10 replies to this topic

[ovalracer63]

I have a question for you electronic wizards out there, since I am not one. Let me explain, first I have a small 1 lane rally track that is on a 3 x 6 ft. platform, my question is can I or is it possible to take a pc power supply and use that to run the track? I won't be running anything but one car at a time and there will be no lights or any other type electrical connections to the track. Any help would be greatly appreciated. thanks

Tom

[triggy]

Yes, that's exactly how we are powering our new rally track, Limestone Pass. We connected it up last Sunday and all went well. We are also using the same PC power supply to power our timing box also.

[Johnnyfly41]

Sure you can.

a regulated DC supply is what you want, you would like constant voltage output regardless of current draw. Most walwarts it has been my experience are very poorly regulated. My carerra supply floated up to 18 volts at no load, loaded down to 11 or under with a RTR car driving on the track. not good in my opinion.

On a small track like that, a single power tap is fine. To keep power even, connect to one of the track rails at once side of the track, then the other power rail at a point about halfway around your track. By doing so, the power drop is uniform, no matter where the car is at on the track.

Since you are trying to save money, you probably are not going to put in a variable voltage supply. To be able to vary the voltage, you can use a array of diodes in series. Silicon rectifier diodes capable of a few amps. You can then reduce the voltage by about .7 volts for every diode you are passing current through. that is, if you want any ability to tune the voltage to your preference.

I have huge super well regulated DC supplies on my track, supplies that cost probably 1500 new. I bought them on ebay for between 60 and 80 dollars. I would think you would want a supply capable of a couple of amps, just to have some safety margin.

good luck,

John

[gzminiz]

As I have PC Power supplies laying around I reckon this is what I will be doing. Would a PC power supply handle a 3 laner? I don't need variable as I plan on setting up the drivers stations to be able to select their own voltage (so I can drop it from my son but keep my lane up and race at the same time).

[rick1776]

Read the nameplate on the power supply. It should tell you the current or VA that the unit can supply. 2A per lane would be more than enough for scaly type cars. If you have a bunch laying around just run one per lane. Or parallel three up. Join all the + terminals up and all the - terminals. Oh make sure they are all nominally 12V.

[Johnnyfly41]

I am sorry, I misread your post when I replied, I read "DC power supply" not PC, assuming you were talking about constructing your own.

Word of warning on the PC supplies.

find out the real current capability of the 12 volt output. The total wattage is irrelevant, as that is the sum of all the various output channels the supply has. Another thing, usually their ratings are highly optimistic on those buggers too.

Also, if the power supplies are switch mode regulators and if the 12 Volt output is a secondary voltage as in a fly back type of design, the 12 volt output may not be present or reliable if the primary voltage probably the 5 volt output is not being used.

There are plenty of bit heads on here who know better than I about those issues. Many folks are using PC supplies succesfully, not all are created equal.

Best of luck, sorry for the confusion.

John

[gzminiz]

Johnnyfly41, on Mar 3 2009, 10:51 AM, said:

I am sorry, I misread your post when I replied, I read "DC power supply" not PC, assuming you were talking about constructing your own.

Word of warning on the PC supplies.

find out the real current capability of the 12 volt output. The total wattage is irrelevant, as that is the sum of all the various output channels the supply has. Another thing, usually their ratings are highly optimistic on those buggers too.

Also, if the power supplies are switch mode regulators and if the 12 Volt output is a secondary voltage as in a fly back type of design, the 12 volt output may not be present or reliable if the primary voltage probably the 5 volt output is not being used.

There are plenty of bit heads on here who know better than I about those issues. Many folks are using PC supplies succesfully, not all are created equal.

Best of luck, sorry for the confusion.

John

Is 12v enough? i found a ps that is 12v 18a max and 5v 30a max. If run the neg 5 to neg and 12 to pos, i would get 17 amp ~11-12amp giving me ~4 amp per lane. I can step the 17v down to whatever I want (figured I would use a dial to pop in different resistences to give me 5,7,9,12,15 or whatever) on a per lane bases.

I would rather get a lab setup that is ~15v and 12a and use it in the same fashion. But all I can find is 13.8 (is that close enough?) 0-12 amp for about $70. Rather go with that if 13.8 would be enough.

[rick1776]

gzminiz, on Mar 3 2009, 10:10 AM, said:

Johnnyfly41, on Mar 3 2009, 10:51 AM, said:

I am sorry, I misread your post when I replied, I read "DC power supply" not PC, assuming you were talking about constructing your own.

Word of warning on the PC supplies.

find out the real current capability of the 12 volt output. The total wattage is irrelevant, as that is the sum of all the various output channels the supply has. Another thing, usually their ratings are highly optimistic on those buggers too.

Also, if the power supplies are switch mode regulators and if the 12 Volt output is a secondary voltage as in a fly back type of design, the 12 volt output may not be present or reliable if the primary voltage probably the 5 volt output is not being used.

There are plenty of bit heads on here who know better than I about those issues. Many folks are using PC supplies succesfully, not all are created equal.

Best of luck, sorry for the confusion.

John

Is 12v enough? i found a ps that is 12v 18a max and 5v 30a max. If run the neg 5 to neg and 12 to pos, i would get 17 amp ~11-12amp giving me ~4 amp per lane. I can step the 17v down to whatever I want (figured I would use a dial to pop in different resistences to give me 5,7,9,12,15 or whatever) on a per lane bases.

I would rather get a lab setup that is ~15v and 12a and use it in the same fashion. But all I can find is 13.8 (is that close enough?) 0-12 amp for about $70. Rather go with that if 13.8 would be enough.

The simple answer is no, you cant do what you want, it doesnt work like that. Also putting resistors in series will not give you what you want. To prove the point place a car on the track and press your controller trigger slightly (which is essentially what you want to do with the resistors), no place another car on the same track. Did the speed the car was travelling change? The answer is yes. So placing resistors in series to reduce 17V down to soemthing else will not work.

13.8V is more than enough as is 12A.

[ovalracer63]

Well after posting on numerious forums I got ALOT of info and I want to thank everyone for their input and advice. When I was in the attic looking for a spare PC power supply I happened upon a wall wart from my previous layout which was carrera so I brought it down and hooked it up and it worked great. Again I want to thank everyone.



Tom

[kalbfellp]

The wall wort will not be regulated so voltage will vary depending on the current draw,the PC supply will be regulated.

[Johnnyfly41]

Dont give up on finding a well regulated lab type supply on the cheap.

My supplies are HP 6286A supplies, I dont remember, 0-20 volts or 0-30 volts, doesnt matter, adjustable voltage with fine adjust, 10 amps capability and a adjustable current limit for safety sake. I still fused them. These supplies weigh almost as much as a small battery. In well built supplies, you can tell a lot about a supply by the weight.

On my routed track, we pretty much run 12 volts only.

I have on average about 65 dollars in each of these magnificent supplies. ebay

A well regulated supply is a great thing. The ability to vary the voltage with a knob, and a panel meter readout is a great thing too.

I use one perlane, as much for allowing independent voltage control as anything. this ten amp supply would be plenty or a multi lane track.

A nice companion to a great power supply is a adjustable controller, I am using the Professor Motor with adjustable sensitivity and braking. I find the adjustable sensitivity to be very useful when running a variety of cars. My other controllers are PM diode based, they are great too, till you have the adjustable ones.

It all happens in time,

enjoy,
John