# Power supply: taste great/less filling.



## Hoganflagle (Sep 21, 2019)

I know I'm a trouble maker but it is the only way I learn. 

I read that a lot of folks are turning to laptop adapters for power supplies, so I went to the thrift and got one. The one I found has an output rated at 19.5 VDC and has 6.5 VA. Why would that be a better choice than a DC2 power supply which is rated at 20 VDC and 12 VA?


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## Milton Fox Racing (May 27, 2014)

In your reading did you learn why they are using them? Or even recommending them? I would imagine that they are cheap and plentiful are the only two reasons provided. But it would be interesting to hear any other reasons they give.

Your are starting to go beyound my pay grade in the technical aspects and I am sure Rich will be able to explain all of those technical aspects or refer you to an article aleady prepared for it. 

But in general - it really depends on what you want your power source to provide for your track needs and whether or not either of them will meet that desire. Most likely exceed the actual demand.

So do you want your cars to go as fast as they can? Or as fast as the track design allows?

You can of course works backwards from having to much power, too. Which would be as fast as the chosen power pack allows.


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## Hoganflagle (Sep 21, 2019)

I just want sufficient power to move the cars around 39 feet of older track. Not doing any competition anything, just home use.


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## Milton Fox Racing (May 27, 2014)

Then the one you already bought will be more than adequate. :cheers2:

Have you figured out how you are going to connect it to the your terminal track piece yet? :lurk5:


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## Rich Dumas (Sep 3, 2008)

Here is an article on power supplies: https://drive.google.com/file/d/1r_mey6LXg4kmp6sX4U3lU-fDA72pXhfj/view?usp=sharing


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## Milton Fox Racing (May 27, 2014)

The above article addresses lap top power supply devices at the bottom of page 4 and then goes into how you can regulate (connect) it to the track. All of which may eat up the savings cost from the cheaper source that was (is) probably built into the more expensive (power source) device you asked about originally. And was more likely a plug (connect) and play set up.

:cheers2:


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## Hoganflagle (Sep 21, 2019)

I fear I have been wasting everyone's time but greatly appreciate your patience with me and all the helpful responses.

I hooked up a DC1 to one lane on one terminal section to see where my bad spots were. Boy did I have a bunch most of them were fixed by dragging a razor blade on the track but I have a few pieces I will replace. 

With only one terminal section connected I did not see any noticeable power drop anywhere but will still connect the 2nd anyway. The DC1 on one lane was more than enough as I discovered I need to put guardrails up on most of my curves.

Something I did notice. I am having some issues with some cheap slot car guide pins I bought and will need to go find some quality ones.


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## Rich Dumas (Sep 3, 2008)

What is a DC 2 power supply or a DC 1 for that matter? My article goes into great detail, but it is best to use a regulated power supply if you want to power more than one lane. Laptop power supplies are regulated. Both of the power supplies that you mentioned have very low outputs, about the same as a set type supply, I would not consider them to be an upgrade. 
It sounds to me like your track rails are corroded, you will have to remove the corrosion or no power supply will be an improvement. If the track rails are visibly rusted you might be wasting your time trying to clean it. Once steel has gotten rusty it is much more prone to further corrosion.


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## Hoganflagle (Sep 21, 2019)

*My bad.*



Rich Dumas said:


> What is a DC 2 power supply or a DC 1 for that matter? My article goes into great detail, but it is best to use a regulated power supply if you want to power more than one lane. Laptop power supplies are regulated. Both of the power supplies that you mentioned have very low outputs, about the same as a set type supply, I would not consider them to be an upgrade.
> It sounds to me like your track rails are corroded, you will have to remove the corrosion or no power supply will be an improvement. If the track rails are visibly rusted you might be wasting your time trying to clean it. Once steel has gotten rusty it is much more prone to further corrosion.


DC-1 is the model number of the original Aurora Model Motoring power supply. On the Modelmotorist.com web site it's output is listed at 18 VDC 12VA. At the posts my DC-1 is putting out 18 VDC. There is also an Aurora Model Motoring power supply shown there that is a model DC-2 that has an output of 20 VDC and 12VA. One definite drawback with these power supplies are that they do hum. I accidently left one on overnight and the next morning it wasn't humming it was buzzing like one of these electric etchers. Opened it up to see if there was any way to quiet it down but there wasn't so now I use it in the garage as a power source when working on track pieces or cars.









I will have a dedicated power supply for each lane. One power supply will be a train power supply that I can step back the power so that my granddaughter won't be wiping out on each curve.

I am waiting on some track clips to come in so I can get a good compression on the joints. Once they arrive I will be doing sections at a time and testing each section with power and a car looking for any hesitation. This will give me a better look at any unsalvageable pieces. Some of the tracks initially had a light rust on them that immediately came off with a couple swipes of the sanding block but I suspect that they may have dark spots which would be signal blocking cancer. 

I know in the HO train set we had there was a flat car that had a belly stone for cleaning the track. Too bad there isn't a Tjet or AFX version:smile2:


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## Milton Fox Racing (May 27, 2014)

Not a waste of time and I encourage others to be helpful to new members as much as they can. Our search function doesnt work to well here and finding things is often hard to do.

If you do need to search for something here, I find it works better to googel hobbytalk and what you are searching for in your own search browser as it will usually give you a more direct hit than our own tired little searcher electrons can.


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## Rich Dumas (Sep 3, 2008)

Years ago I tested a Model Motoring 20 volt 12 VA power supply, by the way VA is the same as watts. With no load applied it put out 19 volts. I connected a series of light bulbs to put a steady load on the power supply and measured both the amps and volts. With a 0.25 amp load the voltage dropped to 16 volts and with a 0.55 amp load it was only 14.2 volts. A Tyco car with a 6 ohm armature will pull 0.5 amps when it is accelerating and 0.25 amps when it reaches full speed, so you can see that this sort of power supply is marginal even if you are running a single car. Any power supply that is not regulated, even a much larger one, will have a voltage drop when a load is applied. 
I realize that in your case having a steady voltage is not critical and if you are using a separate power supply for each lane they do not necessarily have to be matched.


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## Patrick32218 (Nov 14, 2019)

Still learning and experimenting... What are your thoughts on using something like this with a the tracks wall wart or laptop power supply https://rover.ebay.com/rover/0/0/0?mpre=https://www.ebay.com/ulk/itm/254395516567

I am running a home 4 lane Tommy track which is working out just fine for me and the kids... But before I dive deeper into the viper and Wizard high performance cars to satisfy my enthusiasts sensibilities...I really need to justify to my self and budget how farther I can take this hobby ?. I don't have the benefit of a local club to ask these questions... You guys are my "local club" ?

Thanks in advance, and happy 2020


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## Rich Dumas (Sep 3, 2008)

The limiting factor would still be your set type power supply, that has marginal power at best. If you had a large unregulated power supply and wanted to add regulation as well as variable voltage that unit would be useful. The same would go for an undersized laptop power supply. If you take the VA rating and divide that by the rated output voltage that will tell you how many amps would be available. For a 90 watt 20 volt power supply that would be 5 amps, plenty of power for a 4 lane track and most HO slot cars.


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## Rolls (Jan 1, 2010)

After a lot of hunting, I ended up going with the Pyramid 5A 30V supply, which has worked great in my 4-lane application for years. Sadly, some googling shows this unit is not easy to find anymore, and is double the $65 I paid last decade. But if you happen upon one used and working at a good price it might have years of trouble-free service left in it.


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## alpink (Aug 22, 2010)

https://www.ebay.com/itm/30V-10A-Ad...a=0&pg=2047675&_trksid=p2047675.c100005.m1851



https://www.ebay.com/itm/30V-5A-US-...a=0&pg=2047675&_trksid=p2047675.c100005.m1851

https://www.ebay.com/itm/30V-10A-Ad...a=0&pg=2047675&_trksid=p2047675.c100005.m1851

https://www.ebay.com/itm/30V-10A-Di...380554?hash=item4d9e9a17ca:g:gKwAAOSw1OBeAwHZ

these are similar (30 volt 10 amp) power supplies that I use.
a little higher priced than when I bought them, but maybe the prices will come down again once the tariffs are ended.
these work very well


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## rbrunne1 (Sep 22, 2007)

alpink said:


> https://www.ebay.com/itm/30V-10A-Ad...a=0&pg=2047675&_trksid=p2047675.c100005.m1851
> 
> 
> 
> ...


These work great! I used one on a previous layout. Nice stable power supplies. Plenty of power to run "stock" class cars.


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## Patrick32218 (Nov 14, 2019)

Plenty of power to run "stock" class cars... Thanks,I've been eyeing these as well ... But would 10 amps be enough to push 3.5 ohm or lower arm with higher levels of magnets (closer to there potentials) I am making assumptions here ?


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## Rich Dumas (Sep 3, 2008)

Recently I ran a BSRT G3 Modified car with a 3 ohm armature on my dyno. The dyno puts a mechanical drag on the car to simulate what happens on the track. At 18 volts the car pulled a steady 0.5 amps. On the track that would be what the car would draw once it hit top speed. Based on the actual on track measurements that I have taken of a car with a 6 ohm armature I would expect that the 3 ohm car would pull 1 amp when it was accelerating off of a corner. You could run four 3 ohm cars to their full potential with a 10 amp power supply, that would be skimpy with Restricted Open type cars however.


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## Patrick32218 (Nov 14, 2019)

@Rich Dumas

As always thank you ? for your detailed and succinct response. I am learning a lot from these forums.

What is a "Restricted Open type car"

Before I electrocute myself... I do have a few power supplies I pulled from retired servers. A single unit is 12v 45 amp 500+ watts. 

My understanding is if I tie 2 of these together in series (one with a floating ground) I could reach 24v. The amps would be at 45 available, because my assumptions are that current is dictated by the lowest amount of amps put out by either PWS...I was then looking at buck (step up/step down) convert with potentiomitor to dial down the voltage for slower cars when racing with the kids... And dial up when goofing around with some of the Vipers and Wizzards I'd love to get into Tinkering with. The cars would theoretically only draw what they need from the amps at any given time. 

A 15 or 20 amp bus fuse at each of the 4 driver stations for added safety and components protection.

My grey area is the buck converter. By introducing this into the circuit, would this choke the amps available as well? 

Sure I can buy a ready made variable PWS with constant current capability... But where is the fun in that? 

This is all academic at this point, but I am Striving for the most satisfying experience of this hobby.


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## Rich Dumas (Sep 3, 2008)

*R O Car*

Restricted Open cars usually are based on aftermarket chassis like the ones from BSRT, Slottech, Viper Scale Racing and Wizzard. They have very powerful motor and traction magnets and a very low ohm armature. Cars like that can pull 10 amps when they start up. An RO car did a 1.8 second lap on my 50 foot MaxTrax road course.


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## twolff (May 11, 2007)

Patrick32218 said:


> @Rich Dumas
> 
> As always thank you ? for your detailed and succinct response. I am learning a lot from these forums.
> 
> ...


I'd normally tell someone not to mess with server power supplies, but knowing that you have to float the ground on one suggests you know what you are doing. As long as you know how to float the ground and test for same, you should be fine. If you are not sure, don't.

Adding voltage regulation to the circuit won't affect the ability of the supply to deliver current. The regulator will need to be capable of passing enough current to meet the peak demands of the "track". I would fuse the connection between the supply and regulator at just over the current rating of the regulator so it does not get cooked if something goes wrong.

15A fuses at the driver stations seems high to me. I don't remember what I used in mine w/o digging them out of storage and I'm too lazy to look it up myself right now. I know I followed someone else's advice on the fuses I used in the driver stations. My application is only a 4x8 Tomy track with Lifelike being the hottest cars run.

We've really wandered way past the initial topic of this thread eh?

Set power supplies are all pretty much "scrap".


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## Milton Fox Racing (May 27, 2014)

From post 12 on could be another thread topic, but it still seemed to fit under power supply.

Give me an appropriate title for a new thread and I can split this one into two conversations. :cheers2:


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## Rich Dumas (Sep 3, 2008)

If you put two power supplies in series the same current has to go through both of them, so the limit with respect to amps would be the lower rated power supply. A 15 or 20 amp- fuse would give you almost no protection at all. In order to do you any good the fuse must be the weakest link in the chain, which would include the power supply, the wiring, the track rails, the controller and the car. The biggest hazards are a dead short across the track rails, a miss-connected controller or a shorted motor. Some years ago I was racing on a nice custom built HO track that had a 20 amp power supply, but no fuses beyond the one in the power supply itself. Somebody hooked up his controller wrong and the track rails where the car was stopped got hot enough to curl up and melt the track. At another track a short circuit caused the wiring to get so hot that the insulation melted. A few bucks spent on fuse holders and fuses would have avoided a lot of grief.
If you know the ohm value of the car's motor you can calculate the maximum amps that it will draw, the actual draw once the car gets moving will be much lower and you would want to use a fuse or breaker that is somewhere between the stall and running amperage. It is nice to have a power supply with an amp display, that way it is easy to see what the car is using. As a general rule you would want to use a fuse that is four times the lowest value that you would see on the amp display. If you wanted to go by the starting current you would have to know what the ohm value of the car's motor was and that can only be measured across the commutator, measurements taken across the motor leads are not accurate. You would want the fuse to be one third of the starting current value. If a car has a 6 ohm armature and the track is running at 18 volts the starting current will be 3 amps, so a 1 amp fuse for each lane would be appropriate.
There are power supplies with an amp adjustment. Some people think that they can just turn that down, rather than using fuses. If you do that you will have protection, but your cars are not likely to run properly. The reason for that is that the cars do not use a constant amperage, the starting amperage will be about 12 times the minimum running amperage. If you have four regular Tyco 440X-2 cars on the line at the start of a heat when the power comes on the total draw would be 12 amps if you actually had that much power available. It is a good thing that the motors only draw that much current for an instant or everyone would be forced to buy a big power supply. If you turn down the amp control and you have more than one car on the track the chances are that your maximum current draw will be exceeded and that the power supply will drop the output voltage. One during a practice session we found that the cars kept slowing down. If there were just one or two cars running there was not a problem, but with four cars the power supply seemed to be cutting out. When we checked the power supply we found that the amp control had been turned down. For that reason I recommend that you always leave the amp control turned up.


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## Patrick32218 (Nov 14, 2019)

I do apologize for hijacking the thread as it were but given the amount of feed back, I am really glad I asked ?. Suffice it to say, placing the fuse before the converter makes so much more sense as I read the replies. 

For safety sake, it might be prudent to just buy the appropriate power supply with the components built in opposed to reverse engineering server power supplies for this application. If it was just me running on the track, I probably Would peruse this line of curiosity. But with the neighborhood kids and my own periodically racing their cars, the potential risk just outweighs the rewards? 

I truly do appreciate the knowledge everyone has shared though. In the meantime, I will run with the 2 laptop PWS's and see how far I can push those 3 ohm arms , and switch the kiddos out to the 4 Tommy Tri-packs when they want to race the stock stuff.


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## Milton Fox Racing (May 27, 2014)

I didnt (and still dont see it as a hi jack). The thread topic is still about power supplies....

One other thing that can be done is to put a post title in - that is easier to pick up by the search engines, but is not a posting requirement in any way. :cheers2:


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## Rich Dumas (Sep 3, 2008)

I should have posted this link to my article about power supplies sooner: https://drive.google.com/file/d/1r_mey6LXg4kmp6sX4U3lU-fDA72pXhfj/view?usp=sharing


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