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Hello fellow railheads, I am stuck in a wiring problem. I have 3 pre war HO scale American Flyer Hudson Engines I am trying to convert from the previous AC power that they used to DC power for use on my layout. I known I can somehow bypass the eunit in these engines with a diode or rectifier? Anyone already done this with any of the S scale American FLyers that also used AC power? Could someone give my some advice or instruction on how to do this, I have searched all over you tube, and the main train/parts dealers and can not find detailed instructions. my problem is there are 4 points of contact on the engine from the tender and only two out puts from the full bridge rectifier. doubling up the leeds does not work and single leads do not work I need help please
Thanks
Jim
Hello fellow railheads, I am stuck in a wiring problem. I have 3 pre war HO scale American Flyer Hudson Engines I am trying to convert from the previous AC power that they used to DC power for use on my layout. I known I can somehow bypass the eunit in these engines with a diode or rectifier? Anyone already done this with any of the S scale American FLyers that also used AC power? Could someone give my some advice or instruction on how to do this, I have searched all over you tube, and the main train/parts dealers and can not find detailed instructions. my problem is there are 4 points of contact on the engine from the tender and only two out puts from the full bridge rectifier. doubling up the leeds does not work and single leads do not work I need help please
Thanks
Jim
You have it backwards, unless you worded that wrong.
A rectifier converts AC from the supply to DC at the load end. If you add a bridge to an AC motor to make the supply appear as DC, it won't help a bit. You would simply be trying to convert the DC track power to DC, which it already is.
Most AC motors will work on DC. The type of AC motor that will not work on DC would be an induction type or style without a commutator and brushes. If the motor has both field and armature magnetics supplied by windings the motor should run on DC or AC. If it relies on induction, which means it also would not have brushes, it will only run on AC and the conversion would require complicated electronics that convert DC to AC.
rectifiers and stuff like that do not convert the load. They alter the power source, NOT the load. The load is what the load is. The motor is the load. If the motor only runs on AC, you need to convert the DC supply to AC. This requires a chopper or inverter or DC to AC converter of some type. This can be done at the motor or anywhere between the load and supply.
If the motor runs only on DC and you have an AC supply, then a rectifier system will work. This can be done anywhere between the motor and the power supply.
But most old small cheap AC motors were brush type motors that run either on AC or DC.
Tom,
Thanks for the information, the motor is indeed a coil magnetic field motor with brushes. When AC power is applied it will run, when DC power is applied it just shakes and gets hot? I saw Model RR magazine where a person had converted their AC powered American flyers to run on DC power? They mentioned to use a Rectifier but did not explain the wiring. I will try with just adjusting the eunit wiring to see if I can get the filed correct around the coil?
Thanks Jim
Oh and one more thought, my purpose is to try and eliminate the eunits all together and just be able to change direction on the engine by reversing the polarity of the DC current, as a more modern engine would run on
Oh and one more thought, my purpose is to try and eliminate the eunits all together and just be able to change direction on the engine by reversing the polarity of the DC current, as a more modern engine would run on
An electric-field-coil electric-armature motor can only be reversed by reversing ONE of the two windings. If both are reversed, then the motor runs the same direction.
To solve this you might be able to run one winding from the DC output of the bridge so that winding never reverses, and the other winding from the AC input of the bridge which is also common with the track feed.
This all hinges on the motor being capable of handling DC, and having enough back EMF or impedance to not draw excessive current on DC.
^^ so you'd put a rectifier between pickups and, let's say, the field magnet, then wire the brushes directly to the pickups.
If the motor won't run even then on DC, you might (and my knowledge here is limited) be able to fudge it until it does. I don't imagine you'd want to rewind the coils though.
Some motors might work better with the field to the pickups and DC out of the bridge to the brushes, and some might work the other way.
If the windings are in series in the original state then it is still possible to series them. One lead of the AC input of the bridge would go to a pickup. One motor winding across the DC output of the bridge. The other motor winding then in series between the bridge's remaining AC terminal and the other pickup point.
This way one winding is in series with the other, but one is fed a constant polarity.
If the motor won't run even then on DC, you might (and my knowledge here is limited) be able to fudge it until it does. I don't imagine you'd want to rewind the coils though.
Thank you all for the advice, I will try the different combinations and see what I cam up with. Eric I would have remotored but my hope is to keep this train as original as I can while still being able to run it on an HO track with other Ho trains, unfortunately it would be easy enough to just power the track with AC using one of my AF power supplies but then the rest of my DCC stuff would be done :-( Tom thanks for the time, I will try the singel brush and single coil contact to see if that will work.
Jim
It's really odd how the AC motor won't run on DC. Usually from what I've seen, AC motors with brushes will run on DC, but would need a voltage spike to reverse direction.
The above converts 12v to 120 V and the transformer helps to step-up the voltage. So in theory, if one doesn't use transformer, it will act as a basic DC to AC converter.
The above converts 12v to 120 V and the transformer helps to step-up the voltage. So in theory, if one doesn't use transformer, it will act as a basic DC to AC converter.
Most brush type motors with electromagnet fields run just fine from AC or DC.
Your top link is busted. As for the bottom link, that inverter always needs a transformer. It won't run without one. The transformer center tapped winding is what inverts phase for the feedback.
If the motor won't run on DC, which most would run OK on DC, then he probably would want a solid state bridge chopper as a dc to ac conversion. It would not require a transformer and would be much smaller and lighter.
Years ago while down in Mobile, a friend of mine converted a AC Max Gray O-scale shay to work on DC by simply installing a solid state bridge rectifier. Should be a simple process. I know others have suggested a BR, so I would at least look into it.
Years ago while down in Mobile, a friend of mine converted a AC Max Gray O-scale shay to work on DC by simply installing a solid state bridge rectifier. Should be a simple process. I know others have suggested a BR, so I would at least look into it.
If you want the motor to behave like a DC permanent magnet motor so reversing DC polarity reverses rotation, a bridge rectifier is required.
There are only four possible ways to wire the bridge, and I'd be happy to draw those four ways if that information is not available elsewhere. Which way works best would depend entirely on the motor's characteristics and the available DC voltage.
