Question on LEDs and power supply

Chances are they have resistors and diodes if they're something like the Evan's Designs models.  If they don't have the protection diodes, eventually they may fail.  I was losing them in locomotives early on until I realized that they were getting reverse voltage in excess of their ratings.  That lasted for months and then died.

Nice Tabletop Layout and also good photography.

Thanks Hugh,

John,  I bought one of these gizmos off ebay.  AC in and DC out with a variable output.  I need to get a couple more as I think I am going to run quite a few LEDs in the future.

The LEDs I have, have the resistor installed already, but no diode.

As long as you know you won't have reverse voltage on them, you don't have to worry about diodes.  It's only if they have AC on them.

@ tmack ,,   like your vid with the kids.  thats what its all about. ac will eventually take its toll on the leds.   i also use the same "gizmos" as you. its dc output so, no problems  they work fine as i like the variable output. i use them on my modified carnival stuff to set the animation at the speed i want, or to get light levels to my liking.  MERRY CHRISTMAS to all !!

If you drive them directly from a transformer, I'd insert a diode in series with either the power or common lead to the transformer, your LED's will thank me.

I should add,  at the price of these "GISMOS"  its well worth it as it saves the hassle of ordering parts, assembly, yada,yada,  makes for an easy setup.  order from japan  free shipping.

Do you have a URL for this supply?  What's the specifications and price?

John,

This is the best I can do.  $7.99 FREE SHIPPING Delivery was pretty quick too for coming from Asia.

http://www.ebay.com/itm/LM317-...;hash=item2308ccaed5

Input: DC or AC 4V-30V 

Output: DC 2.5V-27V 1A

Step-down converter

@ grj.  got mine off e-bay  $17.50  free shipping.   sku-155001 from electronics-salon   they are always up on the bay.  i paid 19.99 when i bought mine.  [hong kong]  2 weeks.

How does one adjust the voltage, I see no voltage adjustment.  Other than that, it looks like a useful supply.  There is no specifications on the eBay page, you must have to buy on faith.

John,

For 8 bucks, yes I bought one on faith ,  I'll hook it up tonight or tomorrow.  I think the screw on the blue part is the adjustment.

-Ted

I didn't notice the pot, that's obviously the adjustment.  That's pretty handy for $8. I may try to pick up a couple.  I think I'll offer him $6.

tmacks  unit is fine for leds  1amp  for 8 bucks. good..  i wanted/needed a little more amps.   either is good if you know  what tour needs are

What's a bunch? 

As you know some 12V LEDs are just a single 2V or 3V LED with a built-in resistor to make it convenient to hook up to 12V DC.  This means maybe 80% of the power is wasted in that resistor.  Since this is not an automotive application where you are stuck with a 12V DC source, and you are buying one or more voltage regulator(s) anyway perhaps it makes sense to turn the problem around.  That is, LEDs have become so inexpensive that I wonder if you might be better off choosing different LEDs, wiring configuration (series vs. parallel) and regulator which might give you more flexibility, double or triple available power (more LEDs), and save some $.  But if a "bunch" is just a few, then never mind! 

I buy lots of the LED strips, those happen to be the exception that proves the rule!   I get 300 LED's for $8-9, so that ends up being about 3 cents an LED, and the 100 resistors are tossed in free.

I really do appreciate all the suggestions. I have a job that takes up much of my time.  I still have two young kids at home and they are in sports and other activities. So time is a premium.  I don't mind buying LEDs that are pre-made up.

Also some of the answers I get in this section are very cryptic and not helpful in laymans terms.  At this point in my life I'm not trying to learn a new trade.

Great Ending and Merry Christmas.

When you do get feeling like a 'do it yourselfer' though, keep this site for your files.

http://www.jcstudiosinc.com/Bl...=896&categoryId=

Hugh

Thanks Hugh,  maybe at some point I might venture into that.

Here is a picture with the Step down converter installed.  I run the power from the transformer to a toggle switch, then to the step down converter and distribute the power to LEDs via the punch down block.

Turn the screw on the POT clockwise to increase the DC voltage and counterclockwise to decrease.