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Relays - non latching or latching?

Discussion in 'General Electronics Discussion' started by Barrysteel, Mar 1, 2016.

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  1. Barrysteel

    Barrysteel

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    Mar 1, 2016
    Hi
    I have a model railroad. For this I bought a 'fast clock', a clock that runs quicker than normal to 'scale' time in line with my HO scale trains. Now, on the PCB that runs the 'fast' clock there is a 20 terminal block that can be used to power on and off up to sixteen 12v lights housed in miniature buildings. Each of the 16 outputs are aligned with the 'fast clock' and each are programmed individually to switch on and off. For example, an output may be programmed thus.... 07:00 on - 09:00 off, 18:00 on - 10:30 off whilst another may be 08:00 on - 10:00 off, 17:30 on - 11:30 off.

    OK.... but running the light sequences directly from the 16 sequenced terminals is not practical as 12v is shared amongst the 16 terminals meaning that power is reduced according to how many are switched to on at any time. In other words lights in building get brighter and duller according to how many are on at any one time.

    It is therefore more practical for buildings to be remotely powered (thus assuring constant power when on) and to use relays. Each relay is directed by an attached 'fast clock' terminal to switch the remote power on and off according to the sequenced times as described above.

    Finally, here's the question. What relays do I need to get to achieve this? Do I need latching or non-latching relays? Do they need to be NO or NC? Or am I completely wrong in my logic about how to set this up? Or how would you go about it?

    Thanks in advance

    Barry
     
  2. AnalogKid

    AnalogKid

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    718
    Jun 10, 2015
    If the lights get more dim as more are turned on, that indicates that the power source for the lights is not well regulated or is being overloaded.
    What is the 12 V source? manufacturer, model number, photo, etc.
    AC or DC output?
    Regulated?
    Max rated current?
    Number of lights?
    Power or current per light?

    ak
     
    duke37 likes this.
  3. duke37

    duke37

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    Jan 9, 2011
    You could think about using a transistor instead of a relay, Smaller and cheaper.
     
  4. Barrysteel

    Barrysteel

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    Mar 1, 2016
    Interestingly, the PCB is marked as 12v but the supplier states to use 9v. Therefore I have a direct plug in transformer MPE 961 Series, UK made, 9v DC 300mA. So far only 4 lights 12v each. In future will be more like 18 lights, all 12v.
     
  5. duke37

    duke37

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    771
    Jan 9, 2011
    But what is the current of each bulb? If no current is specified waht is the power?
     
  6. Barrysteel

    Barrysteel

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    Mar 1, 2016
    'So far only 4 lights 12v each. In future will be more like 18 lights, all 12v.'
     
  7. dorke

    dorke

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    665
    Jun 20, 2015
    1. Driving 12v lights with 9V source is already very dim...

    2. Get a higher amperage 12V source,you may have one sitting somewhere.
    A 1A or more regulated SMPS wall-wart would be good,like this.

    3. Check the wiring,should handle the current needed.

    4. If possible, switch to LED lights,I would go for the 2ma bright ones.
     
  8. Barrysteel

    Barrysteel

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    Mar 1, 2016
    Hi Dorke
    Yes agree with all the above.... Thanks! And there is always the option of putting in a transistor. However, going back to the original question, if I wanted to use a relay, what relay what I use? Latching or Non-latching, NO or NC?
    Thanks
    Barry
     
  9. Barrysteel

    Barrysteel

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    Mar 1, 2016
    Hi Dorke (again)
    Yes totally agree with using LED's and this is what I will do.
    Thanks
     
  10. duke37

    duke37

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    771
    Jan 9, 2011
    It all depends on what signal you have, if it is active whenever the light is on, then a NO non-latching relay would be used.

    If you use LEDs, then they will probably take less current than a relay coil.
     
  11. dorke

    dorke

    2,342
    665
    Jun 20, 2015
    I agree with @duke37.
    I can add that if you use LEDs you can easily make it an all electronic thing without any relays,and it will be much cheaper.

    Can you please give more details of that "fast clock" you are using?
    It may be that you can connect the "fast clock" to activate the lights directly.
     
  12. Barrysteel

    Barrysteel

    6
    0
    Mar 1, 2016
    Hi Dorke
    The fast clock is a product by Rail-Lynx. It is a normal digital clock that can be switched from real time to 'scale' time. So, you can enter whatever ratio you like so that a session with trains will make 24 hours (let's say) 4 hours. Y9u can therefore switch between real and scale at any time. You can also declare the time of sunrise and sunset. The PCB that is the fast clock also has on board 20 terminals noted as 'Buildings' that can be used to power on and off up to sixteen 12v lights housed in miniature buildings. Each of the 16 outputs are aligned with the 'fast clock' and each are programmed individually to switch on and off. For example, an output may be programmed thus.... 07:00 on - 09:00 off, 18:00 on - 10:30 off whilst another may be 08:00 on - 10:00 off, 17:30 on - 11:30 off. So, when the clock is switched to 'fast' the lights in the buildings come into play and switch on and off accordingly as directed by each terminals pre-programmed sequence. Btw..... I'm waiting on a response from the company that makes this but thought I'd try this forum in the meantime.
     
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