Hi all, before this conversation goes off the rails, LEDs (Light Emitting Diodes) require DC voltage in order to operate and require the correct polarity. Meaning if you wire the positive and negative leads in reverse, the LED will not emit, fortunately it will not burn it out. LEDs typically need 3volts dc in order to emit light. Anything less - nothing happens. Any voltage above the threshold will cause the LED to emit - this happens with a "flash", voltage drops off, the supply charges it back up and "flash" again. This happens so fast we cannot see it. Unfortunately this "flashing" also creates heat which must be dissipated. If you do not have some sort of power limiter, such as a properly sized resistor, the LED will happily flash, build up heat, get too hot and burn itself out. This will happen in about a second where you will see a bright "flash" and then its dead. Same thing happens when you put in more dc voltage than the LED can handle.
If you look at many of the Evans Design products, they provide the proper resistors and power rectifiers for your particular application. If you have the proper power source, you may only need the LED and a resistor. Batteries self limit their power output so often do not require resistors between the LED.
Vendors of strip lighting have a completed package. Plug it in, turn it on, it lights, you do not need to know how it works, unless of course you want to take them apart. The strip lights I use are the 12volt dc variety. They include the power rectifier which changes the wall 110 ac to 12v dc. The strips are made to be cut apart and reconnected as needed. Usually there are sections of 3 LEDs and their resistors making up the strip with places to cut indicated on the strips. We can use that design to our advantage, by cutting up the strips into sections. There are roughly 6 sections per foot. A 15 foot roll gives me 90 LEDs for lighting purposes - no more than 25 cents per light. Of course you will use these where you cannot see the strip and wires - only the light emitted.
Lastly, will 12 volt LEDs work on 12 volt ac power. There are plenty of videos out there showing people who have done this, so it does work, but it is not necessarily a good idea. Remember we think about alternating current as a wave, in our case moving between +12 volts and -12 volts. We already know the LEDs will not light at negative polarity. We also know the LEDs need a minimum voltage to emit. For argument sake lets assume this is a range from 3 volts to 12 volts and then back down to 3. This should tell you what you will observe is the LED going from off to dim to bright to dim and them off again 60 times per second. Its going to be off more than half the time. Most likely you will see this as a flicker. There is also some thought that the continuous cycling applied to the LED puts stress on the device and leads to early failure. Just use the proper dc source for your LEDs.
My opinion - I prefer to isolate my accessories from my track power, so I use separate transformers. Its not much of an issue if running transformer control, but it could be running DCS.
