Full vs.Half wave LED's

[sjmiller]

This is an interesting message thread - with a lot of mis-information.

There are those that don't like LEDS because of their brightness and color saturation, that is a preferance.

Fact, using a Kill-O-Watt meter, a string of 100 mini-lights uses 97 watts, a string (depending on color) of 100 LEDS uses between 3 and 4 watts. How can you say that there isn't a cost savings?

An incadescent light will take milliseconds to get up to tempurature, an LED "lag time" is in the nano-second range.

As for the 1/2 wave or full wave rectifier LEDS, full wave is better - lights are on full time and look brighter.

I use both, the 1/2 wave are cheaper and I get them from the Big Box stores. My full wave LEDS are from Creative Displays, they are a better quality, and they work with LOR.

Last year I bought a bunch of the Martha Stewart LEDS from Home Depot - they are total crap. They don't fade and you need a snubber or they stay lite.

If you have part of your display in constant motion - don't use 1/2 wave LEDS there - there will be the 30 hertz flicker - but wait, your TV is updating it's screen at 24 hertz... flicker?

[Surfing4Dough]

sjmiller wrote:

This is an interesting message thread - with a lot of mis-information.

...

Fact, using a Kill-O-Watt meter, a string of 100 mini-lights uses 97 watts, a string (depending on color) of 100 LEDS uses between 3 and 4 watts. How can you say that there isn't a cost savings?
...

The point that I think some are making is that it will take many many years for the cost savings from lower electricity use to exceed the price jump of buying LEDs--Return on Investment (ROI) basically. If basing purchase purely on this, it is a gamble that it may pay off. This is why I mainly buy my LEDs when on sale/clearance. Plus the table tilts when factoring in house electrical upgrades that may be needed.

Over the years, it seems that majority of light strings (LED or incandescent) fail due to cheap wire issues not actual bulb issues. So a LED that lasts a 1000 years doesn't matter when the wire fails in 3. Now I don't know if LED strings wire become less "fragile" or brittle over time since they don't experience as much heating and cooling due to less electrical load on the wire.

All I know is that it sure would be nice if the price of LEDs would come down like we predicted/hoped that they would several years ago, but in these days of ridiculous inflation just the opposite is happening. For example, 60ct strings have now become 50ct strings for the same price (reminds me of the subtle deception of Americans with smaller ice cream containers or cereal boxes).

[Timon]

Old topic but let's bring it to the top of the stack.

I took a totally different approach to driving LED for my HolidayCoro faces and other similar props.

I'm not using a LOR AC controller but instead I'm using a CMB16D-QC. I'm using modified AC half wave strings I got from BigLots!. These came as two 60 LED strings in a box that I got on a sale day for about $8.50 a box. That's 120 LED. The modification is quite easy, you cut out all of the traveler wires leaving you two 30 LED long string. Now for installing and driving them.

First I'm powering the CMB16D-QC from a 48VDC power supply.

I run 15 LED in series and then parallel those strings. Note, you need to put at least a 1 ohm resistor in series with each strings as paralleling LED can cause problems with out that resistor. With 15 LEDs and 48 volts the LED will run at about 16ma which seems to be bright enough for singing faces. If you want them brighter then run 14 LED with a correctly sized resistor so you can run at their rated 20ma.

On faces you going to find many places when you need less than a 15 LED so shorten up the string at needed and select the correct resistor.

I like this much better from a safety point of view. If you use a good 48VDC power supply and make sure it's fully grounded you virtually eliminate any shock issues and you can run in full raining conditions.

Dimming is much better than with the AC controllers although I will say that LOR does need to adjust the PWM curves on the CMB16D-QC. You should be able to dim all the way down to 0 but currently the 1% setting is brighter than it should be. Remember you always sending the LED full voltage just making the pulse very narrow. I plan to call LOR about this and see if they can update the firmware so the dimming will be better.

Have fun.

[Steven]

Timon wrote:

First I'm powering the CMB16D-QC from a 48VDC power supply.

... the 1% setting is brighter than it should be.

That is impressive!

I have also found that 1% is too bright when using a DC board with a 12v RGB ribbon. I'm still waiting for the new firmware with the dimming curves.

[Timon]

I'll post a video soon although it will post on DIYC first.

[yukon]

Not an electrician and I am Budget conscious So I went 100% LED and striclty from Big Box Stores for the last 3 years. Purchased most of my lights from Walgreens and Target and they are probably Half wave.I did have an issue with Fading on certain channels if I overloaded them with to many light strings but that was easily fixed with a snubber of some knid. (Glade air freshner)I have not had to replace any sets of lights yet after 3 seasons but I expect that at some point that will change. I just can't see spending $15-$18 per set when I can but 3 sets for the same price and have plenty of spares to use as replacements. I use Red, Green and Blue and they all work the same for me.

[Timon]

I still wish the diming curves could be changed so the LEDs could dim down to zero.