question about motors

Discussion in 'FAQs' started by nachoman, Mar 9, 2005.

  1. nachoman

    nachoman Guest

    What determines what voltage a DC motor can operate at without burning up? I just took apart a broken portable CD player and saved two motors. They look like mashima motors, and one may be perfect for a small N scale loco. The cd player ran off of two AAs- but should I take that to mean the motors could not handle 12v?

    kevin
  2. ezdays

    ezdays Out AZ way

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    Kevin,

    The manufacturer determines what the maximum voltage a motor can take. In your case, I wouldn't try more than 3 volts DC. Any more than that will cause it to burn up. If you knew how much current the motor used at that voltage, you could add a series resistor to act as a voltage divider, but that is tricky and may require a high wattage resistor that would take up as much space as the motor does.
  3. Pitchwife

    Pitchwife Dreamer

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    Kevin is right. Applying too much voltage to a motor will burn it up. Another thing you could do is buy/build a voltage regulator that would supply the propper voltage to the track. If you like I could let you know of a few sites that feature simple electronic projects that could guide you through the process.
  4. ezdays

    ezdays Out AZ way

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    Clark,

    A voltage regulator would also do the job, but I'm thinking about the space it, or a series dropping resistor would take up. Something that maybe would be easier would be a zener diode, but again, where do you put the components? I think Kevin would still be better off getting a 12 volt motor rather than trying to regulate the input. Then on the other hand, he may just want to play around with our suggestions, sounds like a fun thing to try. :) :)
  5. Fred_M

    Fred_M Guest

    It would work fine with a DCC decoder programmed correctly in a locomotive. Seems the obvious solution for using it in a locomotive, don't it?
  6. ezdays

    ezdays Out AZ way

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    No, not really. I could do the same thing with my programmable DC power pack too, limiting full throttle to 3 volts, but who wants to keep track that way when all others run fine at full output? Make a mistake in either case and it's smoke city.. :eek:
  7. Fred_M

    Fred_M Guest

    You only need to program a DCC module once, there's really no need to re-program it again, so what's there to keep track of?
  8. nachoman

    nachoman Guest

    thanks for the replies, everyone. These motors were "free" in the sense that they were salvage from something I was going to throw awa. I guess I will save then for some project where I am dealing with 3v or less.

    kevin
  9. ezdays

    ezdays Out AZ way

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    well, Fred, I've stated before that I'm not into DCC, so I can't answer for sure, but where is the memory for the DCC module, in the module or in the programmer? Is the memory non-volitile in that once programmed, it remains forever, even after a power failure or shut down? I'm not challanging you, just asking... :) :)

    The bottom line though is, if I needed to buy a DCC system because I had one motor to control at 3 volts and all the others ran fine at full voltage, I think I'd opt to change the motor rather than change to a whole new system of control. :wave:
  10. Ray Marinaccio

    Ray Marinaccio Active Member

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    I have been experimenting with the use of lower voltage motors for repowering locomotives.
    In some cases the voltage reduction circuit is larger than the motor.
    If the motor draws a relatively low current diodes, zener diodes and resistors will work.
    When you have a motor that draws a bit more current you start having problems with heating of these components.
    I did come up with a voltage following circuit that uses a pair of transistors and some resisters that works, but cramming it into an N scale loco might be a challenge.
    I have some motor control chips on some old VCR boards I would like to experiment with someday.
  11. Fred_M

    Fred_M Guest

    The memory in DCC is on the modules and they can be stored even off the layout for years without reprogramming Don. They will also run on your buddies layout without reprogramming. One would set start voltage to near zero, max to about 3 or 4 volts, and then play with the steps if desired. Once set it would be done.


    Ray, have you tried a 3 volt motor to see if it has enough torque to really be of use as a train motor?. Inquiring minds want to know. :thumb: :) Fred
  12. ezdays

    ezdays Out AZ way

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    Fred,

    That's cool. I guess I need to spend more time down in the DCC section to see what's going on. :) :) I wonder what they use for memory and how much can you store in a remote module...

    And you got a point there about torque. I would think a motor out of a CD player was designed for high RPM's rather than high torque.
  13. Ray Marinaccio

    Ray Marinaccio Active Member

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    Fred,
    Most of the 3 V motors I have used don't have as much torque as a 12V motor and require additional gear reduction. (which I like to do anyway)
    There's a couple of photos in this link of one I put in a Tyco diesel truck.
    http://www.the-gauge.com/showthread.php?t=6333

    I have found a lot of 6V motors from CD drives that work well with only a constant intensity light circuit in series to reduce the voltage.
  14. Fred_M

    Fred_M Guest

    LOL Ray, that was a long time ago Friend. :) Welcome to the gauge LOL. Did you ever get around to building that PWM module? Another thought that just came to me is dirty track. At those low voltages track oxidation, dirty wheel, and such would become an even bigger problem. Fred
  15. Ray Marinaccio

    Ray Marinaccio Active Member

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    I never did build the onboard PWM module but did sketch out a few schematics. I had a momentum feature incorporated into one of them. That's one of those projects I need to get back to.
    I think you have a point about the low voltage and dirty track.
    If you used a pulse throttle that pulsed 12-18 volt pulses, would that overcome the problem?
  16. ezdays

    ezdays Out AZ way

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    Ray,

    In my opinion, I doubt that the pulsed throttle would make that much difference. Yeah, a higher voltage would have the tendency to break through the oxidation better then the 3 volt source, but remember, to achieve the average lower voltage, the pulses are really short and far between and may not be there long enough to make a big difference. That is my opinion and I'd like to hear someone else's thoery, or facts on this. :)

    One thing about using a pulsed throttle, as you know, the peak voltage remains constant and the pulse width varies to obtain the "average" DC equivilant. I'm not sure how long a 3 volt motor would handle those 18 volt spikes. One thing I do know is that you cannot run a 3 volt incandecent lamp off of the pulsed output, even when it's set for 3 volts. I was checking a light bulb the other day and was too lazy to get out my vriable DC supply and so I set my throttle output for 3 volts and tested the bulb. Well, it was good, yeah, for about 10 micorseconds it was, since what it really saw was the peak voltage and not the average. Hmm, little flashlight bulb lit up thw whole room it did.... :eek: :eek: :)
  17. Pitchwife

    Pitchwife Dreamer

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    Hi guys. Been away for awhile and kinda lost track of this thread. Re onboard voltage regulatore, I think that this would be the best solution to overcoming the dirty track problem. As long as the voltage that reaches it remains above the 3v for operation, and if your tracks arre that dirty you have other issues to worry about :) , it will run. Re size of componants. the motor isn't going to be pulling that much currrent so a zener diode and a few 1/4 or 1/8 watt resistors shouldn't be a deterant. Also there are single chip voltage regulators which should eliminate that problem.