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Suzie

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Posts posted by Suzie

  1. I suspect that you may have a faulty relay here. Those you have are good for up to 27V so you cannot cook them from the 24V output of your CDU.

     

    The most likely thing that has happened is too much current through the contacts welding them together due to a shorted load when testing. Sometimes a good beating with the wrong end of a big screwdriver can free the contacts but it might be permanently dead. Carefully check that you have wired the contacts correctly, they are not always connected intuitively.

     

    I would not give up yet - plenty of people have achieved excellent reliability so stick with it.

  2. Just to add a few notes:-

     

    1. Hongfa relays are fine for this. I have some twin coil latching HFD3 relays (slightly smaller than the HFD2 types but adequate for the task). They will still switch 4A (see point 2) and carry quite a bit more current.
    2. Use both sets of contacts in parallel to increase the amount of current that the frog switching contacts can handle. This will improve reliability over the long term especially if people are prone to run the point the wrong way and short on the frog.
    3. Because of the extremely low resistance of the SEEP motors the voltage at the motor is often very low and may be insufficient to fire a 12V relay if mounted near the motor even when fed by a CDU. It is best to mount the relays near the control panel to ensure that sufficient voltage is available. I understand this can be inconvenient on a DC layout, so if you don't want the extra wiring you might need to select the voltage of the relay coils carefully to ensure reliable operation. I have seen installations where even when using a CDU giving out 24V  (the typical output of a CDU fed with 16V AC) there was less than 6V available at the point motor due to resistance in the switches and wiring. Some CDUs will run at up to 35V - it can sometimes be helpful to use a regulated 35V DC supply to get the most out of a CDU if your wiring is not the fattest cable. Consider using a cheap adjustable DC-DC convertor running from a 12V supply to give you a cheap source of 35V to the CDU that can be adjusted lower if required.
    4. While the inverse parallel diodes across the coils are only essential when using semiconductors to switch the points - they will reduce arcing across the switches and extend their life. There will be far more back EMF (in terms of power) from the point motors than the relays so even if you don't have relays you should use inverse parallel diodes (no one will tell you this!).
    5. You say that you don't want to change your motors in which case you will have to live with the shortcomings of what you have - but in future consider using the solenoid motors with higher resistance coils (Peco PL10E or PL10EL for example) because the lower currents involved result in much higher voltage being available near the points for powering latching relays and you don't need to worry so much about super-fat wiring to the solenoid coils, CDU and switches.

    Using latching relays is super-reliable if you can implement them correctly. I got my good results by beefing up the wiring (especially from the CDU to the control panel), upping the CDU output voltage to 35V, and mounting 24V latching relays near to the control panel. The Hongfa relays will typically fire at about 75% of the rated voltage and will take 150% of the rated voltage so you do have a nice big window to play with (for example a 24V relay will fire at 18V and will be OK at 36V so will not be damaged if a solenoid goes open-circuit and will take a bit of loss in the wiring).

     

    I have probably raised more questions than I have answered but what you are trying to do is not as simple electronically as it first appears.

    • Thanks 1
  3. 10 hours ago, Fastrider said:

    I've installed a BLOCKsignals CDU, nice bit of kit.  It's working with my Gaugemaster Combi accessory take-off as this produces 16 - 18v AC no problem.  I want to hide the PSU away though so I am looking for a standalone PSU that willwork.  I've tried a laptop PSU that supplies 20v/2A DC but this isn't sufficient for the CDU to operate correctly.  Can anyone recommend the source of an AC or DC PSU (1A is fine), AC needs to be max 24v and DC needs to be max 35v I'm told.


    Thanks in advance

    The 20V PSU should be OK in normal circumstances - did you wire it up the correct way round?

     

    16V AC will give you around 25V at the points so about 50% more power than the 20V PSU.

     

    If buying a dedicated PSU for the CDU get a 24V 2A unit.

    • Like 1
  4. I would do it a little differently:-

     

    Dumbell.jpg

     

    You can either:-

    1. Use reversers for each of the orange and green sections.
    2. Or better still use the position of the crossover formed by points A and A' to control the polarity of the orange section, and the position of crossover B and B' to set the polarity of the green section.

     

    The advantage of doing it this way is that you will only have to switch polarity when running trains from the bottom to the orange section and from  the top to the green section. Both of these will typically only occur when trains are being reversed in the station resulting in switching the polarity while the train is stationary. Trains running all the way around the dumbbell (probably most trains) will not need to go through a reversing section when running.

     

    As for wiring - points A and B' will have insulated joiners on the outer rails rather than the frog rails and you will need to double isolate the left end of the green section and the right end of the orange section.

    • Like 2
    • Interesting/Thought-provoking 1
  5. The output voltage from the Multimaus amplifier is purely dependant on the voltage coming in from the power supply. In the olden days they were supplied with a 230V transformer which gave out around 19V at the track when powered from 240V mains supply. 19V is probably a bit high for most smaller decoders to be happy - especially if any shorting is going on because the resulting current spikes will be a bit high.

     

    It looks like more recently they are being supplied with a DC power supply which should be more suitable. I would recommend that you see what is coming out of your DC supply, and if it is more than 15V perhaps get a 15V 4A DC supply instead.

  6. Yes, you can do it, but you will need to consider a couple of things:-

     

    1. The resistance of some point motors can be as low as 4 Ohms (2 Ohms for two in parallel), so you will need to ensure that the wiring and switches do not provide any resistance at all. It is very easy to get a few Ohms of resistance in the circuit which will see perhaps as little as 6V at the point motor at the start of the capacitor discharge (voltage drops after that) - don't be surprised if the relay does not fire if you are using thin wiring.
    2. At the other extreme the CDU will give out around 25V when fed with 16V AC, which can be too much for a 12V relay if the point motors become disconnected.

    In my experience to get reliability when using latching relays with solenoids I use a 35V DC supply to the CDU (rather than 16VAC) to give a bit more oomph, and use 24V latching relays mounted near the control panel (with a long frog feed). Trying to simplify the wiring like you intend just means you will be using very fat wires. Using the higher voltage allows you to get away with thinner wires. The ECM unit is rated up to 24V AC so should be good for 35V DC.

    • Informative/Useful 1
  7. When I see a layout I like to look at it and relate to what I know about what is being modelled. That has the effect of making models of the modern era set in Great Britain of instant interest as it is something I have seen. I used to walk quickly by anything I was not familiar with but would dwell for a long time on any British electric layouts because the electrified railway was the normal railway for me.

     

    Over the years I have researched a lot, and that has expanded my horizon of what I know, and therefore what I can relate to. I will spend a lot of time looking at American layouts now because I know a lot about American, even if I still have trouble identifying most of the locos!

     

    If I see something well modelled that I am not familiar with I will try and engage the operator to find out a bit more about what has been modelled. This usually starts a thread of research which eats up a lot of browsing time! Layouts are so much more interesting when you know what it is. If it has an information board I will read that to get more of an insight.

     

    Nowadays the only layouts I spend little time at are the ones with Great Western steam locos on them - I feel I have seen enough to last a lifetime.

    • Like 7
    • Interesting/Thought-provoking 1
  8. It looks like you don't have enough current available for the momentary short when the train enters the the reversing section.

     

    I am not familiar with the particular hardware you are using, but it may be that the DR5013 is taking too long to switch which may be due to a high impedance somewhere in the wiring either feeding the DR5013 or in the track feeds.

     

    Yes, different sound locos will draw different amounts of current so you have one loco that just draws a few milliamps extra that is the straw that breaks the camel's back.

  9. Simple answer:- There will generally be four wires going to the Next-18 socket, and you can just splice these on to your decoder wires or solder directly to the next-18 decoder (many small decoders are just the Next-18 decoder with wires attached instead of the plug).

     

    Issues that will occur:-

    1.  Next-18 (and PluX) sockets include a defined space that the decoder will fit in to. Using a non-standard sized decoder will most likely mean that you will have to clear some space somewhere in the loco for the decoder and wires, especially for a sound decoder with a speaker and stay alive. Next-18s socket has room for a sound decoder.
    2. Next-18 (and PluX, and MTC-21) use very reliable connectors that are likely to make a connection when plugged in that will outlast most amateur soldered connections (especially if lead is involved).
    3. It is an awful lot of work to no advantage, especially when Next-18 (and PluX) decoders of the finest quality can be had for £25.

    The Next-18 socket is nothing like the somewhat less reliable NEM651 6-pin or NEM652 8-pin connectors which you might consider replacing with a hard wired connection for a good reason.

    • Agree 2
    • Thanks 1
  10. Clearly a layout of this type will have some compromises to be able to accommodate both DC and DCC. The big question is which way the compromises go - and how much of an I.T. project you want to make it.

     

    It sounds like you already have a good system to manage queuing in the fiddle yard, so why not just enable DC running on the DCC stock to facilitate using the DC queuing system where DCC trains are stopped by the driver when they enter the fiddle yard, the points are changed to the next clear road and relays switch over to DC - the reverse happens when leaving.

     

    I suspect it might be a lot easier and cheaper for the club to pay for DCC fitting of DC members' stock (£25 per loco - you can probably fit forty or so locos for what the DC wiring is going to cost) to just make the layout full DCC and a lot easier to wire - but you have the brief you are given!

     

    • Agree 1
  11. 6 hours ago, Pint of Adnams said:

    ...The last train on 5th May 1951 comprised an ex-W&U Tram Car E60462 sandwiched between the two ex-Stoke Ferry Brakes E62261 & E62262. The train locomotive was J69/1 68578.

     

    If the last train could not use both tramcars, then I guess it is most unlikely that they were used together. 92 passengers is a lot (two tramcars and a brake) - that would take three Osborne buses to replace the service!

     

    I guess I will just have to invoke rule-1. I have a couple of Hattons brakes on order for modification (new wheels, move the guard's ducket and sort the end windows) so I can eventually make up a rake of  Brake-Tram-Tram-Brake for a Treacle Mines special excursion to Tudwick for 116 passengers...

    • Like 2
  12. I have my BR tramcar pair now, and I was looking at pictures to see what a likely complete train would look like, but I have not seen a train with both tramcars in it in BR days. I have seen:-

    • Two Stoke Ferry 6-wheel brakes.
    • One Stoke Ferry Brake and a tramcar.
    • Two stoke Ferry brakes around a tramcar.

    Surely they must have run together at some point!

    • Interesting/Thought-provoking 1
  13. The formulas are different for different manufacturers. Typically the decoder will have a regular polling time where it will add or subtract a an amount from the current speed until it reaches the target speed each time it polls. There are better ways to do it so some might adjust the amount added to create a smoother transition to the target speed.

     

    Storage on a decoder is not a big issue nowadays, and there is plenty of processing power to do what is quite a simple task in the scheme of things.

     

    Have a look at the source code for some of the DIY decoders that you can make such as the MERG or DIY Decoder Project to see how it is done.

    • Thanks 1
    • Informative/Useful 1
  14. I guess a key question is how are you operating your points.

     

    If you are operating the points and signals from your throttle then you might like to power the accessory bus direct from your Z21, and using a booster to power the track.

     

    If you are using a computer or similar with software like JMRI to operate your points and signals then it might be worth investing in a Sprog3 to run your accessory bus as a seperate command station.

  15. I would recommend that you try a Bachmann E-Z Command which are available from eBay or similar:-

     

    https://www.ebay.co.uk/itm/204472640662

     

    spacer.png

    For £50 it gives you a nice DCC controller to test your new purchases, and if you grow out of it you should be able to move it on with little loss (if you don't find it too useful and want to keep it!)

     

    It only has limited addressing, limited access to functions (so not ideal for fancy sound), and very limited CV programming capability, but is very, very easy to use. You would be surprised at how often these are used at exhibitions (I use one on one of my exhibition layouts).

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