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The electronics in a standard slot car set are fairly basic in their most simple state; one rail goes to the negative side of of a DC power supply, the other rail goes to the positive, but has a controller (variable resister) between the power and the car. The resistor, in a fully "off" state provides no power to the car, and as the controller is pulled back to fully "on", it provides no resistance and the power supply is, in essence, fully provided to the car. Although this is an effective set up (and employed by probably millions of standard slot car sets) there are flaws to this.
Consider, for example, when two cars are on the track. Voltage is applied to the track, and the cars draw as much current as they need to turn their motors (both of these values are dictated by the power supply). Driver one spectacularly crashes his car, and in that instance, suddenly the complete power is available to car two. With the increase and the human reaction time, driver two suddenly crashes his car - although this example isn't 100% correct, it gives you a non-technical overview of the problem. When you're a couple of kids racing for fun, the problem isn't severe, but some slot racers get very touchy if anything interrupts a race.
Tim McDonough wrote: If you see a power surge in one lane when a car deslots then either the power supply does not have sufficient amperage to supply the total load or the wire guage for the track is too small - thus will not let the full amount of current required by the cars be delivered to the track.
This page is here to discuss some of the issues and work arounds for getting the set running correctly.
The power supply is probably the single most expensive component to a slot car track; some slot racers like to discuss this to a finite level, as you will see on many boards across the globe. I was fortunate enough to pick up one second hand from another Perth racer (Karl), who bought two cheaply from eBay. This power supply can provide up to 20 Volts (incremental in 0.1v steps) with a current draw of 3 amps, it is also a regulated power supply, which means the above scenario (car coming off track, 2nd car gets extra power) is not a problem. I also know as a similar supply is being run on another track in Perth, that it will adequately supply voltage for 4 stock Tomy Super G+ in a race. I'm a bit unclear at this point whether it will also supply enough current for the modified cars we'll be running soon, as they tend to draw more current from the supply which can cause the supply to shut down due to (what it considers) an overload. With my electronics I'm intending to wire the circuit as two seperate tracks of 2, then join at the last possible point. The idea behind this is that if the track ever needs to get upgraded with a secondary power supply, it should be easy to impliment.
Tim McDonough wrote: 3 amps is probably good for a couple of lanes of T-Jets or stock Tyco, LifeLike, SG+, etc. It could be troublesome for any hotter cars or four lanes of any type.
AC or Battery
One interesting topic that was bought up on the was the possibility of using a DC battery, rather than an AC power supply. I've heard of people in the US using car batteries as power for their track, often having a 12V and 6V in series to give 18 volts of power, with a fairly high current draw. It may be something you wish to consider when setting up your track, however from reports I have read across the net, you need to recharge fairly regularly and the usable time for a battery is around 30 to 45 minutes. On the plus side when the power goes out, you can still race (albeit in the dark!).
Breaker or Fuse?
Another point bought up on the was whether to fuse the controllers to stop a short circuit, or whether to go the extra distance and use a resetable circuit breaker. Although a fuse is fairly cheap these days, a circuit breaker means that there would be no replacing of a fuse; fix the short circuit (which is likely to be a car across the track, or possibly a controller not fully plugged in), reset the circuit breaker, and off you go. Although I've initially bought some cheap fuse holders and fuses, I'm reconsidering this and swinging towards circuit breakers.
Americans seem to like the idea of having three screw posts with their controllers having three alligator clips on the end; whilst I see the value of this basic system as a cross-racetrack compatible system, I much prefer having something to plug in. I must also admit that the local Perth people use ¼" sockets and plugs, which has spoilt me from the start. (Update: One of the members of the HobbyTalk Forums informed me the alligator clips stopped substantial damage to the control if someone trips over it)
One of the members of the has suggested that XLR connectors may be the way to go. An advantage (or disadvantage) of this system is that the cable is securely connected from the controller to the table.
The advantages would be:
But the disadvantages:
In further discussions on this point, one of the professional raceways in Perth has been cited as saying that the Electric Plug type socket controllers works best for him. Although I don't personally agree with this (due to the possibility of electricution), he said that these offer him the most flexability in terms of getting a plug in and out of the socket without damaging either, and for cost. He said that he had tried placing one inside a 240V AC outlet, and it blew the resistor and did nothing more.
The standard Tomy controllers are small. In the hand of a child they may be adequate, but even from my youth I remember comparing the AFX controller to the far bigger and bulkier Scalectrix controller, with the later being much easier to hold and control.
We have also "standardized" our controller connections a bit differently to everyone else. This was done accidentally, but now we are all using the following diagram for connecting controllers to the track.
The rails are where the cars draw their power from, in their most simple form, they are merely a continuous circuit of ground and a positive (DC) voltage, as shown in the diagram below.
They are the most critical part of the track, and possibly one of the most debated parts of building a HO track. Whereas the builders that are in larger scales have two generic options (either braid for magnetic or copper tape for non-magnetic) the options in HO seem to be less rigid and more builder influenced. The problem for a HO builder is that the rail, as well as supplying power, also provides a place for the magnets to provide downforce towards the track. If there is too much magnetic pull, the cars won't come off the track which removes the competitive part of racing, and will also provide a great deal more downforce on the car, which can eventually burn the motor out. With too little magnetic pull, cars will not use their downforce, and faster cars will fly off and cannot be used to their full potential.
One builder who sent me a comment on the site (Craig Jones from Vortex Raceways in Sydney) has gone to the trouble of ordering 0.4mm sheet steel and cutting it into 2.8mm strips, thus giving a rectangular rail which could be mounted with a small piece of plastic on the inside. This technique is used by (most notably) Brad Bowman in the USA and emulates how the Tomy track works. (Tomy track uses 0.4mm x 2.7mm size rail) One point to note here is, when routing a track, it is hard to get a bit which will match the small width specifications (0.4mm) of the original track, and far easier to create a piece of plastic with these dimensions.
Below is an example from the Vortex site which shows a test piece of track with a car sat on, from what I have read, two pieces of plastic are inserted into the rail groove after the rail has been placed in. I'm guessing that some type of glue holds it all in place, and am keen to see how this track turns out.
Another builder in Germany, Christoph Mueller, has used non-magnetic rails in the form of Aluminium and Brass - in a couple of emails we exchanged, he stated that his passion was for the non-magnetic cars and thus the power was more important than the down force. His first design was using copper tape back in July 2004; then using copper solder braid. Neither of these solutions gave him the experience he was looking for - my understanding is that the tape will only work with modified HO cars (using a "Slide Guide", as outlined on W.M. Brant's website - please see the links section).
He went on to say he then tried Aluminium, but cars would not run without wrapping the pickups with Aluminium Foil, but had great conductivity for the power to the cars in this state. One downfall was the oxidization of the rails, stating that after a few hours it noticably slowed the cars down. He has since rebuilt his track using brass for the rails and found this is a more reliable solution. After non use for several weeks he can give it a quick dust over and the track is good to run.
Another area where rails are critical is their depth in relation to the surface of the track; and the faster the car, the more critical this becomes. The smallest of kinks in the rail in a horizontal plane will cause the modified cars to launch at incredible speeds into the air, potentially causing damage to either the track or the car, or any surrounding material. The rail should be exposed a mere 0.3mm from the surface, with a +/-0.08mm allowance. It should be noted, however that the major manufacturers have a +/-0.15mm tolerance for production track.
The timing set up is relatively easy and inexpensive these days; with cheap (older) computers readily available and able to do the job, plus some free software located on the web. Two packages we use in Perth are Lap Timer 2000 and Ultimate Racer (please see the links page). Both of these use a very similar interface that connect to the printer port on the PC and use a mechanism to "trigger" when a car goes past, having an accuracy of around 1/1000th of a second.
The methods for triggering are varied, so far in my research I have found that there are a few methods used:
Whilst there is much debate as to what provides better functionality, my personal feelings towards these methods are that the reed switches provide an accurate and more aesteticly pleasing look for the track. Of course, the best solution is always what works for you, and this option may change in the future.
Items that don't fit into the above categories or transcend two areas.
Relays
It is possible to add relays to the track power and timing set up. This can provide (depending on wiring) two things; firstly the track power can be OFF until the race starts, and secondly the track power can remain ON until the race ends.