grob1234

Especially if they're 'into' DCC or say 'sat' instead of 'sitting' etc.

Similar to parents evening, Sir just needs to allow 5 minutes per person. Once time is up (Mo would be an excellent time keeper) the person would be escorted away. Easy?!

Definitely one of my favourite layouts. Well done to all the crew.

Unfortunately, that would require too much wiring for the benefit gained. I've definitely buggered the relay, it worked fine before hand. It does seem the CDU/Relay combination is perhaps not the one. Never mind, it was worth an exploration.

OK that's good to know about the CDU. And part 2 also makes sense as well. As you can tell, its all a learning process for me - I'll take your word for it that there's a large spike of reverse voltage. For me, in order to understand why things are as they are, its important to figure out where the excess voltage comes from, which you have explained. Thank you.

This is my theory too. At “rest” the cdu output is 23.4v or thereabouts, but I don’t know what it spikes to upon operating the switch. More than 23.4v I’d have thought, and yes I only have a basic multimeter, so I’m not surprised it can’t register the momentary voltage spike. The switches are (on) off (on) sprung to centre type SPDT type recommended for solenoid point motors. This is the annoying thing here… the test with a stable 12v supply produced exactly the results I was hoping for! So the theory and wiring was correct. With regards to relays, could it be possible that a relay with a 24v coil might be more appropriate? Would the 24v relay be able to handle a higher number of amps?

Yes I did exactly this to test the relay, and it worked perfectly. Now, having used it connected to the CDU etc, its broken. Not to worry, it was only an attempt to improve reliability. I'll list the remaining items on Ebay and try and recoup my money!

Well, thank you all for your help and replies. I’m obviously at the limit of my understanding of electrical stuffs, so I’ll retire gracefully and put the idea of latching relays for changing frog polarity to bed. 12v latching relays now available on EBay!

I wasn’t sure how to measure the output of the cdu, as it’s momentarily on, I couldn’t get an accurate reading with my multimeter. Is there a way to measure it? Edit, I have measured across the terminal. 23.4v… there’s my answer confirmed… if only I figured this out before hand. Doh! Even the 24v relays have a max set/reset voltage of 19.2….

Yes they do. In short, I think the CDU has supplied too much voltage and blown the relay. The CDU outputs DC voltage. It is this exact model: https://www.layouts4u.net/other-products/track-related-items/block-signalling-cdu1c When testing the other relays with 12v DC, there is an audible click, and you can feel it inside the relay, and the output changes as you'd expect. I'd imagine 24v relays would work well, I just don't want to spend another £24! Oh well, live and learn. The relays have 10 pins, and testing on the bench has shown them to work exactly as advertised, so I am confident I have the right type, just the wrong coil voltage.

Its these ones Jeremy: https://www.rapidonline.com/Catalogue/Search?Query=Hongfa HFD2%2F012-S-L2-D PCB Signal Relay 12VDC DPDT 2A&Size=20 What concerns me is that the relay switched 'on the bench' with a 9v battery, and now, the same relay won't switch under the same conditions with a 9v supply. I'm just charging up a 12v power supply, to see if that works....

How do you mean? My limited understanding is that the power to move the solenoid comes from the switch via the CDU, and the solenoid requires the power of the CDU in order to move it. How would the relay be switched in this instance? They are Hongfa 12v Relays, the power to the CDU is 16v AC and the output from the CDU is whatever it is, as I couldn't measure it as the power is too momentary. I'm guessing there are too many volts going through it, and I've blown the relay!

Well done that man! 12 11 Latching relays now available on Ebay...

Well, I said I'd report back. Got my 12 Latching Relays from Rapid Online, and they certainly were Rapid. Ordered at 5pm, came the next day at 9am! Excellent! Tested a 12v relay with a 9v battery. Heard the little click. Relay works, so far so good. Get the multi meter out test the output, and yes its working as advertised. Continuity switches between +ve and -ve. Remove the power and there's no continuity at all. Ok good that seems to make sense, if the relay isn't powered, the little electro magnet inside or whatever isn't making a circuit. Wire one into the layout feeling happy that I may have found the solution. Gingerly apply power, and the point works flawlessly in the straight on configuration. Throw the point. Apply power. Nothing. Test the relay. No click. Remove and test again. Nothing. Test with multi meter. Circuit is permanently open one way and won't switch back. I'm assuming too much voltage has come through the relay and welded it to one side, either way, its buggered! Really not sure what to do about this. I have a CDU supplying the point motor, I chose 12v latching relays assuming the voltage would be low. Without spending another £24 on another set of 24v relays, it seems my dream of perfect point polarity switching on the cheap is over.

I can see that would work well Keith. Nice and simple!

Nice, neat little set up there. I doubt very much mine will look as refined!

Thank you all for the informative replies. The answers I have received show that this isn’t as straightforward as is sometimes suggested, but is a reliable way (if implemented correctly) of improving the reliability of this type of point motor. It is also highlighting things I have not come across in my previous research, so I’m very appreciative of this. i had noticed the gauge master version - I suppose I’m trying to keep costs down, so the DIY route and a bit of easy soldering is attractive. With regards to diodes, I might as well order a few at the same time and see how I get on incorporating them into the wiring. Although as Suzie mentions, it seems they “should” be present in the normal point motor wiring anyway! Thank you for your points (excuse the pun) Suzie. I’ll use both sets of contacts on the relay as you suggest, it is not something I thought about but makes sense. I will also check the voltage output. The layout is small, and the wiring runs are not long, and I have 2 dedicated CDUs so I hope the voltage will be sufficient to fire a 12v relay, I’m assuming I’ll need about 9v based on what you’re saying. Although I didn’t intend this to be a thread discussing the merits of solenoid point motors, the reason why they are used is obvious. They are readily available, they are cheap, relatively easy to install, reliable, and as pure point motors they work well. The switching element can be tricky, as I have found, hence the need to improve what I have. Additionally, people may not be aware of servo operated points, I certainly wasn’t at the time I made this layout, and higher cost options (cobalt, tortoise etc) may not always be viable. For the next N Gauge layout that I am currently planning, I will be using slow action point motors with built in switching. You live and learn, however, I still feel that solenoid motors definitely have a place. I think I have enough to go on, I’ll order some relays and some other bits and see how I get on. I’ll try and post some pictures and draw up some wiring and specs for anyone who’s interested in future. Many thanks, Tom.

Thank you very much Jeremy, that’s exactly what I needed to see. I wouldn’t have got the wiring like you have indicated for the relay without an awful lot of head scratching, but it makes sense now. I forgot about port c from the seep pm1 in my original post, but it’s there on my layout and all tested and working fully… except the frogs… sometimes! It would make sense if C was my common return wire. It’s a while since I did it. I think I’ll go with this, and might risk foregoing the diodes and keep it simple. Once again thank you for your succinct reply.

Hello, Please forgive this post, I know it duplicates some aspects that have been posted before, however not being an electrical wizz, I need things in a simplified format. I currently have an N Gauge layout (DC Operation), and Peco code 55 turnouts with electro-frogs. I use Seep PM1 point motors, which are used to change frog polarity. However, they are unreliable in terms of changing polarity, as the throw is not sufficient at all times to ensure changeover 100% of the time. Please note I DO NOT want to change the point motors, I simply wish to improve them. Currently, they are wired as follows, in the standard manner. I use momentary (on)-off-(on) SPDT switches via a CDU. This will not change. Having read @Brian website https://www.brian-lambert.co.uk/Electrical_Page_3.html, I understand the need for a Twin Coil 12v Latching relay, and he recommends https://www.bitsboxuk.com/index.php?main_page=product_info&cPath=253&products_id=1924 To me this seems like any other electrical component, and as I need 12 of them, is this https://www.rapidonline.com/hongfa-hfd2-012-s-l2-d-pcb-signal-relay-12vdc-dpdt-2a-71-4712 the same thing, but at a better price? Or could someone recommend a cheaper equivalent product? In terms of wiring in the latching relay, I don't understand the need for the diodes Mr Lambert shows? I don't intend to have LED's for route indication, and so my idea would be to wire it in as follows: Would this work without the need for diodes? From the wiring diagram below, I'd be using terminals 1 and 10 to operate the latch, and 13, 11 and 9 for the frog. I have taken the wiring for the relay from the datasheet thus: Any (simplified) help would be much appreciated.

Bawtry is a location I have for a long time wanted to model, and it'll remain that way until I get a space big enough to build it! Please show more of your superb looking model!

Frankly, I'd be disappointed if it wasn't operated by a shower of sniggering schoolboys!

Kit building is possible.... Buffers now fitted, and its weathered too. Economical? No! Enjoyable? Immensely! No one else on the planet has this particular model, that makes me happy. A W1 conversion:

You know what Mick, I don't always agree with what you say, but in this case I do think you have a point. In my opinion, £70 for a wagon like this is a lot of money. You are of course right to observe that most of the end detail is obscured when the train is close coupled. So why is the detail there? Well, I reckon it's all to do with margins. When they complete the CAD work and make the 3d test prints, they might as well do all the detail, it'll cost them very little at this stage to incorporate. They can then market the wagons as 'premium' products and charge accordingly, therefore making more profit. The cost of the detailed versus plain ends would be not much I'm guessing at manufacture, but probably at least £10 or £15 in terms of additional margin during sale. Just my 10p, I'm no expert, clearly!

A masterclass in operation.... 🤣

Yes - 3 minutes at the bench followed by about an hour and a half of the above tasks... I know it well.