auto stopping at stations

Basic electrical and electronics, such as DC/Analog control.
steamerorb
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auto stopping at stations

Postby steamerorb » Wed Nov 10, 2021 10:19 pm

hello everyone, I'm just starting a new model railway in 009 which I'm hoping to have four stations, what I want it to do is when a train gets to a station I want it to slow down and stop automatically, it doesn't have to be very precise as to where it stops but I want to be able to set a couple of trains running and then let them get to the next station, restarting them will be completely manual so cutting out the device to slow them at a flick of a switch. the layout will be dc analogy. I could get them to stop suddenly just by having an isolated section and will probably include one to stop possible overruns but I want it the train to slow first, over three to four inches is enough as the speed will be low anyway, does anyone have a circuit diagram that could achieve this or a commercial device that would?

rob

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Re: auto stopping at stations

Postby b308 » Thu Nov 11, 2021 7:32 am

https://heathcote-electronics.co.uk/sta ... SA8-S.html

There are others available, search "auto stop model railway" and you'll find them. Never tried them so don't know how well they work.

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Bufferstop
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Re: auto stopping at stations

Postby Bufferstop » Thu Nov 11, 2021 9:54 am

I've got their auto reverse module which gives a dwell time at each end of a point to point. Nothing complicated, it just reverses every so many seconds. If you make the reversal period longer than the time to travel from one end to the other, then it waits at the end until the module switches. The biggest downside to it is you need to put an insulating gap in one rail at each end and put a diode across the gap. I doubt that the station stop module is much different.
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Re: auto stopping at stations

Postby Flashbang » Thu Nov 11, 2021 10:23 am

The Heathcote Electronics station stop module along with two IRDOT detectors works well and I had one installed on a former club layout.

The Block signalling SSM1 station stop module is complete with sensors and needs just a separate power supply (plus the DC controller) connecting It doesn't use cuts in the rails or IRJs etc. http://www.blocksignalling.co.uk/index.php/station-stop-module-ssm-1
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steamerorb
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Re: auto stopping at stations

Postby steamerorb » Fri Nov 12, 2021 7:14 pm

thanks for the reply's folks, what you're suggesting looks good but is expensive for what it is as it has lots of functions I don't need like dwell time, revering and restarting; I just need a soft stop, everything else is manual, it doesn't need to be the same with different locos, just a loss of power to them as they travel the last couple of inches in the station. I did think about doing it with resistors and several small sections before am isolated section but that would be jerky, I think that just having a capacitor wired in somehow (it's a long time since I learned about electronics and I wasn't much good back then) would be enough

rob

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RAF96
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Re: auto stopping at stations

Postby RAF96 » Sat Nov 13, 2021 10:04 am

It can be easily done in DCC with a decoder that works with asymmetric DCC, a Lenz idea that uses a gap in the rails with a five diode BM1 across the gap. The diode module creates a pseudo DC voltage bias that the decoder reacts to and slows the loco to a stop. Restarting is by way of a ‘signal’ being set i.e a simple switch in parallel to by-pass the module and the loco departs.
A similar thing could be made by fitting a single diode across a gap in the rails at your station, again with a manual by-pass switch, similar to the GM SS1 reversing shuttle method.
I have seen DC trams made to auto-shuffle from stop to stop using the rail gap method. As one tram arrives it triggers the standing tram to depart. Here is the link http://www.gordonstrams.net/ATSpage0.htm
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Flashbang
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Re: auto stopping at stations

Postby Flashbang » Sat Nov 13, 2021 11:17 am

As the layout is DC (Analogue) operated you will need, and as you specify, a means of slowing the loco/train to a halt not just stopping it suddenly which is what the loss of DC beyond an IRJ would cause - Loco skidding to a halt! To slow a loco to a stop will need some electronics to turn down the rail power slowly and some means of knowing when this has to be undertaken. Hence the need for a control module and some form of train detection - Infra red in the cases above, but could be a reed switch and all locos fitted with magnets.
As I read it, you also want to start the stopped loco when one of two options are meet. A) When the section ahead is clear of its train, or B) by operating a by pass switch. Both are achievable, but again the controlling section module needs some form of electronics to start to increase the rail volts to allow a smooth pull away when the command to move off is received. A second control module would be needed at the next section too and so on.
All the above has to come at a cost! :o To design, build and test slow down/start off automatic control modules is not cheap, hence the retail costs you're seeing.
An option to consider is the possible use of Arduinos and suitable shields (Cheap Chinese clone ones?) a suitable Arduino sketch and some circuitry??
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Teedoubleudee
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Re: auto stopping at stations

Postby Teedoubleudee » Sat Nov 13, 2021 12:47 pm

I use a Picaxe micro processor to send a variable logic level output to a cheap pwm motor controller. It's triggered from a track mounted reed switch.

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Albert
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Re: auto stopping at stations

Postby Albert » Sat Nov 27, 2021 11:47 am

steamerorb wrote: I just need a soft stop, everything else is manual, it doesn't need to be the same with different locos, just a loss of power to them as they travel the last couple of inches in the station.... I think that just having a capacitor wired in somehow (it's a long time since I learned about electronics and I wasn't much good back then) would be enough
rob

I've been thinking abut something similar and the capacitor sounds like a good idea. I'll try to find time for a play and report back.
Albert

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Roger (RJ)
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Re: auto stopping at stations

Postby Roger (RJ) » Sat Nov 27, 2021 1:35 pm

Albert wrote:
steamerorb wrote: I just need a soft stop, everything else is manual, it doesn't need to be the same with different locos, just a loss of power to them as they travel the last couple of inches in the station.... I think that just having a capacitor wired in somehow (it's a long time since I learned about electronics and I wasn't much good back then) would be enough
rob

I've been thinking abut something similar and the capacitor sounds like a good idea. I'll try to find time for a play and report back.

Remember that electrolytic capacitors don't like reverse polarity and will go BANG

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Albert
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Re: auto stopping at stations

Postby Albert » Sun Nov 28, 2021 10:02 am

Roger (RJ) wrote:
Albert wrote:I've been thinking abut something similar and the capacitor sounds like a good idea. I'll try to find time for a play and report back.

Remember that electrolytic capacitors don't like reverse polarity and will go BANG

True. I'm assuming that the stretch of track in question will be permanently one way, although a diode to protect the capacitor would probably be a good idea, just n case...
Albert

steamerorb
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Re: auto stopping at stations

Postby steamerorb » Wed Dec 01, 2021 2:53 pm

thanks for the replies and idea, no auto restart is needed and it'll only be in one direction per section of track, any trains going over that section in the opposite direction or starting away would have to have the manual override engaged so an electrolytic capacitor with diode could be used

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Flashbang
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Re: auto stopping at stations

Postby Flashbang » Wed Dec 01, 2021 7:18 pm

I think on DC you would need a very large value capacitor and suitable series resistor of a high wattage and resistance to reduce discharge time. This question has arrived many times in the past with DC operation, and IMO I feel electronically controlled slow down and restart is the only real option! :o
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Re: auto stopping at stations

Postby Bigmet » Thu Dec 02, 2021 11:06 am

steamerorb wrote:... I want the train to slow first, over three to four inches is enough as the speed will be low anyway, does anyone have a circuit diagram that could achieve this or a commercial device that would?...

The readily available commercial devices are in the DCC package; and really you should consider it, because you get so much more.

One of the fundamental DCC advantages over DC is that the track power is permanently full on. This makes a real difference to lightweight traction, which is always compromised for pick up due to low contact pressure, and especially so when the necessary small DC current for low speed movement is applied.

Then there is the ability to 'tune' the motor output of the decoder to optimise performance of each loco, compared to having to use a fixed value device on DC, which may not operate all the mechanisms equally well for the effect you want.

And plenty more

Yes, it costs. But buy a good system and look after it, and that will serve you many years. (I am approaching 20 years in with DCC, still using the system and decoders purchased at the start, all performing as beautifully as ever. 'Quality is remembered long after the price is forgotten.')

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Bufferstop
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Re: auto stopping at stations

Postby Bufferstop » Thu Dec 02, 2021 11:36 am

RAF96 wrote:It can be easily done in DCC with a decoder that works with asymmetric DCC, a Lenz idea that uses a gap in the rails with a five diode BM1 across the gap. The diode module creates a pseudo DC voltage bias that the decoder reacts to and slows the loco to a stop. Restarting is by way of a ‘signal’ being set i.e a simple switch in parallel to by-pass the module and the loco departs.
A similar thing could be made by fitting a single diode across a gap in the rails at your station, again with a manual by-pass switch, similar to the GM SS1 reversing shuttle method.
I have seen DC trams made to auto-shuffle from stop to stop using the rail gap method. As one tram arrives it triggers the standing tram to depart. Here is the link http://www.gordonstrams.net/ATSpage0.htm


The tram layout on which I saw this working was quite simple, a dead section in the return rail stopped the first tram arriving, the following trams wheels bridged the gap at one end and made the waiting tram move. If it's wheels bridged the out going gap before the arriving tram was fully in the dead section they both kept moving until neither was bridging a gap. Occasionally one of the trams had a different wheelbase or one wheel not picking up. The first tram wouldn't move, the second would then shunt it forward, then it might start, or they would both remain stationary until a third tram arrived shoving both forward until one or more got going. Not quite prototype behaviour but it didn't look much different to the pack them all in antics which happened at many tram (and trolleybus) stops.
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