# AC POWER SUPPLY



## Madman (Jan 5, 2008)

Without going to a Lionel or American Flyer type transformer, where can I find a 0-20 volt, 5 AMP, power supply. At a resonable price, of course.


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## Greg Elmassian (Jan 3, 2008)

You want a variable AC supply from 0-20 VAC and 5 amps? 

Look for an old variac on the surplus market. 

What is the reason you don't want a Lionel or AF transformer? 

Variable AC power supplies are pretty rare. 

Regards, Greg


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## Madman (Jan 5, 2008)

Thanks Greg. No real reason other than possible cost savings. I don't know much about AC power supplies other than Lionel or American flyer transformers. I have been looking at them on Ebay. I already have a Lionel ZW that I use for powering my LGB switch motors, and anything else that requires AC power. I guess I need to learn alittle more about Variacs.


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## Greg Elmassian (Jan 3, 2008)

Do you really need a variable supply? That's where the cost is involved. Finding a 5 amp transformer is a piece of cake. 

Regards, Greg


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## Madman (Jan 5, 2008)

I just looked up Variacs. Pricey little buggers, arn't they.


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## Madman (Jan 5, 2008)

Actually I could probably use a fixed voltage. Somewhere in the range of 15-20 volts would work.


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## Greg Elmassian (Jan 3, 2008)

Much cheaper Dan... but keep on the lookout for some in surplus... I have a couple for those unusual situations. 

If you know the voltage you need, a fixed transformer is safer... what happens if a guest yanks a handle on your ZW? Could be bad. 

Regards, Greg


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## AppleYankee (Jan 3, 2008)

http://www.trcelectronics.com/24-volt-power-supply.shtml 

http://www.powersupplydepot.com/pro...t=16032+PS



Jan


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## toddalin (Jan 4, 2008)

Couldn't you just use an A/C transformer and a BIG rheostat? Something on the order of 50 ohms and 150+ watts seems like it should do it. These are available on the "bay" at reasonable cost.


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## krs (Feb 29, 2008)

Posted By toddalin on 07 Jul 2010 11:00 AM 
Couldn't you just use an A/C transformer and a BIG rheostat? Something on the order of 50 ohms and 150+ watts seems like it should do it. These are available on the "bay" at reasonable cost.


Not a good approach.
For one, the output voltage will vary with load and you also waste a lot of power.

AC supplies used to be a good way to go years ago when transformers were cheap and electronics expensive - for high power it's now the other way areound - high power transformers are expensive and switching supplies have become inexpensive commodity items.

For most applications, one doesn't really need AC.
If madman would post what he wants to use this supply/transformer, people could make a suggestion of what to buy.


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## Greg Elmassian (Jan 3, 2008)

Jan, he said AC power supply, not DC.... your first link is broken, the second to a DC supply. 

I agree with Knut... I think you can run switch machines on AC... 

Yep, better to have transformer at right voltage, and way cheaper... and if you did not want to pay cost of cheap lionel or AC transformer, then price is an issue, obviously. 

Dan, what exactly are you going to power? 

Regards, Greg


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## toddalin (Jan 4, 2008)

Posted By krs on 07 Jul 2010 11:31 AM 
Posted By toddalin on 07 Jul 2010 11:00 AM 
Couldn't you just use an A/C transformer and a BIG rheostat? Something on the order of 50 ohms and 150+ watts seems like it should do it. These are available on the "bay" at reasonable cost.


Not a good approach.
For one, the output voltage will vary with load and you also waste a lot of power.





Yeah sooo...

Big deal if the output voltage varies with the load. He has "operator feedback" to adjust the speed as necessary. And so what if he wastes power? Last I checked, it's still not all that expensive, especially when compared to a Lionel supply. This method has been used in other scales for many, many years, and still works. 

The necessary rheostat can be acquired on the "bay" for ~$10 and an adequate a/c transformer can be had for about the same.


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## krs (Feb 29, 2008)

Posted By toddalin on 07 Jul 2010 12:44 PM 
Posted By krs on 07 Jul 2010 11:31 AM 
Posted By toddalin on 07 Jul 2010 11:00 AM 
Couldn't you just use an A/C transformer and a BIG rheostat? Something on the order of 50 ohms and 150+ watts seems like it should do it. These are available on the "bay" at reasonable cost.


Not a good approach.
For one, the output voltage will vary with load and you also waste a lot of power.





Yeah sooo...

Big deal if the output voltage varies with the load. He has "operator feedback" to adjust the speed as necessary. And so what if he wastes power? Last I checked, it's still not all that expensive, especially when compared to a Lionel supply. This method has been used in other scales for many, many years, and still works. 

The necessary rheostat can be acquired on the "bay" for ~$10 and an adequate a/c transformer can be had for about the same.


Until we know what Dan wants to use the power supply for any further discussion or recommendation is useless.

He already said:


"Actually I could probably use a fixed voltage. Somewhere in the range of 15-20 volts would work."


...so why would you even suggest an AC transformer with a rheostat to vary the output voltage?

You can operate LGB switch machines with DC if that's what the application is - but I don't know.

Dan needs to tell us more about the intended use - I already said that in my earlier post.


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## Greg Elmassian (Jan 3, 2008)

Ummm.... if the voltage varied a lot, too low and whatever was using it might not operate. Too high and it could be damaged. 

I think that's a simple answer that's hard to find fault with. 

Todd, you said "to adjust speed".... I don't think we are talking locos here if a fixed voltage would work. It's most likely switch machines or some other accessory. 

I think that would make it clear that a fixed supply would be more appropriate, safer, less expensive, and yes, use less power. 

I think those are all legitimate reasons. 

Regards, Greg


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## toddalin (Jan 4, 2008)

Posted By Greg Elmassian on 07 Jul 2010 02:05 PM 

Todd, you said "to adjust speed".... I don't think we are talking locos here if a fixed voltage would work. It's most likely switch machines or some other accessory. 

I think that would make it clear that a fixed supply would be more appropriate, safer, less expensive, and yes, use less power. 

I think those are all legitimate reasons. 

Regards, Greg 

"Without going to a Lionel or American Flyer type transformer, where can I find a 0-20 volt, 5 AMP, power supply. At a resonable price, of course." 

Seems pretty obvious to me. Use of a "fixed" voltage is merely to save $$$.


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## krs (Feb 29, 2008)

Todd - 

If Dan is really looking for a power pack to run Lionel or American Flyer Trains, he might as well buy the proper 5 Amp Lionel power pack that sells for about $50.- 
http://compare.ebay.com/like/280513007830?ltyp=AllFixedPriceItemTypes&var=sbar 

A 5 amp 24-volt transformer by itself from the surplus place is $30.- 
http://www.allelectronics.com/make-a-store/item/TX-245/24-V.C.T.-5-AMP-POWER-TRANSFORMER//1.html 

and then you have to add a case, AC cable, fuse, connector strip for the output, a rheostat, a control knob.............and don't you need a higher voltage pulse to reverse direction on these AC powered trains? 
That would cost you more in the end and you have a 'butchered together' solution. 

A variac I think is out completely. 
Variacs are used to adjust the line voltage, so their output is typically 0 to 140 volts or so. 
 To get some goood control range, you would need to connect a 115 volt to 20 volt step-down transformer at the output of the variac. 

I think $50.- for a 5amp model train supply is more than reasonable - you're not going to find a much cheaper solution.


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## toddalin (Jan 4, 2008)

Posted By krs on 07 Jul 2010 04:13 PM 
Todd - 

If Dan is really looking for a power pack to run Lionel or American Flyer Trains, he might as well buy the proper 5 Amp Lionel power pack that sells for about $50.- 
http://compare.ebay.com/like/280513007830?ltyp=AllFixedPriceItemTypes&var=sbar 

A 5 amp 24-volt transformer by itself from the surplus place is $30.- 
http://www.allelectronics.com/make-a-store/item/TX-245/24-V.C.T.-5-AMP-POWER-TRANSFORMER//1.html 

and then you have to add a case, AC cable, fuse, connector strip for the output, a rheostat, a control knob.............and don't you need a higher voltage pulse to reverse direction on these AC powered trains? 
That would cost you more in the end and you have a 'butchered together' solution. 

A variac I think is out completely. 
Variacs are used to adjust the line voltage, so their output is typically 0 to 140 volts or so. 
To get some goood control range, you would need to connect a 115 volt to 20 volt step-down transformer at the output of the variac. 

I think $50.- for a 5amp model train supply is more than reasonable - you're not going to find a much cheaper solution. 



You guys have him already buying the transformer so he'll need the case, etc. anyway.










So, I'm taking a difference of ~$10 for the rheostat. Anyway, you can do better than Allelectronics. How about 24 vac at 10 amps for


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## krs (Feb 29, 2008)

Bottom line is that we don't even know what the application is that Dan had in mind for this unit. 

My point was simply that buying a transformer, a case and all the other bits and pieces will cost more in the end than just getting a proper train transformer if in fact that's the purpose Dan had in mind. 

That particular transformer from MPJA (and I'm sure the AllElectronic one is not any better) has a high output impedance and poor regulation - you can tell just from the size of the unit. 
It's suitable for a DC power supply where the inadequacies of this transformer can be compensated with the solid state regulator, but as a straight AC ransformer the output will be all over the map depending on load. 
I bought a couple of these inexpensive types years ago and was just amazed at the variation in output voltage over their 0 to 10 amp range. 

If you want a good transformer with good regulation you should really consider getting a torroid.


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## Madman (Jan 5, 2008)

Posted By toddalin on 07 Jul 2010 04:34 PM 
Posted By krs on 07 Jul 2010 04:13 PM 
Todd - 

If Dan is really looking for a power pack to run Lionel or American Flyer Trains, he might as well buy the proper 5 Amp Lionel power pack that sells for about $50.- 
http://compare.ebay.com/like/280513007830?ltyp=AllFixedPriceItemTypes&var=sbar 

A 5 amp 24-volt transformer by itself from the surplus place is $30.- 
http://www.allelectronics.com/make-a-store/item/TX-245/24-V.C.T.-5-AMP-POWER-TRANSFORMER//1.html 

and then you have to add a case, AC cable, fuse, connector strip for the output, a rheostat, a control knob.............and don't you need a higher voltage pulse to reverse direction on these AC powered trains? 
That would cost you more in the end and you have a 'butchered together' solution. 

A variac I think is out completely. 
Variacs are used to adjust the line voltage, so their output is typically 0 to 140 volts or so. 
To get some good control range, you would need to connect a 115 volt to 20 volt step-down transformer at the output of the variac. 

I think $50.- for a 5amp model train supply is more than reasonable - you're not going to find a much cheaper solution. 



You guys have him already buying the transformer so he'll need the case, etc. anyway.










So, I'm taking a difference of ~$10 for the rheostat. Anyway, you can do better than Allelectronics. How about 24 vac at 10 amps for


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## AppleYankee (Jan 3, 2008)

Dan, 

I used the quick reply and didn't notice the second link didn't paste correctly. 

The link to the AC & DC Power Supplies 

Jan


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## Greg Elmassian (Jan 3, 2008)

That link still comes up on the DC power supply, but if you click "transformers", on the left side, second from the bottom, you will see transformers and variacs. 

So, the entire smorgasbord is available! 

Regards, Greg


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