??? Adding a handheld throttle to an exsiting throttle

Discussion in 'FAQs' started by MinnMonkey, Sep 14, 2007.

  1. MinnMonkey

    MinnMonkey Member

    I am thinking of trying to build a handheld throttle for my layout and looking for some advice. I am running DC.

    I have my current throttle/powerpak running to the track. I am wondering, if I could put a secondary throttle between the primary throttle and the track, ie:

    AC Wall -> DC Power Pack / Throttle -> Handheld Throttle -> Block Selector control panel -> Track

    On the handheld throttle there would be a DPDT switch to control the direction of the trains, and either a rheostat or a potentiometer to control the speed.

    My thought would be if I want to use the layout mounted throttle, I would crank the handheld up to 100% and use the throttle on the power pack, and if I wanted to use the hand held throttle, I would crank the power pack to 100% and control power flow with the hand held

    Any thoughts, concerns or suggestions to this madness?
  2. 60103

    60103 Pooh Bah

    It can be done that way. You have to remember to turn the one you're not using all the way up.

    I prefer to have a fully separate unit and run it from the power pack's AC terminals, or from a separate transformer.
  3. steamhead

    steamhead Active Member

    If you follow David's suggestion of using the pack's AC terminals, you'll have to use a rectifier to get DC out of it.
  4. MinnMonkey

    MinnMonkey Member

    What would you recommend using as the throttle itself, a rheostat, a potentiometer or something completely different
  5. 60103

    60103 Pooh Bah

    If you use my version, you need a rheostat -- I forget the resistance, but it needs a big capacity for heat dissipation. The basic would be bridge rectifier, rheostat, and reversing switch. I don't think a potentiometer has the capacity.
    More useful would be a transistor throttle; I have a couple of hand sized ones. You can get a simple one or have extra effects. (Search for it and there should be some wiring diagrams and references. Also SCR throttles)
  6. doctorwayne

    doctorwayne Active Member

    I have a couple of SCR throttles that run off the AC side of the power pack (or even a separate transformer - I have used one from an old oil furnace that worked well). They offer excellent low speed control and one of them also has a 5-position brake that allows you to set the throttle speed, then control the train solely with the brake - with a little practice, you can get very smooth and prototypical acceleration and braking. The downside to both of these throttles is that they don't put out enough power to run heavy, doubleheaded trains on steep grades. For that, I use a MRC Controlmaster 20, with its own walk-around throttle - I've run over a dozen locos at once with this, as it's got loads of power, but the throttle response is much coarser than with the SCRs: it's like using a sledgehammer to swat a fly.

  7. ezdays

    ezdays Out AZ way

    It depends on what you're using for a power pack. I've got a couple of MRC Tech 4's that have an external throttle connector. If you have one of those, I have the schematic to build a plug-in throttle for one. If not, I might suggest you use a DC source that has no control or at full power, then build a couple of regulator/controllers, one mounted on a panel, the other for a hand-held remote and switch between the two. I can probably provide you with a DC to DC controllable regulator schematic as well or I'm sure you can find plenty of them if you search the web.
  8. MinnMonkey

    MinnMonkey Member

    This is exactly what I am thinking of doing. Could I get a schematic from you?

  9. ezdays

    ezdays Out AZ way

    I'll put something together and get back to you. It might be a day or two, I'm kinda busy right now, but I won't forget.:wave:
  10. JR&Son

    JR&Son Member

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