Modern AFX and Tyco slot car motors require a power supply producing 18 to 20 volts of direct current (VDC), while older Model Motoring cars require 20 to 24 VDC. The wall-outlet power pack supplied with most boxed racing sets is not sufficient for use on large table-mounted racing layouts.
DC power supplies normally have two specifications, the output voltage and the output current. Modern HO slot car motors require at least 18 VDC, and 1 ampere or more of current for proper operation. Most of the DC power supplies currently being manufactured provide only 12 to 13.8 VDC. These WILL NOT work for HO slot car tracks. They will however work properly for larger 1:32 and 1:24 scale slot car tracks.
A good quality DC power supply is essential to safe, trouble-free racing and prolonged motor life. Investing in a good power supply will quickly pay for itself in motor savings alone.
A good rule of thumb to use when determining the size of the power supply required is to multiply the number of lanes by 1 ampere or more. Especially long layouts or very hot motor armatures may require more power, but 1-2 amperes per lane should be sufficient for all but the most demanding racing situations.
A 5-10 ampere DC power supply would be a good choice for a long 4-lane racing layout. This should provide sufficient power with an adequate reserve.
Power needs to be applied evenly around the entire race track. Slot car tracks with lane lengths greater than about 20-25 feet will need to have power applied at several locations. The rail connections at the joints in plastic sectional track are the single largest factor contributing to voltage drops as the cars move farther and farther away from the power terminal track.
It is often said that power should be applied every 15 or 20 feet for an even power distribution. This is true, but an even better way of determining power terminal track spacing is to count track joints. It is the joints that rob your track of power not just the length. Applying power every 12 to 15 track joints will assure that your track is properly powered.
It is important to determine where power will be applied before you build your track and mount it permanently to a table. Racers who skimp on adequate track power distribution will be disappointed when they have completed their track and find that cars slow dramatically on those sections of the race track farthest from the power taps.
Replacing the power supply with a unit producing higher amperage has very little effect on power distribution. Inadequate power distribution produces voltage drops around the circuit. All of the amps in the world can't overcome this drop in voltage though.
Powering each lane with 1 or 2 amperes is sufficient if power is distributed evenly. It's far more important to apply track power evenly around the racing circuit than it is to have a high-output power supply feeding a single set of power terminal tracks. Regardless of the power supply output, cars will slow down dramatically as they travel farther away from the power source.
Generally speaking, a 4-lane race track mounted on a 4x8 foot table would require 2 or 3 power taps, while a 4x12 foot table would probably require at least 4 or 5 taps. Even larger and longer race tracks may need as many as 10 power taps. Count the joints for a single lane and then divide by 12 or 15 to get a better idea as to how many power taps your particular track design requires.
Commercial HO Power Supplies
Astron is a good source of high quality DC power supplies for HO slot car racing layouts. Astron offers several nice 0-30 Volt Variable DC Power Supply models producing 10 amperes of power or more. Astron power supplies are fully regulated. A regulated power supply eliminates power surges associated with other multi-lane power supplies.
A large voltmeter and ammeter on the front panel show the current output power status. Output voltage is adjustable from 0-30 VDC. Modern HO slot car motors run at 18 VDC, but with an adjustable power supply you can also reduce the voltage when young racers or novices are running.
Older Aurora T-Jets like slightly higher voltages around 20-22 VDC, so an adjustable power supply is ideal here too. Higher voltages equate to faster speeds, but also hotter motors, so it's always a good idea to stay within the recommended voltage range for the type of slot cars being raced.
I've sold other less capable power supplies over the years, but now I stock only the best. A good power supply is a big investment. Don't waste your time and money on lower-priced units that burn up and can't be easily repaired. Some of the junk sold on eBay is just that junk.
Three different HO Power Supply Models are available: