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Offline ixldoc  
#1 Posted : 02 July 2016 05:59:35(UTC)
ixldoc

Australia   
Joined: 18/11/2015(UTC)
Posts: 219
Location: Brisbane,Australia
These gates were always a favourite of mine and they have been around for many years, a testament to a good design and sound manufacture.
My two issues were rapid speed of action due to solenoid actuation,and the fact that the solenoids had to be powered to hold the gates down. (250 mA or so.) When powered off, the booms simply returned to the upright position by virtue of the counterbalance weight.

I bought a set recently to have a look at with the idea of motorising them. Under the metal base the great quality of Marklin manufacturing was evident, everything well laid out, screwed not riveted and blued metal for the solenoid frame. A very easy job to remove the boom arms from above.

When the solenoids were removed which was simple, it was as if Marklin knew I wanted to mount motors to the frame because holes existed in the frame which lined up with the small geared motors I was to use. I had to drill a couple more to slip a small screwdriver through the frame to tighten the motor mount screws. The motors are 6Volt 30 RPM.

Next step was to make a small aluminium pulley wheel ( for both sides) and to cut a thin 2mm groove on the right hand side (facing along the boom) of the long brass gear which drives the arcuate gear on the boom shaft. I did both these on a lathe, using a thin flat diamond file to cut the groove in the brass gear. This did not harm the gear at all and it is still quite useable should I wish to return to solenoid drive. ( The arcuate gear meshes with the left side of the gear and the solenoid in the centre of the gear.) Marklin knew I wanted to use that gear! The drive from front pulley to brass gear is via a 10mm silicon O ring. The rear boom drive is via an 11mm ring to allow for a little slippage if needed. (The rear boom is set a fraction faster than the front to make sure it travels the full distance both ways.)

Two leaf switches were mounted under the metal base to arrest the booms at their limit of travel. A plunger was inserted in the support for the boom when down, and the other was actuated by the counter weight when it raised fully. I used the front boom switches to cancel both booms and made provision to synchronise the booms timing.

The motor control was 6 volts AC via two diodes per motor. This allows simple reversing of the motors via a SPDT switch and also drives the motors with half wave DC . This gives the motor 25 pulses per second and allows very low voltage yet still overcomes "stiction". I mounted the gates on a plinth as I couldn't use them on my layout. The switch would be best replaced on a layout with track detectors and a latching relay.
I added a flashing LED to each crossing sign and a light in the guard house as it was begging to be done!

After all this I made a Vero board circuit board under the plinth and wired it up. It all worked and then I realised I hadn't taken any photos ! Aaaargh! Sorry but I wasn't going to pull it apart.

Level xing 1.jpgLevel xing 2.jpgLevel xing 3.jpgLevel xing 4.jpgLevel xing 5.jpg

A short video


Thanks,
Howard.
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Offline Danlake  
#2 Posted : 02 July 2016 06:19:21(UTC)
Danlake

New Zealand   
Joined: 03/08/2011(UTC)
Posts: 1,551
Excellent Howard,

Very nice job - thanks for sharing!

Brgds Lasse
Digital 11m2 layout / C (M&K) tracks / Era IV / CS3 60226 / Train Controller Gold 9 with 4D sound. Mainly Danish and German Locomotives.
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Offline cookee_nz  
#3 Posted : 02 July 2016 09:05:27(UTC)
cookee_nz

New Zealand   
Joined: 31/12/2010(UTC)
Posts: 3,668
Location: Paremata, Wellington
Great job, can you add some photos of the actual finished mechanism ?

Cheers
Cookee
Wellington
NZ image
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Offline ixldoc  
#4 Posted : 02 July 2016 09:11:27(UTC)
ixldoc

Australia   
Joined: 18/11/2015(UTC)
Posts: 219
Location: Brisbane,Australia

Great job, can you add some photos of the actual finished mechanism ?

Hi Cookee,
I was not keen to pull it apart again but I will have a look.
Regards Howard.
Offline kimballthurlow  
#5 Posted : 02 July 2016 10:26:08(UTC)
kimballthurlow

Australia   
Joined: 18/03/2007(UTC)
Posts: 6,071
Location: Brisbane, Australia
Hi Howard,
Brilliant accessory, nicely done.

regards
Kimball
HO Scale - Märklin (ep III and VI, C Track, digital) - 2 rail (USA and Australia) - 3 rail (English Hornby Dublo) - a few old O gauge.
thanks 1 user liked this useful post by kimballthurlow
Offline ixldoc  
#6 Posted : 02 July 2016 10:36:22(UTC)
ixldoc

Australia   
Joined: 18/11/2015(UTC)
Posts: 219
Location: Brisbane,Australia
Hi again Cookee,
I nerved up and took it apart to this stage without disturbing any wiring.
Hope this helps to supplement the description.
Regards,
Howard.Level xing 6.jpgLevel xing 7.jpg
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Offline Minok  
#7 Posted : 06 July 2016 01:56:21(UTC)
Minok

United States   
Joined: 15/10/2006(UTC)
Posts: 2,218
Location: Washington, Pacific Northwest
Very cool! My first thought was to use a servo solution that can be digitally driven by a pulse width modulated signal (PWM), but this solution with a basic motor works great as well.
Toys of tin and wood rule!
---
My Layout Thread on marklin-users.net: InterCity 1-3-4
My YouTube Channel: https://www.youtube.com/user/Minok1217/
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Offline ixldoc  
#8 Posted : 06 July 2016 05:33:56(UTC)
ixldoc

Australia   
Joined: 18/11/2015(UTC)
Posts: 219
Location: Brisbane,Australia
Hi Thomas,
I ran a few ideas first using a geared stepper or a servo but the simplicity of the geared motor which sat perfectly under the baseplate won the day. Easy control and easy to apply track detectors in both directions.
Thanks for the comment.
Regards,
Howard.
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Offline Holz1  
#9 Posted : 17 May 2021 11:27:00(UTC)
Holz1

Netherlands   
Joined: 08/01/2020(UTC)
Posts: 12
Location: Zuid-Holland, Den Haag
Hallo Howard

Thank you for this nice workaround to move the barriers of the 7192 Levelcrossing. You mentioned the use of track detectors: are you using IR gates? Is it possible that you enlighten some of the used components and switches you have used and alse the circuits for switching?

Thanx in advance
regards
Henry
Offline ixldoc  
#10 Posted : 19 May 2021 01:28:51(UTC)
ixldoc

Australia   
Joined: 18/11/2015(UTC)
Posts: 219
Location: Brisbane,Australia
Hello Henry,

I built these gates on a plinth as I couldn't use them on my smallish layout. Therefore I used a SPDT manual switch to activate them.
The SPDT switch would be replaced by a latching relay to reverse the current to the motors, or perhaps the electronic equivalent such as an H bridge in which case a relay is not required.

The relay can be SPDT using half wave AC to control the motors, or DPDT relay for DC.
I will draw up a rough schematic of the circuit and possible triggers.

I have used IR detectors across the track years ago for other triggers, but C track makes it simpler to use small isolated sections of track.
The triggers required will depend on whether the track running is unidirectional or bidirectional.
Generally unidirectional only requires two detectors but bidirectional requires four.

If you don't mind the gates coming down at least a full train length away before the train reaches the gates then a C track centre switch which affords bidirectional switching could be used before and after the gates.
The "gates up" centre switch would be positioned the same distance after the gates as before the gates. Hence only two centre trigger tracks are required.
I will post some hand drawn ideas soon ( I don't have a schematic drawing program) and a photo of some suitable motor control modules.

Regards,
Howard.
Offline ixldoc  
#11 Posted : 19 May 2021 02:36:10(UTC)
ixldoc

Australia   
Joined: 18/11/2015(UTC)
Posts: 219
Location: Brisbane,Australia
Hi again,

I found some drawings I did when I set up the gates. I have to do this to jog my memory later!

Boom gates circuit.jpg

The top part shows the basic wiring using 6VAC and diodes to control the motors.
The two switches before the motors are normally closed leaf switches which stop the motors at the down or up positions.
The bridge and associated capacitor supply around 9 VDC.This is used to supply the two flashing red LEDs on the crossing signals (they are 9-12 V items) and the other LED is in the guardhouse.
The lower part shows the basic connections to trigger the gates using a single trigger input module.( the middle module in the photo below).


Latching relays.jpg

This photo shows three possible modules to use for motor control.
The small unit at the top is a flip flop triggered on/of by alternating low level signals into the switch input.
It can source 1500 mA but would need a relay to reverse the power to the motors.

The second from top is a single input trigger module with inbuilt SPDT relay. This will work with half wave AC.
It is the simplest way to control the gates with unidirectional running.

Boom gates triggers.jpg

This looks a bit fussy but shows how to use the third relay module in the photo.
This has both set and reset inputs and works best with bidirectional running.
The circuit allows the entry sensor (gates down)to be close to the gates and the exit sensor (gates up) at least a train length after the gates.
The two sets of "down" sensors are common and connect to the set input , and the two sets of "up" sensors are common to the reset input.
Note as the train triggers sensor A it will also trigger C as it passes through the gates but as this is a latched relay, it causes no change in the gate position.
The same happens if running in the reverse direction with C and A. The same applies to the "up" sensors B and D.
I did mention earlier if you were happy with the gates actuating some distance from the crossing then a single sensor each side some distance from the gates could be used with a single input module.

The more I read this I realise I am no journalist !.
I hope it isn't too confusing but I must say my electronic training is non existent.
Cheers,
Howard.
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Offline Holz1  
#12 Posted : 19 May 2021 12:29:59(UTC)
Holz1

Netherlands   
Joined: 08/01/2020(UTC)
Posts: 12
Location: Zuid-Holland, Den Haag
[img=null]level crossing [/img]Greetings Howard

Tanx for your extensive deliberation on this topic. I think you are able to work as a reporter ; so your explanation is very accurate.

I always draw a circuit before soldering. I am using TinyCad. It is a free Circuit Design software program (https://www.tinycad.net/) with an extensive library.
I thought you operated the circuit by means of an Arduino but then after have seeing the drawings you have used the leaf switch for stopping and activating the 3 volt motors which are switched on and of by the relays (mono stable and/or bi stable)

I am using IR gates to operate my Märklin M electric turnouts so the possibility for using these IR gates also for the level crossing can be done. The signal from the IR gate should be passed on to the H bridge and the H Bridge L298N starts the 3 volt motor and turning the " long brass gear which drives the arcuate (actuator?) gear on the boom shaft".

The leafswitch is activated when the boom descends on top of a small metal tubing ( a plunger) inserted in the support of the boom, and the motor stops. When the train leaves the levelcrossing, the signal is given to rise the booms/barriers and the movement is stopped by another leafswitch which is fitted in the neighbourhood of the counter weight of the boom(s??) under the levecrossing metal housing.

Are you using 2 motors, so 1 for each boom/barrier? How did you attach the leafswitches? did you rise the whole levelcrossing in order to create space below the Marklin crossing area?

So it appears I have still a few questions if you do not mind.
In the meantime I ordered a few steppermotors and a couple of leafswitches the same as you showed above.
I tried also another possibility by using various gears operated by 3 volt motors which would drive long brass gear

I look forward to your reply

Thanx
Henry
The Netherlands
Offline ixldoc  
#13 Posted : 20 May 2021 07:19:52(UTC)
ixldoc

Australia   
Joined: 18/11/2015(UTC)
Posts: 219
Location: Brisbane,Australia
Hi Henry,

I made a mistake in the first picture where I drew track switches to activate the second type of trigger module with only one input. It can only be used with the centre switch activated by the loco slider pickup.
Using isolated track sensors would result in the non latching relay energising and de-energising as the metal wheels passed over the sensor. I guess more electronics could be added to solve this but it becomes too complicated.
If the train has more than one slider pickup then similar problems arise. The module with both set and reset inputs is most suitable.

I have a module with two independent LDR sensors and two output relays which trigger S88 inputs for shuttle use. This could be used for gate control by using a latched relay.
I have also used LDR detection for stopping sections at a station. The LDR fits nicely into C track.
If you have both day and night time running then it is best to have fixed illumination above the LDRs to avoid false triggering.( maybe street or station lamp).

I used two of the 6Volt geared motors in the photos above, wired in parallel. I mounted the leaf switches under the base plate on an angle of aluminium.
A small screw from the base plate above held the angles in place. I did not have to raise the base plate at all.
The nitrile O rings allow a bit of slippage if one boom gets fully up or down before the other. I have not noticed this happening however.
By "arcuate gear" I mean the segmented gear attached to the base of the boom on each side. It is normally driven by the solenoid rack.

Stepper motors could be used I am sure with the appropriate drivers. I opted for the old fashioned analog gear motors for simplicity.
I try to avoid complicated electronics at my age now. This project was finished over five years ago and I have already forgotten the fine details!
I hope this helps a bit and thanks for the interest.

Regards,
Howard.

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