loco decoder to turn the TT is optional, you can still use analogue DC for that purpose and just focus on the track power modifications for DCC.

[Fishmanoz]

Chris, I agree Geoff’s method will work, even on the reverse polarity outlets as, when there is power applied from only one direction and not when the bridge is rotating ,there can’t be any shorts.  However, one day he will forget to change the point and shut his layout down with a short circuit overload. Hopefully that will not cause any decoder damage or cause too many to revert to default settings.  And given this likelihood, fitting bus terminators should be considered mandatory.  Given the apparent lack of a separate bus, I’d do this across the track near the TT.

 

Then I also agree with Chris that this is not an elegant DCC solution. Personally, I’d use the gapped inlet track method first invented by blackbird.  Geoff’s setup is ideal for this method given power is only coming from the one direction so no mods beyond the inlet gapping will be needed.  And the TT isn’t butchered. Then we know there are a range of ways which all have their following. 

[96RAF]

My TT wiring method (regardless of TT manufacturer) is to the wire the inlet road in parallel to all the outlet roads. The only polarity that changes is the TT bridge. Mine is done manually by way of a DPDT centre Off switch but this can be an RLM or any other method that allows the bridge to swap polarity.

I drive on and swing the bridge up to 180 degrees and off again, but if the bridge needs to go 180 degrees or over then a bridge polarity swap brings it back into synch again.

 

Apply this simple logic to the Hornby TT and you can see where any modification or isolation needs to be and when.

Rob

[geoffsy]

from Geoffsy ; re timetable worries.

Received my turntable today - a replacement as first didn't work properly.

Unwrapped and tested the new one - once again stop and start with the brass contacts rubbing against the outlet tracks and causing the gears to jam so took out the brass contacts and will use one of the well tried methods - favour the rotary switch - thanks to all for help

Geoffsy

[Nictor]

I simply bought the Bachmann EZ track one. More expensive but ultra easy to DCC. Took me all of three minutes to unscrew a cover, plug a chip into the DCC socket and then set it up to a loco address number. Bit noisy but works great.