Megapoint Controllers

[ISW]

 

In my opinion no. Most servos do more than 180deg movement. On our club layout Frimingham (0 scale, 2 servo controllers, 10 points, too many signals :-) we had one wrong connection (connector 180 degrees turned) and all servos started with a massive flicker which moved some of them to the mechanical end point of the servo. Minimum 3 of them ripped themselves out of the aluminium profile. They were originally fixed with a drop of cyano acrylate on both sides of the servo. 

 

If you cut the sides of the profile down where actually the servo arm is you avoid the problem. Don't think I have a picture of that in Flickr as I just used this for the latest servos which are already built into the layout. ok just made one.

 

another way is to move the servo forward so the arm cannot catch. sorry for the picture quality. this is already built in the layout in a rather difficult space.

 

......................

 

As you can see I went into mass production of the profiles....

 

Thanks for the clarification / explanation. Seems that it's going to be something I'll have to live with.

 

I like that photo of the mass production of channels. I'll be doing something similar myself.

[ISW]

I can vouch for the extended range of movement on a servo in exceptional situations! Below is a picture from 3 days ago where something caused one of my servo controllers to freak out ( suspect I shorted it somehow) showing the piano wire forced through several point tie bars. The servos had moved about 180 degrees from their usual position but because they are held securely in place by an Alurailtech bracket no obvious damage was done. Fortunately they re-set themselves to normal when connected to a new servo controller and all is now working as normal again.

 

 

My experience in the 12 months that I have been using them is that the Alurailtech brackets are excellent and the stability they create has more then justified their cost.

 

 

Me hopes that doesn't happen to me! Will be very careful about shorting the controller boards.

 

Them Alurailtech brackets look nice, but do seem to need quite a lot of space. I think I'll stick with my cheap-n-cheerful solution due to cost, adaptability, and space requirements.

[Suzie]

Them Alurailtech brackets look nice, but do seem to need quite a lot of space. I think I'll stick with my cheap-n-cheerful solution due to cost, adaptability, and space requirements.

 

Smaller servo motors are available:-

 

https://www.peediemodels.com/proddetail.php?prod=SB1

 

[ColHut]

When the servos are powered up, assuming they are controlled by a megapoints controller, do they twitch and head off to some position as with most analogue servos?

Edited October 25, 2018 by ColHut

[njee20]

The newest boards have reduced chatter by removing the sending of positioning pulses and holding the servo in a continuous state 1 second after they move.

 

Seems to work well, I've got two boards with this feature and they're noticeably silent. I don't find the chatter too bad anyway though I must say even on the "old" boards.

[ISW]

Servo + Microswitch for frog polarity control

 

I'm sure others have come up with similar solutions to the above, but I thought I would show the method I plan to adopt.

 

Servo+microswitch installation.jpg

 

As you can see, it uses the MegaPoints recommended (?) aluminium channel, but improved (no doubt I will get comments ...) by adding two bolts to 'clamp' the servo in the channel (I've seen reports of the servos working loose over time) and an additional bit of channel to support the microswitch.

 

It meets my usual criteria of being 'cheap n cheerful', and 'functional'. Reliability will be tested in the coming days ....

 

I've made 2 examples so far, and it really helps that the whole assembly can be built-up off the layout, and simply screwed to the underside of the baseboard.

 

Servo + Microswitch for frog polarity control at Double & Single Slips

 

Having successfully installed my combined servo + microswitch at some turnouts, I now need to install the servos / microswitches at a double slip. In line with my preferred 'pre-assembly' approach, I've designed a twin combined servo + microswitch assembly for Peco double-slips, again using the MegaPoints recommended aluminium channel.

 

     

 

I hope to get one built and installed soon.

[Rowsley17D]

Some great sevice from Dave. One of my recently purchased relay driver boards was causing all the servos to twitch in unison about once a second when connected to a servo driver. This happened whether the relay board was powered or not. Dave asked for it back on Thursday and a new one was with me this morning (Tuesday). Thanks Dave.

[Rowsley17D]

More great service from MegaPoints. Ordered stuff for my bespoke panel (hope it come before Christmas, Dave) on Sunday and with me Tuesday morning. 

[ISW]

I'm in the process of building my own 'bespoke' mimic panel using off the shelf components. Maybe this will provide some useful information, designs, and/or ideas to others when they want a mimic panel.

 

I'm planning a design using small veroboards for the push buttons & LEDs as below:

This allows for both crossovers and single turnouts, in LH and RH configurations. The whole thing is made doubly complicated by the fact that I found MegaPoints Controller don't always configure the LEDs the same way round! I suppose it rather depends on the orientation of the servo. Hence the 'normal' and 'reversed' requirements. And no, you can't 'just reverse the cable'; I tried that! MegaPoints uses a 3-way cable for the 2 LEDs, and if you reverse the cable both LEDs fail to light. No surprise really, they are diodes after all.

 

Each veroboard is then connected to the MegaPoints controller boards by short plug-n-play cables using Dupont type connectors at both ends.

 

A typical single turnout veroboard looks like this:

 

The LEDs are mounted ~2mm off the veroboard, such that the collar on the LED matches the height of the button assembly, to allow the unit to be screwed solidly to the underside of the mimic panel.

 

The mimic panel for the layout had to be split into 2 parts, due to the print size limitations on my A4 printer. No bad thing really.

The mimic layout took quite a while to design as it had to be schematically correct, be compact as possible, align with the buttons and LEDs, and allow for the space requirements of the underside veroboards (no 'overlapping').

 

The results were like this:

Part -1:

 

Part-2:

 

The mimic panels will be screwed onto the panel assembly box, with the MegaPoints Controller boards strategically located on the base of the box in locations where they will not interfer with the veroboards. This will keep the overall height of the panel to 50mm (2-inches).

 

The panel assembly is planned as follows:

 

You can now see the outline of the veroboards (orange), avoiding the MegaPoints Controller boards (green). 

 

The panel is simple 5mm plywood construction, with 3.6mm plywood for the top (to give visibility to the LEDs & allow the button to protrude). 15x15mm section stripwood is used in the corners for strengthening.

 

I've included a little more information on my layout thread, linked below in the signature block.

 

[47137]

I will be using the servo controller for my next layout, this will be driving the eight sets of points on the layout with a row of switches representing a lever frame.

 

I have made myself a little switch board to let me use the three memories in the servo controller:

 

I haven't found much online about using these memories, but they seem to be useful for me. They will give me three routes and with a bit of luck these will be just right for a smaller layout.

 

This is an old topic and I wasn't sure whether to post here, but I've put a write-up of the panel on my blog:

https://www.rmweb.co.uk/community/index.php?/blogs/entry/23872-route-setting-panel-for-megapoints-servo-controller/

 

- Richard.

 

[ISW]

On 11/04/2019 at 16:36, ISW said:

*snip*

 

Each veroboard is then connected to the MegaPoints controller boards by short plug-n-play cables using Dupont type connectors at both ends.

 

A typical single turnout veroboard looks like this:

 

The LEDs are mounted ~2mm off the veroboard, such that the collar on the LED matches the height of the button assembly, to allow the unit to be screwed solidly to the underside of the mimic panel.

 

*snip*

 

The 'final' design had a few modifications. Firstly, the LEDs were mounted in sockets. This was much easier to control the overall height. Secondly, I found that the LEDs I was using were much too bright, blinding even when looked straight down. So I added a 4.7k resistor into the circuit to reduce the glare. The resultant veroboard is as below:

[ISW]

I've hit a bit of a snag with regards to my fitting of a 4.7k resistor to reduce the brightness of the LEDs (see previous posting).

 

This works just fine for the LEDs plugged into the MegaPoints Controller MultiPanel (I have the V2.1 board), and the brightness was reduced as expected.

 

However, it does not work for the LEDs plugged into the MultiPanel 'LED Expansion' board. In this case, both the LEDs (for a single turnout) are lit, one brighter than the other. The brighter one is the one that should be lit, and the dimmer one shouldn't be lit at all. When I changed the resistor to 10k, both LEDs were almost the same brightness. With either resistor, the LEDs were not being dimmed like they are on the MultiPanel.

 

Can anyone explain what I'm doing wrong, and/or what I need to do to fix the problem?

 

(If I use the pre-made LEDs / cable set that came from MegaPoints it works just fine, so there is no fault on the MegaPoints circuit boards. My LEDs also work fine if I don't put in any resistor)

 

Ian

 

Edited August 3, 2020 by ISW
clarification

[Vecchio]

can you draw the circuit you built? Hard to see it from the vero board. 

[ISW]

24 minutes ago, Vecchio said:

can you draw the circuit you built? Hard to see it from the vero board. 

Here you go, layout of the veroboard, but before the resistor was added. The resistor goes in the Orange Line from the plug to between the LEDs. The track between the plug and the upper LED gets cut.

Ian

[Penrhos1920]

1 hour ago, ISW said:

Here you go, layout of the veroboard, but before the resistor was added. The resistor goes in the Orange Line from the plug to between the LEDs. The track between the plug and the upper LED gets cut.

Ian

Have you got the polarity of the leds correct?  I think it Should be both cathodes  or both anodes on the orange track.

[AndyID]

5 hours ago, ISW said:

 

If I use the pre-made LEDs / cable set that came from MegaPoints it works just fine, so there is no fault on the MegaPoints circuit boards. My LEDs also work fine if I don't put in any resistor

 

 

 

It's hard to tell from the pic but it looks as if the resistor (gold end) might not be properly soldered to the connector pin. That would produce some strange effects.

[leopardml2341]

6 hours ago, Penrhos1920 said:

Have you got the polarity of the leds correct?  I think it Should be both cathodes  or both anodes on the orange track.

On the upper pic, earlier, it does look as though the 'flats' on the LEDs are on the same (left) side i.e. that would mean different legs on the orange track. More difficult to tell on the pic with LEDs in sockets, but easier to swap

 

Edit:

 

if I'd looked at the first veroboard diag properly I needn't have written any of the foregoing......

Edited August 4, 2020 by leopardml2341

[Suzie]

Looks like you need two resistors - one in the black line and one in the red line. I suspect that the orange line has to drive hard to the supply rails in order to turn off the LED that should be dark and it cannot do this if you put a resistor in series with it.

[AndyID]

2 hours ago, Suzie said:

Looks like you need two resistors - one in the black line and one in the red line. I suspect that the orange line has to drive hard to the supply rails in order to turn off the LED that should be dark and it cannot do this if you put a resistor in series with it.

 

I think that explains it. The MP board has 1K resistors in each leg.

[AndyID]

This is what you end up with when the MP board is trying to turn on the upper LED.

 

 

The upper LED will be on but the lower will be passing some current too. The situation is reversed when the MP board is trying to turn on the lower LED.

[ISW]

Thanks for all the replies and ideas. I'll be trying putting a resistor on each of the LEDs to see if that works (using a breadboard to test the circuit).

 

Form what I understand (?) the LEDs are in a circuit as below:

 

The LH diagram shows the LH LED driven, and the RH diagram the RH LED driven. I put a 3v supply to the +/- as shown, and the 'correct' LEDs do light (even when I bridge the -ve to both the orange & black lines in the LH example).

 

But when plugged into the 'expansion panel' one LED is bright and the other dim, in both the LH & RH configurations.

 

Yes, I gather that the multipanel (MP) has a 1k resistor in circuit but, looking at the 'expansion panel' (EP) this has the same 1k resistors. So none of this explains why my little veroboards work correctly when plugged into the MP, but not when plugged into the EP.

 

Ian

 

[AndyID]

You'll have to reverse engineer both circuits if you really want to answer that. Alternatively you could ask the person that designed them.

[ISW]

46 minutes ago, AndyID said:

You'll have to reverse engineer both circuits if you really want to answer that. Alternatively you could ask the person that designed them.

Andy

 

Yes, I'm thinking I'll have to email Dave at megapoints controllers for an explanation and guidance.

 

Ian

[ISW]

On 05/08/2020 at 18:14, AndyID said:

You'll have to reverse engineer both circuits if you really want to answer that. Alternatively you could ask the person that designed them.

 

On 04/08/2020 at 17:40, Suzie said:

Looks like you need two resistors - one in the black line and one in the red line.

 

The short reply I received from MegaPoints was that putting resistors on the 'uncommon' legs would be the right thing to do, and that has proven to be correct. Looks like I'll have to relocate my resistor and add a second one as well to my little veroboard. It's going to be tight for space ...

 

What I never did find out, though, was why the single resistor works with the Controller board but not the Expansion board.

 

[AndyID]

41 minutes ago, ISW said:

 

 

The short reply I received from MegaPoints was that putting resistors on the 'uncommon' legs would be the right thing to do, and that has proven to be correct. Looks like I'll have to relocate my resistor and add a second one as well to my little veroboard. It's going to be tight for space ...

 

What I never did find out, though, was why the single resistor works with the Controller board but not the Expansion board.

 

 

If the controller board does not actually have the 1K resistors it would work that way.