Where I work we sell LED Christmas lights by the millions. Minis, C-7, C-9 etc. There are single diode, triple diode, but all the C-9s are 7 watts with either 1 or 3 diodes. Can someone explain all of this. And pretend I am a 12 year old... hehe

Well, Dave, I can't comment on the designations of C-7, C-9, etc, but I can give an entry-level course in LEDs. Plugged into 120VAC, LEDs would be scorched in milliseconds. Three operations have to occur for LEDs to survive with a 120VAC power supply. First, the voltage has to be stepped down, usually to around 3-6VAC (easier to do with AC than DC). Then that voltage has to be rectified to, say, 3VDC.

However, LEDs' capacity is not rated by voltage but by current, typically something like 65ma (.065 amp). So most LEDs have dropping resistors to limit the current (by way of the voltage - remember that E=IR - and LEDs have little native resistance in the "forward" - so the dropping resistor limits the current flow - they are diodes, so reverse voltage rarely hurts them since current can't flow). But in the "forward" direction (where they light up), too much current can fry them instantaneously, hence the resistors to limit current.

Now, an alternative is to limit voltage so that the LED's internal resistance will be sufficient to limit current flow.

This would mean the the DC voltage would be limited to around 1.5VDC, which most LEDs can handle in their native phase, meaning that dropping resistors are unnecessary.

I've not heard the term "single" or "triple" diode used in quite this way, but there are LEDs that are "double" diodes: Pass current one direction, and the LED lights green. Pass it in the opposite direction, and it lights red. Apply alternating current, and it lights both red and green, which combined, produces yellow or amber.


If you're not yet thoroughly confused, let me know, and I'll muddy things further...

Yes thank you Rusty very helpful and you accurately corrected me. Then incandescent lights are 7w the LEDs are .065W.

Still would like a little more imput on this 2 or 3 diode deal.

Dave, do you have a link to a website where you've seen the C-7, C-9, etc., designation (LEDs are usually designated by their diameter in mm), and that sounds like that's what the "C-7" may mean.

Well Rusty you are probably correct, however, we sell direct replacements for mini-lights, C-7 and C-9 incandesent. So we call them C-7 lEDs and C-9 LEDs because this is what the customer understands.

I work for Display Sales Inc. www.displaysales.com You can go to the online catalog and see what I mean

Click Here

Dave: I buy mine from Superbrights LEDS (http://www.superbrightleds.com/led_prods.htm) and I suspect the reference you have is to the number of led's in the assembly. I know of no 7w led's but they can make that wattage by arranging any number of individual led's into an array and a socket type. My recent purchase was a set of white and amber 3 bulb surface mounts that replaced my aisle lights. The operate on 12 volts and require no additional resistors or work. Just wire them in and they work.
Tom

Many LEDs (like those for automotive or marine use) now have the needed dropping resistors packaged with the LEDs so thay can be connected directly to 12VDC.

Could I replace all the lights in the overhead lights inside my Regal with leds? Would I have to buy some extra equipment to deal with the lower amps needed by leds? What about replacing the tail lights and brake lights and running lights? I've heard something about problems with turn signal flashers. Thanks

Yes you can replace the inside lights easily - they make direct replacements with the proper socket - threaded, bayonet etc. Just compare the pictures with yours. You need no special power modifications. You can run led's on otherwise dead batteries and all you see is a much reduced load on your coach batteries. As for the turn signals - they also make an electronic flasher that plugs right into the existing socket. The use of led's (including new applications for headlights) is reducing the size requirements for alternators. In the future you will see vast improvements in lighting and equipment that will result in better light for almost no drain on the batteries.
You can call them as well and they will work out the proper led's for your use.
Tom

Tom is right on - with the replacement flasher, make sure it can handle LEDs and incandescents if you don't replace everything at once.