DCC a Hornby R070 TT?

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Bebbspoke
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DCC a Hornby R070 TT?

#1

Post by Bebbspoke » Sat Jul 25, 2020 6:19 pm

Hi Folks – newbie to this forum, not really a railway modeller but an electronics/sys dev eng who’s got cajoled into helping with 2 separate layouts.
Different owners & gauges 1 @00/HO & 1 @N. The 00/H0 is currently the full perimeter of a large semi, guesstimated upwards of a 1,000ft of track…
Construction was commenced ~ 45 years ago – ‘tis a most impressive layout. Old style – non DCC.
Sadly Old Father Time & Mr. Parkinson have taken their toll on the owner & a far smaller layout (with wheelchair access) is to be created in the garage.
It will be wired DCC using Digikeijs & TrainController Gold, such that it may also be fully remotely operated via pc…
Well there’s a brief intro – now here’s the problem… I wish to DCC an ancient Hornby R070 TT… I’ve various ideas… probably via Arduino & a stepper motor,
but please, has anybody succeeded in doing similar? – I expect rework to the TT drive should be relatively easy & the stepper control comparatively so…
… but how might I link such in via the Digikeijs & TCG??? Looking forward to your comments & suggestions, Cheers, Bebbspoke (aka John).

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Rog (RJ)
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Re: DCC a Hornby R070 TT?

#2

Post by Rog (RJ) » Sat Jul 25, 2020 7:39 pm

You will be better off starting with a different turntable if you intend to use arduino or stepper motors. The Geneva drive mechanism of the Hornby turntable doesn't lend itself to easy modification.

The Peco turntable, a kit you have to build, would probably be the least expensive alternative. Motorising kits are available.

There is a very similar thread on the Hornby forum, funnily enough! :D

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RAF96
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Re: DCC a Hornby R070 TT?

#3

Post by RAF96 » Mon Jul 27, 2020 9:38 am

There is plenty on the Hornby forum about converting their TT to DCC both the official way and the members better way, but as Rog says these use a DC motor driving a Geneva mechanism, essentially run until the latch drops into a detent and stop, repeat to the next outlet track location. Progression can be in either direction, one track at a time.

A Peco TT can be motorised and there are several simple and more complex kits available for the purpose, including stepper motors and Arduino. I believe RM Web forum has a detailed thread on the topic.

There are more sophisticated and expensive TTs available depending upon ‘your’ budget.

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yelrow
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Re: DCC a Hornby R070 TT?

#4

Post by yelrow » Mon Jul 27, 2020 1:57 pm

i went into this , some years ago, and found the best, (to my mind), and the cheapest to be a Frateschi, turntable. Simple conversion.

Chris
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Re: DCC a Hornby R070 TT?

#5

Post by Chris » Wed Jul 29, 2020 10:18 pm

For the motor control if you can do it so that every track is equally spaced then it will be much easier as you can rely on the accuracy of the stepper simply to move 'x' steps without any need to fit feed back for alignment.

for connecting the Arduino to the DCC one option
use a standard loco decoder, and use the two of the function outputs to pulse two inputs move CW, move CCW. it will still need some form of buffer to isolate the higher voltage.

an other option is to use a dedicated accessory decoder. the Hornby unit can be programmed that when an channel is activated it can be constantly on/pulse/ multiple pulses and even the pulse length can be set which may make it easier to set up.

will be interesting to see how you get on, im currently trying to make a stepper control a transverser but my basic programming isn't going well.

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RAF96
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Re: DCC a Hornby R070 TT?

#6

Post by RAF96 » Fri Jul 31, 2020 8:59 am

Rev 2.0 version of the Hornby R8247 Point and Accessory Decoder (PAD) can be set to a mode that allows defining the number of pulses as well as the length of the pulse, which should let you use an opto-isolator to protect an Arduino from the higher 12-14v DC output from the PAD.

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