RailPro User Group
RailPro => RailPro Specific Help & Discussion => Topic started by: Dodgezilla04 on February 09, 2024, 06:19:12 PM
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Can anyone tell me the current rating of this module? Wanting to use it for my delton g scale rail truck since it's a small loco with one motor. I cannot find the ho info, only the g modules.
Thank you
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It should be the same as the LM-2 series of modules, 2 amp stall, 1 amp continuous.
If your railtruck will never MU (load share ) with another module you should also be able to use the LM-3S to drive a power transistor instead of driving the motor directly (same theory as how transistor throttles could pass high current without passing it through the potentiometer itself). Idea not tested of course.
- Tim
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It has no way of coupling to another loco or cars. I don't understand why I'd want to drive a lower transistor instead of the motor
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If the motor in the railtruck can draw more current than an LM-3S can provide (for example, 4 Amps), then you couldn't use an LM-3S to drive the motor directly. What can be done (in theory) is to use the LM-3 to drive a transistor designed for delivering a lot of power, or a pair of them in a configuration called a darlington pair and the transistor(s) then provides the power to the motor, easily supplying more than the LM-3 can deliver on it's own. Something very similar is already happening inside the LM, there is no way the microcontroller inside the LM can deliver 1A by itself.
Unfortunately I don't have a good drawing to post to explain it, nor do I have an explanation of how to handle forward and reverse. Our resident electronics guru would have been able to but sadly Alan has not been here for quite a long time for some reason.
- Tim
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Thank you. I'll just get the lm4sg, I know it'll supply enough current
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Note that the LM-3S is limited in the voltage not just amperage when trying to drive G scale locos.
If the railtruck requires more than 14-16 volts to get to the speed you require, then you need to move up to the LM4S.
If the G scale loco never requires the full 1 amp of the LM-3S limit and around 14 volts gets you up to full speed for that loco, go for it.