# Solutions for auto acceleration in my Point to Point setup?



## theinteresthunter (Jan 30, 2016)

I'm building my first railroad set which will be an accent piece in my house. I'm looking for recommendations to accomplish my goals. Since what I'm going for is not a simple trolley stop/start out-of-the-box system, I'm looking for guidance from you technical gurus. See below. Thanks! (Also, included here is an image of my railroad goals, illustrated.)

MY RAILROAD GOALS:
1. Point to Point
2. Pauses at each point for a value I set.
3. Accelerates at a slow rate (a value I set) from stop.
4. Reaches a top speed that I set (which will be fairly slow).
5. Begins to decelerate at a point that I choose. *(Most likely the halfway point.)
6. Comes to a smooth stop at the other point.
7. Repeat from step 3.
8. After setting up the train’s performance, the operation is hands-free.

This train, going soothingly back and forth, will be a feature in my house similar to how a lava lamp sits there and does its thing.

WHAT I UNDERSTAND I NEED
1. An engine, cars, and a track.
2. DCC or DC controller and compatible power supply.
2b. If DCC, one decoder to put on the engine.
3. Sensors of some sort (compatible with the controller) to detect the train and trigger an action from the controller (like accelerate/decelerate/stop/start).

WHAT I DON’T UNDERSTAND
1. Which system will achieve my railroad goals (above).
2. How to make the train’s performance automated – hands-free.

MY SKILLS
1. Woodworking
2. Light coding/programming
3. Electrical (soldering, multimeter)


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## gregc (Apr 25, 2015)

theinteresthunter said:


> I'm building my first railroad set which will be an accent piece in my house.


this sounds ambitious.

one approach to control speed using DC is to divide the track into many blocks with either resistors or other means to control track voltage for the desired speed on that block.

station stops would probably need to be triggered by a detector (i.e. optical) and using a timer mechanism to break power to the layout for some specified time.

a similar timing mechanism at the end stations would also reverse polarity of the track voltage. After the timeout-period track power is restored with reverse polarity and operation repeats in the reverse direction. Rob Paisley has auto reversing circuit boards. He may other circuits you need.

555 timers could be used for timing. either a mechanical or electronic relay used to cut power and either an electronic or mechanical double-poll double-throw (DPDT) relay used to reverse polarity.

A DCC approach is certainly possible. I think it would also require station detectors. It could do a better job at controlling speed but would require a more sophisticated system to control DCC commands to the track.


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## RT_Coker (Dec 6, 2012)

Open-Source DBTC can do this type of automation with strait DC power on the track, one-DBTC-decoder (~$10 more than DCC-decoder). But (and a big one), there are no DBTC-decoders yet and there may never be.

Somebody is doing the same type thing with DCC++. Look here: http://www.trainboard.com/highball/index.php?threads/dcc-hardware-throttles.90315/#post-961597.
Bob


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## martink (Oct 30, 2015)

You mention that you can cope with basic programming - if so, this sort of thing is fairly easy to do with an Arduino or any other simple microcontroller. 

You need some basic PWM motor drive hardware and four detectors - preferably IR or LDR/photocell detectors, but you could do it with magnets and reed switches. Two of the sensors would be stop sensors at the end of the track, the other two would be set some distance back and act as slowdown warnings. You would also want two potentiometers tied to analog inputs to select two speeds: fast and slow.

The software would set the direction, slowly ramp up the PWM to the higher speed and ignore the first two sensors. When the far slow sensor is passed, gradually slow to the lower speed and then crawl along till you reach the stop sensor. Stop dead, pause, repeat.

I did much the same thing on my little T gauge layout, but set it up as a three train tail-chaser instead of a reversing shuttle.

Alas, I am not aware of any commercial products that will give you the acceleration and deceleration feature, but there are a number out there that can handle the basic full-speed/dead-stop shuttle, with optional variations such as intermediate stops, two trains and passing loops, etc. One such example is www.heathcote-electronics.co.uk


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