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Marklin turntable project - Remote control
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Offline ixldoc  
#1 Posted : 19 February 2016 01:34:39(UTC)
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ixldoc

Australia   
Joined: 18/11/2015(UTC)
Posts: 220
Location: Brisbane,Australia
Hi all,
Following up on my transfer table project, I would like to demonstrate my wireless adaptation of the Marklin turntable. I designed and built this a few years ago well before digital control was available. I wanted to avoid using the slightly clumsy control switch which came with the turntable.
It uses the principle of IR LED emission and phototransistor detection as used later in my transfer table. The remote control simply selects the phototransistor associated with the desired track. The remote is twelve channel but eight would have been sufficient for me as I only have six tracks entering the turntable. Buttons 1-6 are track selection, 11 is counterclockwise and 12 clockwise rotation.
Basically I built an interface with the turntable and did not alter any wiring under the bridge that could be required for a return to normal operation.
Some photos :
Turntable 5.jpgTurntable 2.jpgTurntable 3.jpgTurntable 4.jpgTurntable 1.jpgTurntable 6.jpg

The LEDs are red which change to green when a track is selected and the blue LEDs at each end indicate direction of travel.
A short video :


Thanks for watching, regards,
Howard.
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Offline Chook  
#2 Posted : 19 February 2016 03:07:15(UTC)
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Chook

Australia   
Joined: 15/08/2012(UTC)
Posts: 234
Location: Perth, Western Australia.
Howard great project.
Can I ask what optics you used (part numbers)and why did you use 2 emitters on the turntable?

Regards.........Chook.
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Offline ixldoc  
#3 Posted : 19 February 2016 03:50:54(UTC)
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ixldoc

Australia   
Joined: 18/11/2015(UTC)
Posts: 220
Location: Brisbane,Australia
Hi Chook,
This project was completed in the late 1990's as I recall so my memory of events is a bit vague . I know I bench tested the setup with one 3mm IR LED but I had to push the current to close to it's maximum to get the phototransistor below to react. I am a great believer in over-engineering to avoid failure so I decided to use two LEDs in series and dropped the forward current a bit. I angled them to create a sweet spot if possible on the deck below so the phototransistor wouldn't react to IR scatter. It seemed to work.
My post yesterday re the transfer table relies on an IR LED embedded in a nylon block with a small hole and a slit to achieve something similar.

I found the data sheets which I thought would be history!
The IR LEDs were CQY58A and the recommended phototransistors were BPW22A.Both can handle 50Volts, the IR LED forward current max 50mA and the phototransistor current collector 25mA. Both rated 100mW. These are 3mm diameter components. The IR LED is dark blue infrared transparent epoxy and the PT is water clear.
My fear that the upward facing PTs would be affected by ambient light never materialised.
I have to admit waking at night in a sweat when I was designing it, having thought of other problems that might occur.
Regards,
Howard.
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Offline Chook  
#4 Posted : 20 February 2016 01:00:19(UTC)
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Chook

Australia   
Joined: 15/08/2012(UTC)
Posts: 234
Location: Perth, Western Australia.
Thanks Howard for your excellent reply.
I am currently predisposed in my other hobby - flying but keep an active eye on Marklin goings on. I will be building my own turntable and was extremely interested when you shared your experiences with both the turntable and transfer table.
Also as part of my project I will be experimenting with locating various components of the model like trains and turntable positions. Some time ago I spotted an infra red detector which forms part of the Arduino suite of add on modules. I have purchased about 15 of these modules from Hong Kong landed at my door for about $1 each Aussie which includes the PCB, infra red pair, sensitivity adjustment and amplifier. I couldn't design and put it together for that so it would seem to be a bargain.
I will share my findings with the forum when they become available.

Regards.........Chook.

ebay arduino detector pcb.JPG
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Offline ixldoc  
#5 Posted : 20 February 2016 04:33:24(UTC)
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ixldoc

Australia   
Joined: 18/11/2015(UTC)
Posts: 220
Location: Brisbane,Australia
Hello Chook,
I hope you don't mind if I post you some more info. I would love to build a scratch built turntable and maybe.....

A few words of wisdom learned by experimenting: The reflectance ones like yours and many of mine work well but not on a black surface. A friend has a show layout and we used one to detect the steam train coming onto a turntable bridge, but it would often simply fail to register unless the silver valve gear was in front of it. Beware of bright sunlight and incandescent lighting. Fluoro lights are fine. To get an accurate register and stop at a specific point ( to line tracks up for instance), you will probably need facing components and some sort of shielding of the phototransistor ( I used black felt pen and coloured all the dome of the PT except for the rounded tip.) As you will have power on the turntable bridge for the track, it is available to supply the IR LED, and have the PT on a fixed position to supply the power and take off the output.

I will take some photos and post soon.
Regards,
Howard.
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Offline ixldoc  
#6 Posted : 20 February 2016 05:00:39(UTC)
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ixldoc

Australia   
Joined: 18/11/2015(UTC)
Posts: 220
Location: Brisbane,Australia
Hi Chook,
Some photos of items I have used as promised. You may well have seen them. As you say why on earth try to make them when they are so cheap and small. How I wish I had them many years ago. A bit like regulated power supplies. I used to build kits from Dick Smith and Jaycar which were linear and got hot. Now I have adjustable switch mode units good for at least 1 amp and the size of my thumb nail.
Some photos:
DSCN0481.jpg
This toilet block contains the same unit as you posted, facing the track. Two holes allow the IR transmission and reflection.
DSCN0483.jpg
The two at the top are of great interest, the left because it is so small and works from 1mm to 4mm, the right one is very small, reliable, mounted on a board and available locally for about $8.
DSCN0487.jpgDSCN0490.jpg
DSCN0492.jpg
This one has one main board but IR pairs on long leads.
DSCN0493.jpg
This is handy for detecting a flat reflecting arm passing between the IR pair.
DSCN0495.jpgDSCN0496.jpg
I made these up in pairs back in the late eighties for a commercial Marklin train layout to avoid mechanical switch failures. They are not modulated in any way and simply line up across the track. One of the pair was made with some adjustment.
I like IR and it is great for train layouts.
Watch the connection to the phototransistor as I recall the short leg is the collector unlike a LED where the long leg is positive.
Regards,
Howard.
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Offline Chook  
#7 Posted : 20 February 2016 13:27:06(UTC)
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Chook

Australia   
Joined: 15/08/2012(UTC)
Posts: 234
Location: Perth, Western Australia.
In a forum with so many members it was only a matter of time before I discovered someone like yourself who appreciates the joy of manufacturing scratch built projects with an electronic theme.
I will at some stage start playing with these modules by hooking them up to the CRO and see exactly what noise is being generated to cause the false triggering.
Yes I was under no illusion that these units required various forms of shielding , especially with their simple circuitry.
I do a lot of radio work for fellow gyrocopter pilots ( you have a large nest of these guys in Brisbane) which predominantly deals with engine noise suppression over the comms avionics circuits. Generally these machines have in the order of 120 decibels just behind the pilots helmets so I am reasonably familiar with noise suppression.
However trying to re invent the wheel is not what I am about so any tips are welcomed. You have volunteered some great ones - Thankyou Howard.
Power supplies -you are probably well versed in an old favorite of mine - 2N3055 - ahh the heatsinks!





Regards........Chook.
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Offline PJMärklin  
#8 Posted : 21 February 2016 10:26:49(UTC)
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PJMärklin

Australia   
Joined: 04/12/2013(UTC)
Posts: 2,210
Location: Hobart, Australia
Originally Posted by: ixldoc Go to Quoted Post
Hi all,
Following up on my transfer table project,


Hello Howard,

I have enjoyed your posts.

What is the story behind this little piece of Hobart ? :


UserPostedImage


Regards,

PJ
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Offline ixldoc  
#9 Posted : 21 February 2016 12:53:35(UTC)
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ixldoc

Australia   
Joined: 18/11/2015(UTC)
Posts: 220
Location: Brisbane,Australia
Hi PJ,
Trust someone from Tassie to rat me out!
When I did the turntable project, I wanted something on my layout to depict the action taking place. It had to be round and guess what was handy, a sticker from the casino. It had a vaguely American railway sound to it, but I used it anyway.
Regards,
Howard.
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