Do you think LEDs are a good idea?

I don't think LEDs use alternating current, considering they are very much akin to a diode, which only lets current pass in one direction. If you hit an LED with alternating current, half of the cycle would render the LED dark, instead of just the two points where the wave form crosses 0V.

Thus, an adapter would likely be used to rectify the AC signal into a DC current. No more flickering.

 

LEDs are not akin to diodes. LEDs *are* diodes: Light Emitting Diodes. That's the point. Cheap AC powered LEDs are half-wave only. It's even worse than that, since LEDs have a threshold voltage, much like a zener diode. You have to get above the threshold voltage before an LED conducts and creates light. Normally cheap AC LEDs are wired in series, so that the combined threshold voltages get the operating voltage up close to line voltage. A low operating voltage means a lot of wasted power in passive current control. A high operating voltage means that the LEDs conduct for only a short blip at the top of the sine wave. Either situation is non-ideal.

More expensive LED lamp systems use sophisticated driver circuitry which converts AC to PWM DC, but drivers are expensive and the public buys cheap products. At this point the majority of AC powered LEDs use half wave AC.

Tom

 

There are some industrial LED's available, such as those from Cooper Crouse Hinds, that are totally sealed, explosion proof, with high quality PWM driver circuits. Their purchase cost is breathtaking

 

Bold added for emphasis.

Yep, the cost of buying specialty electronics that can be used 24/7 in the highly flammable operating areas is usually rather stiff. By the time they've designed special housings, had them produced, tested, and certified the price is approaching escape velocity.

 

But they sure do work nice

 

I used to play with mercury in my hand when I was a kid back in the 60's. Then mom would come in and say it's time to put your mercury away, go wash your hands and come eat dinner. Who knew? Good thing I didn't know it was poisonous back then, I might be dead now.

 

Pure liquid mercury is very poor absorbed, so its risk is comparatively low. The vapor is a greater hazard.

Some organic forms of mercury (dimethylmercury and methylmercury) are highly toxic, and nearly completely absorbed.

 

I used to have a test tube of mercury from one of those old style chemistry kits. We used to pour it out because it was cool to watch how it behaved (high surface tension). We would coax it back into the test tube without touching it.

 

> Do you think LEDs are a good idea?

*snicker*
Ah. Yes. A very BIG YES. Especially in automotive use where typically the directionality and near instant illumination are huge benefits. Couple that with longevity, compact size and vibration resistance... duh, yeah.

 

And will bioaccumulate.

But hey, smoking must not be bad either because I knew a lady who smoked and she lived to be 90.

[ame="http://en.wikipedia.org/wiki/Mercury_poisoning"]Mercury poisoning - Wikipedia, the free encyclopedia[/ame]

 

How much mercury vapor can a 2 & 3 YO absorb before it becomes a problem? In my kids play room, 3 of the CFL's decided to POP. I'm not saying they burned out, I'm saying they actually popped, the glass separated from the base. These are in ceiling cans, so they are right overhead too. If they were dropped and broke on the floor, I wouldn't be so concerned, but they popped while the mercury was vaporized, and that has me concerned.