Servo control manufacture choices

videobruce Sep 14, 2021

  1. videobruce

    videobruce TrainBoard Member

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    I have a large number of turnouts to control and after doing some immense research I find there seems to be three current major choices to control SG90 type servos for turnouts (if there is any others please name them);
    Arduino
    MegaPoints
    Pololu

    Arduino & Pololu both use confusing, very compliacted 'scripts' that basically make one learn programming language which should be unnecessary just to move a set of points normal or reverse. (n)

    That leaves Megapoints for the UK. So my questions are to anyone that is knowledgeable about these;

    1. Are they available in the US from a US dealer or is the only source the UK?
    2. If only the UK, are they available thru a UK dealer instead of going direct thru the manufacture??
    3. What are your experiences with these? Good and bad?
    4. Other then cost, any negatives?

    The website is here;
    https://megapointscontrollers.co.uk/product/servo-controller-12/?v=79cba1185463
     
    Last edited: Sep 14, 2021
  2. papahnash

    papahnash TrainBoard Member

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    Turnout servos have been done for a while with Arduino. There are examples out there like this one.

     
  3. videobruce

    videobruce TrainBoard Member

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    Using scripts............. :rolleyes:
     
  4. chinapig

    chinapig TrainBoard Member

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    There is an option you haven't mentioned which is DCCNext. These are Arduino based decoders that are programmable on your pc through a series of menu-type questions. There's no programming involved but there is a bit of a learning process to get the procedure up and running.

    https://www.arcomora.com/dccnext/

    These are available as kits or pre-assembled. The kit costs about €16 and will basically control 8 servos and also switch the frog polarity. I've used about a dozen of them.

    I'm sorry, I have no experience with Megapoints.

    Cheers, Ted
     
  5. Mike 354

    Mike 354 New Member

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    I am using the Digikeijs DR4024 4 channel Servodecoder with 4 extra switching outputs. They have some cool built in modes for crossing gates and signals as well as switching servos.
    You need a command station or throttle that can address 9999 to program it.
     
  6. videobruce

    videobruce TrainBoard Member

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    I run DC, not DCC.

    I did find out these are only thru the manufacture in the UK. They ship to the US via 'Royal Mail'. By adding items to your 'cart' and supping your state & zip code the rate will be shown. It seems to be reasonable.
     
  7. tjdreams

    tjdreams TrainBoard Member

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  8. videobruce

    videobruce TrainBoard Member

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    No, but I will look into it.
     
  9. CSX Robert

    CSX Robert TrainBoard Member

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    I don't know if you understand how servos work or not, but unlike motors or solenoids they are controlled by sending a series of pulses instead of just a voltage. Just an FYI so you understand why they are a little more complicated to control.

    Tam Valley Depot and Team Digital both used to sell servo controllers for turnout control, but neither one does anymore. You might still be able to find some of their products.

    Servo control is ratiometric, meaning it's not just on or off, or left or right; you tell it how far from the end of it's travel. With turnout control, however, you really only need two points, left and right. One easy way to accomplish this follows:

    Start with two servo testers like these.
    Set one for your left limit and one for your right limit.
    Connect the servos to +5 volts and ground. Wire the signal input to each servo to a SPDT toggle to switch it between the signal outputs of the two servo controllers.

    With this method you don't have the ability to set the movement limits of the servos individually, but you really shouldn't need to with turnout control.
     
    BigJake likes this.
  10. videobruce

    videobruce TrainBoard Member

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    Yes I do and I'm glad you added "a little more". There is nothing "little" about those scripts! :rolleyes:
    From actually testing one of these w/ a Tam Valley controller, two pulse widths; one long & one short, 0 & 90 degrees travel for the default non tweaked action was the norm. I don't consider that complicated like those endless scripts.
     
    Last edited: Sep 16, 2021 at 5:55 PM
    BigJake likes this.
  11. Sumner

    Sumner TrainBoard Member

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    Dave Bodnar introduced those $1.50 controllers as servo controllers a while back and I took his idea a litter further.

    [​IMG]


    You solder two wires on along with another very inexpensive pot and you can control the amount of throw in each direction. More on how to do that ( HERE ).

    Here is a video showing how to use the controller...



    Using a switch setup..

    [​IMG]

    [​IMG]

    ... like above you can control the controller and servo and throw it in either direction using the single controller along with controlling the amount it throws. Can't control the speed but I'll bet something could be added to the cheap controller that would also do that.

    [​IMG]

    You can put everything you need to throw the turnout (shown above) for under $8.00. I have a lot more info on all of it ( HERE ). The soldering required is not complicated or hard and one of the pluses of doing this is servo control without using an Arduino or other expensive controller.

    Sumner
     
  12. videobruce

    videobruce TrainBoard Member

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    That "servo controller" you show is the one from the previous link w/o the cover??

    My panel already has push button switches (not toggles) for the turnout controls and holes for a single bi-colored LED. With this setup, I would still have to use toggles??

    And if one doesn't know anyone that has a 3d printer??


    Oh, I contacted that Berrett Hill but I haven't received a reply yet.
     
    Last edited: Sep 17, 2021 at 8:44 AM
  13. Sumner

    Sumner TrainBoard Member

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    Yes, and the link to the all the info is ( HERE ).

    Sorry but as it is wired now you need both the toggle and push button switches. Some servo controllers have the servos powered all the time. The circuit only powers the controller and servo when the momentary push button is pushed.
    [​IMG]
    I haven't tried it but one could probably remove the momentary switch and use only the toggle (thus needing only one hole for that). Run the red wire from the power supply to the resistor. Also run the red wire that was on the momentary switch that goes to the controller through a switch to the power supply.

    The controller and servo would then receive power anytime the power supply switch was thrown. You would throw that power switch at the beginning of an operating session. The power supply would have to be rated so it had enough power for all the controllers and servos attached as they would all be receiving power at all times. I've never tried powering a controller and servo continuously but believe some do (maybe research that). I will have a number connected to the $15 power supply I have but since only one is requiring power at a time (when the push button is pushed) there isn't much demand on the power supply.

    You could also use your bi-colored LED and wire it to the toggle switch similar to how the two LEDs are wired above. Doing the above you could use the two holes you now have to handle throwing the turnout and for the bi-colored LED. Before ordering parts though I would research having the controller and servo powered for extended times when the layout is being used. I'll bet someone else on here could comment on that situation. Also sizing the power supply to the number of servos being used would be necessary. If you would like another diagram like above showing the revised wiring let me know.

    The wiring for the switch and LEDS either in the control box or on a control panel is not complicated and neither is the wiring on the servo controller. You can use cheap readily available servo extension cables between the toggle switch/LED controls to the servo controller and between the servo controller and the servo. No Arduino or computer knowledge is required.

    I know of someone who is printing some of the buildings and other items I've designed and selling them. I'll see if he might be interested in also printing some of these items (switch boxes, box tops with route, servo controller mount and servo mount) and selling them through his eBay store. Also my print files are on thingiverse.com ( HERE ) so are available for anyone to print and use or sell. I'd just like to get credit if someone is doing that and a link to my site on how to use them.

    This might be incentive to get a 3D printer and pay for it with money saved :sneaky:

    Sumner
     
    Last edited: Sep 17, 2021 at 7:04 PM
  14. videobruce

    videobruce TrainBoard Member

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    Last edited: Sep 17, 2021 at 6:16 PM

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