# Volts & Amps



## NHawk52 (May 16, 2005)

Forgive me for beating a dead horse here, but after searching the forums and reading all the past posts, I'm still in the dark (no pun intended) about the how and why of electical supplies. I'm aware that most "wall warts" supply 15-24 volts and most afford merely 1/3 amps (and the "ideal" is 5 amps per lane?!?). Being electically-challenged (never took shop in high school) I don't fully understand the purpose and goal of suppling specific numbers of volts and amps to the lane(s). In my initial stages of track configurations I have found the a single "wall wart" for a 2-lane track was insufficient to maintain consistent power throughout the course (numerous dead spots) and each lane's activity affected the other. Having rewired it to allow one pack connection per lane solved both problems. I currently use many chassis models ranging from TJets and TJ500's to SG+ and Lifelikes.

I guess my remaining questions at this point are: What purpose/advantage does more (or less) volts serve? And what purpose/advantage does more amps serve?

Thanks,
NHawk

P.S. No, I can't go out and buy a big commercial power supply for "my son's" (  ) home track. I'm an OLD single dad on a very limited budget.


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## AfxToo (Aug 29, 2003)

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## blackroc (Mar 26, 2005)

Dang AFX... you even made sense to me! Now that's saying something. That really was a big help and explained a lot of things I had observed (such as the startup power demand) that I hadn't really understood the why's of. Thanks.


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## Anti-Cop (Jan 25, 2005)

as usual, something I THOUGHT I knew about... it proves I didn't really. AFX, yer help on these forums and info is always so packed! I appreciate reading posts by you. Always able to learn something!


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## Slott V (Feb 3, 2005)

18 VDC is the standard for commercial HO slot car racing. Amperage is based on your needs. Cars with high downforce magnets require mroe amps to move them. More amps = less motor heat.

In simple terms; Voltage could be considered horse power and amps could be compared to torque. More volts gives you more top speed and more amps gets you "out of the hole" quicker, like at the start of a straight. The advantage of more amps will level off at some point, again depending on your demands.

The early power supplies from Aurora actually made a couple of amps. Newer "wall warts" are cheap transformers. The Tomy unit says 7 VA, or "volt-amps", which is different than true amperage output. Most wall warts are rated with no load, which means you get a lot less than rated when a load is applied. Wall warts will offer pretty good power for stock cars, again depending on layout size. Once you increase downforce and go to a hotter wound motor like a BSRT "spud" wind you will notice a big difference between stock power and a filtered power supply or batteries. More expensive filtered DC power supplies output much "cleaner" power which little slot motors like.

Scott


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## NHawk52 (May 16, 2005)

That's a gives a more progressive understanding (I think  ). Thanks!

So... in it's simplest form, a higher VA supply results in a faster and/or quicker car? And - in an ideal world - a VA power supply that more closely matched the motor-produced voltage of the car would be the most efficient in terms of speed, torque, and heat? Is that the reasoning behind the "5 amps per lane" goals? Realizing that there are innumerable variables involved between brands and types, are there ideal and/or maximum ratings for the various "box stock" cars?

A sideline question: The plug recepticles of the AFX, Tyco, and Lifelike power track appear very similar - are the wall packs interchangeable between track brands?


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## micyou03 (Apr 8, 2003)

What blackroc said.


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## Slott V (Feb 3, 2005)

I think 5 amps per lane is an average obtained over the years by testing the highest performance HO slot cars. There's a lot opinions on that subject. If you had a 5 amp supply on a "home" 4 lane track, that could work fine for your situation if you had slightly modified cars and only a couple of friends racing from time-to-time. If you had monthly club races with lots of guys and lots of modifications, you'd probably want at _least_ a 10 amp supply. Some commercial tracks only run on battery power to maintain consistency between racing events/locations.

You can install any type of power supply to any track by splicing the connectors into the wires. Keep in mind that early TJet cars were only designed to operate within 14-18 volts. Newer Tomy sets come with power supplies up to 22 VDC. If you run numerous wall packs in parallel, make sure they are all the same.


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## ParkRNDL (Mar 20, 2002)

NHawk52 said:


> A sideline question: The plug recepticles of the AFX, Tyco, and Lifelike power track appear very similar - are the wall packs interchangeable between track brands?


 I've switched wallwarts (and controllers) between Tyco and Lifelike. Tycos have a little nub on the plastic on one side that had to be cut off, but it didn't affect their operation at all. I've also modified a couple of Lifelike terminal tracks so that each lane gets its own wallwart.

--rick


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## newbombturk (Dec 2, 2000)

*More Amps, More Power*

The three most basic units in electricity are voltage (V), current 
(I) and resistance (r). Voltage is measured in volts, current is 
measured in amps and resistance is measured in ohms. 
A neat analogy to help understand these terms is a system of 
plumbing pipes. The voltage is equivalent to the water pressure, the 
current is equivalent to the flow rate, and the resistance is like 
the pipe size. 

There is a basic equation in electrical engineering that states how 
the three terms relate. It says that the current is equal to the 
voltage divided by the resistance. 

I = V/r 

Let's see how this relation applies to the plumbing system. Let's 
say you have a tank of pressurized water connected to a hose that 
you are using to water the garden. 

What happens if you increase the pressure in the tank? You probably 
can guess that this makes more water come out of the hose. The same 
is true of an electrical system: Increasing the voltage will make 
more current flow. 

Let's say you increase the diameter of the hose and all of the 
fittings to the tank. You probably guessed that this also makes more 
water come out of the hose. This is like decreasing the resistance 
in an electrical system, which increases the current flow. 

Electrical power is measured in watts. In an electrical system power 
(P) is equal to the voltage multiplied by the current. 


P = VI 
The water analogy still applies. Take a hose and point it at a 
waterwheel like the ones that were used to turn grinding stones in 
watermills. You can increase the power generated by the waterwheel 
in two ways. If you increase the pressure of the water coming out of 
the hose, it hits the waterwheel with a lot more force and the wheel 
turns faster, generating more power. If you increase the flow rate, 
the waterwheel turns faster because of the weight of the extra water 
hitting it. 

In an electrical system, increasing either the current or the 
voltage will result in higher power. Let's say you have a system 
with a 6-volt light bulb hooked up to a 6-volt battery. The power 
output of the light bulb is 100 watts. Using the equation above, we 
can calculate how much current in amps would be required to get 100 
watts out of this 6-volt bulb. 

You know that P = 100 W, and V = 6 V. So you can rearrange the 
equation to solve for I and substitute in the numbers. 


I = P/V = 100 W / 6 V = 16.66 amps 
What would happen if you use a 12-volt battery and a 12-volt light 
bulb to get 100 watts of power? 


100 W / 12 V = 8.33 amps 
So this system produces the same power, but with half the current. 
There is an advantage that comes from using less current to make the 
same amount of power. The resistance in electrical wires consumes 
power, and the power consumed increases as the current going through 
the wires increases. You can see how this happens by doing a little 
rearranging of the two equations. What you need is an equation for 
power in terms of resistance and current. Let's rearrange the first 
equation: 


I = V / R can be restated as V = I R 
Now you can substitute the equation for V into the other equation: 


P = V I substituting for V we get P = IR I, or P = I2R 
What this equation tells you is that the power consumed by the wires 
increases if the resistance of the wires increases (for instance, if 
the wires get smaller or are made of a less conductive material). 
But it increases dramatically if the current going through the wires 
increases. So using a higher voltage to reduce the current can make 
electrical systems more efficient. The efficiency of electric motors 
also improves at higher voltages but only t a certain degree. 


volts x amps = watts 

amps = electrical "leakage", such as in the conversion of the 
electrical energy to heat energy or kinetic energy. 


Power Wire Specifications 
Cable Size 
American Wire Gauge Current Capacity 
Amperage (amps) 
1/0 350 
2 225 
4 150 
8 100 
10 60 
12 40 
14 25 
Accidentally speaking....
Remember: It's the Volts that "jolt" you. 
It's the Amps " kill 'n cook" you.





I have been around slot cars since 1966/67. I now subscribe to the "More Amps is better ! " school based on my experience. I currntly have a fully filtered high amp supply. 30 amps does it for me on a 4 lane track. 


Rocky


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## Manning (Mar 2, 2004)

NHawk52, the dead spots are bad connections between track sections. A power supply won't fix that. Track needs to be taken apart at the dead spot and the connections tweaked. Split the track at the terminal track (behind the car), and drive around until the car stops. Fix the last joint. Keep going until the car will go all the way around....... Hope that made sense. 

If you are happy with the single transformer per lane, great (what I run). You may want to consider putting a jumper in the track about halfway around from the terminal track. Keeps the voltage up. Copper wire is MUCH less resistive than the steel rails and all the joints in the track. Put either the terminal track or the jumper about halfway down the longest straight, and the other about halfway around.....

Like everybody has said.....amps=acceleration (to a point, motor will only require so much), voltage=speed.


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## AfxToo (Aug 29, 2003)

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## Captain Fred (Feb 19, 2000)

Great thread! This ought to be on a sticky.

Thanks guys!


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## scratch (May 16, 2005)

Interesting . . .
- - - -
"Like everybody has said.....amps=acceleration (to a point, motor will only require so much), voltage=speed."

"I've often heard the plumbing analogy and it holds water (ha ha) for purely resistive circuits (which actually don't really exist in the physical world). The only reason I bring this up is because electric motors are electromechanical and electromagnetic devices. The plumbing analogy falls short once the motor starts spinning. I can't think of the plumbing equivalent to 
ounter EMF, the voltage that the spinning motor produces because the armature windings pass through a magnetic field. The counter EMF opposes the voltage from the power supply. Once the motor is spinning the effect of the counter EMF is the predominant factor that governs motor current. 

As far as "voltage being horsepower" and "amps being torque" ... that's not entirely a good analogy either. Horsepower is, by definition, power. I only bring this up because if you live outside of North America and the UK motors of all sorts (electric, gas, etc.) are rated in SI power units, that is in watts or more commonly, kilowatts (kW). Not a big deal as far as slots are concerned."
- - - - -

Water analogy only works in the "resistive" world as intimated in another post ... once motor turns, things change. Once a DC motor begins to "turn," stuff becomes quite dynamic even for the lowly DC motor, and all is not linear.

For example, in the good old days I ran a two-battery car set up. Which gave me unlimited amps and 26.4 volts of pure DC. Best set up I ever had. I now have TrakMates that put out 10 amps and some 30 volts each. I run 1/32 cars on a Carrera four lane and have two TrakMates, so each lane gets "uninterrupted" power, so to speak. There is a very slight change when one car powers up from a stop and the other is running. Again, goes to resistance. Goes to amps drawn. Goes to circuitry not being 100% split. Goes to manufacturing economies.

As for the DC battery setup ... motors also ran much cooler, no chance of AC leaking through.

As one poster intimated, a motor will only use "up to" amps it can. Whereas you can "over cook it" with too many volts. That's where the water wheel analogy falls short. Since a DC motor may have ... as in my battery case huge amount of amps to suck from. But will only use what it can "draw," not what is available. I'm not going to get in to all the formulas, others have done a good job of that. 

Draw & Push
DC motor "draws" amps ... volts on the other hand are "pushed" through the motor. That's the big difference ... "draw/amps" and "push/volts" and what I felt needed saying ... thus this little missive. Hope helps others understand the why DC motors in their cars run the way they do. DC motor will only use so many amps, but will use as many volts as you supply it up to a certain point . . . 

That's why substituting volts for amps won't cut it other. 12 volts at 6 amps, ain't the same as 24 volts at 3 amps, DC motors are NOT light bulbs. Doing so could ruin your day when you "fry" your little wonder. "Well, let's see how about 72 volts at 1 amp?" Briefly perhaps ... but not for long.

Now, having said the above. Yes, I do run my 12-volt motors well beyond that. Seems to a point, the little wonders will accept more volts than say what they are "wired" for. That said, I run a home track, in which the applied voltage is not constant, max used only in spurts, max voltage is "maxed" briefly coming out of say, a corner, stuff like that. 

Probably would be a bad idea if one had 50-foot straights and ran the little motors at such voltage limits over many laps. Also, when buds are over, or I'm over at their place, we run races measured in minutes, not hours. So our motors are really not stressed that much. I must submit, that I continue being amazed at how much abuse slot based DC motors will absorb, before finally giving in.

Light bulbs are resistive, DC motors dynamically make use of amps and volts over their working range, and the relationship between this use is very dynamic. Its the dynamics over the applied working range of our little motors that mucks up the light bulb and water wheel analogies. 

One poster mentioned EMF, yet another dynamic that light bulbs and water wheels don't supply. Everyone knows light bulbs don't produce voltage, motors do, EMF. Obviously water wheels don't. For example, our little DC motors will produce power, if power is supplied externally. Before present day alternators in cars. Vintage cars made use of generators, a DC motor used in reverse so-to-speak, supplying power as turned by the car's engine. For this missive won't get into PM versus WM and the like. As DC motors increase in size, economies, weight, and so forth dictate going from magnets to windings. But thought the car generator concept might help a little.

I'm trying to stay away from formulas and theory. Trying to stay with application.

A car battery with 500 amps potential and 13.2 volts is perfectly safe for most slot DC motors we use ... even though amps are huge. As said above, I used two car batteries for 26.4 volts. With obvious quick fuse or circuit breaker used. I used a telephone company spring loaded wire fuse, mechanical to be sure, but always worked and I could "see" the thing. 

DC motors [PMDC] that we use are not overly efficient, create heat, have lots of resistance, and so forth. I've never worried about, nor figured "loss" to drive wheels and track, but it must be rather large. Fortunately, our cars HO, 1/32, whatever are so over powered -- "loss" is not an issue.

On my TrakMate I always run it at max amps, and say 27 volts. I don't care if I'm running an RTR or an amp sucking Parma 16D. If the little motors begin to heat up a bit, I dial down the volts, not the amps. Again its the voltage "push" not the amps "drawn" that causes problems, notwithstanding stalls, shorts, and other obvious occurrences. Another problem is cheap transformers leak AC like mad. DC motors don't respond well to 60-cycle AC.

In other forums I sometimes see a post from a guy who is really ticked about his AC to DC trans ... and makes sure the whole world knows it. Expense in transformers is in the manufacturing to produce amps, not volts. One reason most wallwarts produce such puny supply of amps. 

I hope this helps a little, I deliberately stayed away from formulas, since the dynamics of formulas when figuring "push" [volts] and "draw" [amps] would really muddy things up.


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## AfxToo (Aug 29, 2003)

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## roadrner (Jul 21, 1999)

Damn, I so confused! DOH. 

Thanks for the electricity 101 class. :thumbsup: rr


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## TK Solver (Mar 18, 2004)

Yep... I'd like to see all the muddy math too. Seems like there would be some differential equations involved. If I had the math, I could whip up a model in TK and serve it over web for all of us to explore. Hey AfxToo, I sent you a PM along those lines. I'd love to add a little Slot Car Math section to the TK Solver section of our web site to make things a little less stuffy.


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## NHawk52 (May 16, 2005)

Sure liking all this detailed info!! And I guess this old horse ain't dead yet - I'm getting a much clearer veiw of the topic and much more info than I found elsewhere. Thanks a great deal to all !!

NHawk


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## Autotech (Dec 13, 2004)

*Regulated Power Supplies*

As an automotive instructor and driveability tech what I have seen electrically is availible circuit power is related to voltage regulation and stall amperage. Automotive examples are helpful in understanding how these "loads" react. Not discounting EMF in the amps needed part of the running equation my question always will be on a regulated power supply what is regulated volts or amps? Other than a Lambda type supply which is both, if you exceed system rating current limiting could either be obtained by lowering
the system voltage (or washing it out) or by adding additional resistance into
the circuit to maintain voltage. On a 10 amp power supply at 18 volts 4 cars at 6 ohms each at the moment of startup will draw 12 amps 18/6=3 3x4=12
3 ohm modified motors should draw 24 amps at initial stall amperage startup.
RO becomes even more of a problem as motors can be 2 ohms or less. 18/2=9amps 9x2cars=18 amps. While I will conceed that is startup only anyone who has raced RO has experienced how a fast car will go "soft" when other cars are put on the track. That experience comes from the multiple parallel circuits of the cars being run at the same time. Normally the math would be resistance would be divided by the number of circuits ie. 4 6 ohm motors would be 6/4=1.5 ohms which would give us 18/1.5=12 amps. With that said the real readings are always a little less than the hypathetical.
Also the formula for unequal resistors show that the resistance will always be less than the divisors portion hence the lower ohm motor will "rob" from the higher ohm motor as electricity will always take the easiest path to ground.
The higher ohm motor will suffer if the amperage is limited to less than a level that will satisfy all the motors on the track. Granted the motors are not running at capacity in most cases, Rocky you're the exception even so think of RO with 4 cars on a 10 amp supply at 1/4 amperage draw @ 2 ohms is still an amperage draw of 9 amps if no one keys their throttle. What you can see is one off can result in one or two more cars offing due to surges in power on tracks. This is why we use batteries or our Lambda duel amperage/voltage regulated 36 volt 34.5 amp power supply. Dave


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## AfxToo (Aug 29, 2003)

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## TK Solver (Mar 18, 2004)

I really enjoyed this thread so I couldn't just let it stay dormant for another month... I've got two Tomy transformers plugged into one surge protector and two more plugged into another. The surge protectors are plugged into two different outlets across the room from each other but they're both on the same circuit. My track is a four laner with about 72 feet per lane now. There is a bit of a drag at first when four cars start on the track at the same time and if a car goes off the driver in the next lane on that track gets a noticeable surge. It's hard to believe that a standard household circuit with two surge protectors can't absorb the effects of a deslotted car but it's true. Running the four Tomy transformers one to a lane helps but it doesn't completely wipe out the problem. Of course, I've also got a PC and monitor on the circuit and I'm sure the 8 can lights in the ceiling draw some current as well. I'm thinking the problem is with available current, not voltage. It's not as bad as when my shaver bogs down as my wife fires up the blow dryer but it's noticeable. What if I ran a direct line from my main to assure that I'm getting clean A/C to my surge protectors? Each of those can support 15 amps of current.


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## AfxToo (Aug 29, 2003)

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## TK Solver (Mar 18, 2004)

Yes. One Tomy pack per lane.

I'll probably get a TrakMate supply for $110 plus shipping. I assume I just splice it into some Tomy track connectors.


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## AfxToo (Aug 29, 2003)

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## TK Solver (Mar 18, 2004)

No, the lanes are not isolated so the power is being shared. That suggests that only the paired lanes will be significantly affected by surges. Isolating the lane seems like it would help with surges but would also reduce the distribution of power around the track. I've got 82 to 83 track pieces along the path so I know I'm losing some power through all those connections. I've been assuming that spacing the terminal tracks distributes power around the track more evenly. Thank you for the links and all your help, AFXToo.


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## AfxToo (Aug 29, 2003)

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## TK Solver (Mar 18, 2004)

That's exactly the setup I've been running. I've got driver stations positioned at the four corners of the layout with a terminal track connected to a power pack and one controller at each. It's just like the diagram on Gregory Braun's site. I've been assuming that the two terminals on the same track share in powering that track even though Greg's site states that each lane will be powered independently. I also know that if I try holding two Parma Econo's (with metal triggers) on the same side of the table, I get a tingle when I pull one of the triggers.

I'm also using a couple of extra terminal tracks (one on each track) as straights but they're not connected to any controllers or power packs, except via the rails of course. As long as they're orientated the same as the rest of the terminal tracks I didn't see any harm in that.


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## Slott V (Feb 3, 2005)

Without reading all of the comments in this thread in depth-

Your wall outlets in your house have nothing to do with power surges in your slot cars. You could run a dedicated circuit just for track power but I've never heard of that. Unless you need dedicated 220 at a specific outlet, there's no need for a special outlet and breaker. If your wife's hair dryer dims your lights that much I'd take a look at your home wiring regardless of your slot car problems! :drunk: 

If you are using stock power/controller hook up sections, did you remove the cover underneath the track section and disconnect the common ground from one of the lanes that both lanes share? Just plugging in one controller and wall wart at each power connection won't isolate your lane power. That trickle effect you are feeling is caused by the common ground.

Next, you should run at least 2 wall warts in parallel per lane, isolated. Especially if you run any magnet cars. You should also have power taps every 10 feet or so with plastic sectional track.

If you're serious about your slot racing, dump the controller hook up sections and wire the track correctly yourself with better wiring, lane stations and filtered power supply.


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## Slott V (Feb 3, 2005)

If you want a simple fix to your situation;

- break loose the common ground strip under each of the 4 track power connector sections so that only one lane will get power from that section.

- Get rid of the extra, empty power connection sections.

- Run some wire from your power connection half way around the track to a track connection. In your situation you could get away with 22 ga phone wire. You should be able to pinch this GA wire between the track rail connections. Make sure the wire doesn't stick up above the track surface.

- Now try running some cars. You should feel a huge difference.

- Next will be purchasing a terminal block so that you can run multiple power taps branching out every 10 feet or so.

This is a simple solution in the interim until you can wire your track more efficiently.

-Scott


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## TK Solver (Mar 18, 2004)

I'll try disconnecting the common grounds and see how that works. I have 8 wall warts available so I could try splitting each lane into 36 foot sections to see if that makes much of a difference in power. The cars go too fast for most drivers as it is, so power isn't a problem. And as long as the power is the same for all four lanes, I don't see an issue there. It's the surge during a deslot on a paired lane that's motivating me to look into this more. It sounds like isolating each lane will take care of that. Thanks for the help.


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## Slott V (Feb 3, 2005)

TK-
The surge from stock tracks is one of the most common problems discussed among home racers. One power pack per lane is the budget cure, but those common ground strips must be altered if you use the factory power connection. Most are spot welded to the rail, so you'll need to pry carefully or cut the strip with side cutters.

Losing power across a large sectional circuit is probably the next common issue. Short of soldering all the rails together, power taps are the solution, along with inspection of all your connections. This is even common with model railroads. Here's a tip- tape a controller wide open. Now take a car and push it along the rails with the back wheels elevated. As you go across connections you will hear the pitch of the motor drop when you encounter a bad connection. In some places the car may quit altogether. BING! Time to tweak that connection. Onto the next one...  

If you do run multiple power packs, make sure you wire them in parallel, or positive to positive and negative to negative. That will keep the voltage the same, yet boost amps a bit.


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## TK Solver (Mar 18, 2004)

I currently have two power packs on each same track, without isolating lanes, with one controller at each terminal. If I add a third power pack to each track, roughly cutting the track into three sections, but don't isolate power to the lanes, would there be any advantage? Any harm? I would make sure that the direction of the power was the same on the three connectors.


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## AfxToo (Aug 29, 2003)

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## TK Solver (Mar 18, 2004)

I experimented with adding a third power pack and terminal to each track (with no controller connected there) and it seemed to have no effect at all when running a single car. I wasn't able to test two cars so I'm not sure about that. (I really could use having a clone around sometimes.) I was also curious to see if the 3rd power pack on its own would power a car even if the controllers were attached at different terminal tracks, so I unplugged the other two. It does not. The third pack apparently doesn't interact with a controller elsewhere on the track. Still not sure how it interacts with other packs though. It would be nice if adding the third pack acted like a power tap AND dampened the surge effect when one car deslots.


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## ParkRNDL (Mar 20, 2002)

I think isolating the lanes will make the difference. I have 2 old Aurora 20v packs on a 2-lane layout using Atlas track with the old screw terminals, so it's easy to isolate the lanes. Both packs are plugged into the same power strip. I never felt any surge between lanes running anything from stock Tjets to stock 440x2s. I also isolated the lanes as an experiment on some old Lifelike track that I had around, and it worked fine. Scott was right, it takes a little cutting of the metal conductors, but I was even able to do it without soldering by using female spade connectors. it looked like this, and Tyco will look exactly the same underneath, but i never looked at the bottom of Tomy track... is it similar?










hey, this got me thinking of another goofy question i have about something that happens between lanes on my layout, so I'm gonna start a new thread...

--rick


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