Reliable frog switching on DC

[Ben Alder]

5 hours ago, stewartingram said:

I'm surprised nobody has commented on an idea published in Railway Modeller

Very interesting - what issue was it in, please.

[Tony Cane]

On 25/11/2021 at 13:06, spikey said:

Alas, particularly in the case of those points which are the most troublesome, there's either insufficient space for microswitches or the motors are surface mounted.  

For surface mounted locations this might be suitable.

[Tony Cane]

On 25/11/2021 at 13:06, spikey said:

Alas, particularly in the case of those points which are the most troublesome, there's either insufficient space for microswitches or the motors are surface mounted.  

For surface mounted locations this might be suitable.

[Chris M]

I use self latching relays. The cost about £3.50 each. I just come t them to the feed to the point motor and they work fine.

 

Simple, cheap, effective and reliable. You have to make sure you use the correct relay though. You need to have the type with two coils .

[stewartingram]

51 minutes ago, Ben Alder said:

Very interesting - what issue was it in, please.

As I said in my post - I have no idea!

 

edit to add:

 

After a bit of searching, Dec 2015. There was also a follow up letter , in the next issue or so, with a diagram. Basically, the wire from the centre switch contact originally was taken to the top of the panel; a neater solution was described to put it on the underside of the panel.

 

Edited November 26, 2021 by stewartingram

[melmerby]

1 hour ago, spikey said:

Thinking further about this, if I were to swap my four solenoids for MTB motors (assuming of course that it's ever possible to buy some), how might I go about switching my pair of facing three-ways?  They form three storage loops, and at present the solenoids are activated by the CDU via a basic diode matrix and three push-buttons, one for each loop.  I can't see an obvious way of keeping things that simple ...  

Which three ways?

It depends whether they are code 75 or code 100 peco or a n other.

 

The code 75 work as two separate turnouts and no special operation is needed.

The code 100 are a different case. if using MTB motors (i've a box of 8 sitting in front of me), I assume you could wire those via a matrix to ensure only correct sequences are possible.

They work off 12v and they switch off at end of travel. I would use 1N400x series diodes rather than smaller signal diodes. (N.B. I haven't tried it but can't see a insurmountable problem)

[spikey]

1 hour ago, Chris M said:

I use self latching relays. The cost about £3.50 each. I just come t them to the feed to the point motor and they work fine.  Simple, cheap, effective and reliable. You have to make sure you use the correct relay though. You need to have the type with two coils .

 

Sorry, but I can't make sense of that.  You use self-latching relays to do what?  What type exactly (eg a part number?)?  How exactly do you "just" connect them to the point motor?  

41 minutes ago, melmerby said:

Which three ways?

It depends whether they are code 75 ...

They are code 75 and the diodes are 1N400x.  So are you saying that instead of the "outputs" of the existing matrix going from the CDU to one coil or the other of the relevant solenoid as required, they would simply feed the 12v to the appropriate side of the BMP unit as if from an SPDT switch?

[Happy Hippo]

31 minutes ago, spikey said:

 

Sorry, but I can't make sense of that.  You use self-latching relays to do what?  What type exactly (eg a part number?)?  How exactly do you "just" connect them to the point motor?  

 

I would refer the honourable gentleman to my post on page one of this thread where I gave a link to the appropriate  Gaugemaster web page. On the page was a further link to the wiring of a relay as supplied by GM with the express purpose of crossing nose switching. This included an exploded diagram.

[melmerby]

16 minutes ago, spikey said:

 

They are code 75 and the diodes are 1N400x.  So are you saying that instead of the "outputs" of the existing matrix going from the CDU to one coil or the other of the relevant solenoid as required, they would simply feed the 12v to the appropriate side of the BMP unit as if from an SPDT switch?

Do you have this arrangement for the fiddle yard?

If you are prepared to hold the switch down whilst the motor moves I would think it should work as before, powering the equivalent motor at each end at the same time.

 

I must be honest I can't visualise exactly the configuration of the diode matrix at the moment due to brain fog! I'm guessing to a certain extent!

I'll have another go later on.

 

[spikey]

10 hours ago, Happy Hippo said:

I would refer the honourable gentleman to my post on page one of this thread where I gave a link to the appropriate  Gaugemaster web page. On the page was a further link to the wiring of a relay as supplied by GM with the express purpose of crossing nose switching. This included an exploded diagram.

 

And if you would care to refer back to my post immediately below that, you will see that on the first line it says

 

On 25/11/2021 at 10:10, spikey said:

Thank you gentlemen.  Points are wired as below, and relays as per those diagrams.

 

[spikey]

9 hours ago, melmerby said:

Do you have this arrangement for the fiddle yard?

If you are prepared to hold the switch down whilst the motor moves ...

 

That is indeed the arrangement of the facing three-ways.  If it ever gets light enough, I'll try and get a snap of the diodes later on.

[Izzy]

12 hours ago, spikey said:

 

They are code 75 and the diodes are 1N400x.  So are you saying that instead of the "outputs" of the existing matrix going from the CDU to one coil or the other of the relevant solenoid as required, they would simply feed the 12v to the appropriate side of the BMP unit as if from an SPDT switch?

I believe that would be correct. Just 12v of course, not through the CDU. But if you use a stud and probe type control then you would have to hold the probe on till the motor/s finished moving, not sure how quick they are. An alternative method to the matrix would be DPDT’s, one side to move the motor the other simple interlocking with the other motor switch. To stop conflicts with route setting. You know, each other’s power supply routed through the spare side. Would then give a visual indication of the route set. 

[melmerby]

12 minutes ago, Izzy said:

I believe that would be correct. Just 12v of course, not through the CDU. But if you use a stud and probe type control then you would have to hold the probe on till the motor/s finished moving, not sure how quick they are. An alternative method to the matrix would be DPDT’s, one side to move the motor the other simple interlocking with the other motor switch. To stop conflicts with route setting. You know, each other’s power supply routed through the spare side. Would then give a visual indication of the route set. 

One 3-way multipole switch would do it, then each position is one siding.

 

The MTB motors take about 1 second to move

 

[Harlequin]

On 27/11/2021 at 08:44, melmerby said:

One 3-way multipole switch would do it, then each position is one siding.

 

The MTB motors take about 1 second to move

 

Just what I was thinking.

 

Here's one way to do it using a rotary 3-way, 2 pole switch:

 

Note that this diagram doesn't show the wiring for the frogs.

 

So you just turn the knob to set one of the three routes.

 

Edited April 12, 2022 by Harlequin
Fixed small mistake in wire crossings

[WIMorrison]

The disadvantage to these are that you cannot have a train entering on track one and another leaving on track 2 

 

however with DC that might not be an issue anyway

[spikey]

Thank you very much indeed, gentlemen.  I'm rather partial to rotary switches

 

Right then, all I have to do is save up some money and find somewhere that actually has four of these things which I can buy ...

[Nigelcliffe]

4 hours ago, spikey said:

Thank you very much indeed, gentlemen.  I'm rather partial to rotary switches

 

Right then, all I have to do is save up some money and find somewhere that actually has four of these things which I can buy ...

 

Rapid,  Farnell,   RS....    Electronics suppliers keep hundred or thousands of each type in stock.  

 

 

- Nigel

[spikey]

35 minutes ago, Nigelcliffe said:

 

Rapid,  Farnell,   RS....    Electronics suppliers keep hundred or thousands of each type in stock.  

 

Thank you, but the recurrent theme in my later posts is that nobody has any stock of MTB point motors.  It's them I need to find a supplier of.

[WIMorrison]

DDC Train Automation is the UK Importer and get stock regularly - a couple of weeks ago he had a couple of  hundred, drop him a line and ask when the next order is due

[Ben Alder]

https://www.ebay.co.uk/itm/154618596620?hash=item23fffc8d0c:g:MMkAAOSw6BlgVHQq

[spikey]

Cheers for the link.  I actually stumbled upon it earlier this afternoon.  I'm still in shock at the likely cost of solving this little problem ...

[Izzy]

2 hours ago, spikey said:

Cheers for the link.  I actually stumbled upon it earlier this afternoon.  I'm still in shock at the likely cost of solving this little problem ...

 

Yes... that's why I've gone down the home brew DIY hacked servo route....about £6 a throw for the servos (MG90's) and two switches needed ( 2x expo tools micro DPDT's). But then I like messing around making things out of bits and pieces. But the MTB's do look nice, about the same as Tortoise/Cobalt I think but far smaller and probably more powerful and versatile.

[WIMorrison]

Extremely flexible in set up options and much easier to get in the correct place than either tortoise or cobalt

[melmerby]

6 hours ago, spikey said:

 

Thank you, but the recurrent theme in my later posts is that nobody has any stock of MTB point motors.  It's them I need to find a supplier of.

I've got 8 in stock.

You can have them at a special Black Fraud day price of £30 each plus £10 Postage (each)

 

6 hours ago, WIMorrison said:

DCC Train Automation is the UK Importer and get stock regularly - a couple of weeks ago he had a couple of  hundred, drop him a line and ask when the next order is due

He gets regular stocks, I waited a couple of weeks with the stock at 0 then one day he had hundreds in and I got my order in smartish.

 

I like the size, they are way smaller than Tortoise (which I have loads of on my layout) or Cobalt and easier than servos to set up.

I managed to mount a couple on a crossover on a lifting section, they almost vanished into the 21mm thick wood I was using, once I routered a recess for them.

They are a little noisier than Tortoise/Cobalt motors but not unduly so and need more current but a normal 12v or so supply is fine.

 

[melmerby]

Back in stock (299 as I write)

https://www.dcctrainautomation.co.uk/mp1-point-switch.html