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Can you have too much power?
You cannot have too much power or current. The reason is that your train will only use as much power as it requires. If you were using a 15 Amp controller capable of supplying 24 volts at full current, your layout would use what it needs up to that power level. For example, the average house current is 300 or more Amps at 115 Volts. If you turn on one light bulb which draws 75 Watts, you are only using the amount of power the bulb requires. Voltage can be too high for some controllers, causing too much power to be dissipated in the power transistors. Bridgewerks units do not have this problem; with Bridgewerks controllers, you can run the newer engines that may require more voltage than some of the earlier engines without fear of damage.
Can you have too little power?
Of course. The results will be any or all of the following: Fuse blowing; slow engines; poor sound; not enough power to run area lighting; over-heating of power controller, damaging output transistors, etc.
Is pure D.C. important?
Absolutely! Most engine manufacturers will not guarantee an engine that has been damaged by high ripple current, found in most power controllers. Also, sound systems tend to work much better when used with pure D.C. The ripple current (or distortion) increases dramatically with high current. A controller that has low ripple at 1 Amp may have very high ripple at 10 Amps.
What is the measure of power?
“Power is not measured by amperage alone.” Power is probably the most misunderstood term in our industry. The term “10 Amp” on a power supply is meaningless; you must know the voltage at 10 Amps in order to determine the actual power of your controller. Power is measured in Watts or VA (Volt Amps). Watts (or VA) are the voltage times the current – in other words, when drawing full current, what is the voltage? A unit that has a power level of 130 VA and shows a rating of 10 Amps will only provide 13 Volts at 10 Amps. Many controllers advertise 10 Amps and 24 Volts; this may be true, but is misleading; you can only have one – not both – at the same time. A more accurate way to show the power of a controller would be to say 10 Amps @ 24 Volts; the power then would be 240 VA (or 240 Watts).
What does linear power supply mean?
Linear power supplies in the electronics industry are generally known as “brute force” power supplies. They use a very large power transformer and tend to be very heavy in comparison to switching (or pulse width type) power supplies. Linear power supplies are generally much more reliable at higher current, and do not emit high frequency waves, as do switching type power supplies. The advantage of switching power supplies is that they are much lighter than the brute force linear type supplies.
What are heat sinks?
In all power controllers, heat is generated. As a result, it is necessary to use a system to allow the power components (particularly the power transistors) to have a heat sink to help them keep relatively cool. The power transistors must dissipate the heat that is generated at slow speed. When you are running the controller at high speed, the motor in the engine dissipates the heat that is generated.
“transformer“, “power supply“, “controller“, what’s the difference?
In the early days of model trains, such as the early Lionel trains, the engines ran on A.C. Voltage, therefore calling the controller a “transformer” was correct. The newer engines, however, run on D.C. current; this means you need a power supply that converts the A.C. to D.C. In order to control the speed, you need circuitry that will vary the D.C. voltage. So, strictly speaking, a “power supply” would give you a fixed D.C. voltage, and a “controller” would allow you to vary the D.C. voltage.
Are track clamps important?
The more track sections you have, the more important track clamps become. Electrical resistance can be a very big problem if not kept to an absolute minimum. Using track clamps can be a good method of decreasing resistance. You must, however, allow for the track to shrink and expand with variances in temperature; the longer the track, the more it will shrink or expand. One of the best methods is to solder a “strap” or wire from one track to the other (leave slack to allow for expansion).
Is it possible to use too heavy a gauge of wire?
The simple electrical answer is no. You should, however, use wire that will bend easily and, if used outdoors, it must be UV protected and able to be buried. Generally speaking, the heavier the gauge, the better. Bell wire, phone wire and house-type wire are not well suited for train layouts. The right Romex could be used, but it is very stiff due to being solid copper rather than stranded. As train layouts are demanding more and more power, you should consider using 10 gauge stranded direct-burial wire for this purpose. In some very large layouts, you might even want to run parallel wires to different places on the track. If you must splice the wire, there is no good substitute for soldering, particularly when the splice is out in the weather.