regulators...what a waste of power *Moved to Electronics*

[Badbeams3]

Ok, so you love regulators...but...they increase power used dramaticacy (Doug, help)
they suck power used comparativly...if the batt voltage is correct,geven the goal...what for? A Light wave 20000 ....will it not be brighter than a Newbeam after ten hours for example...the new beam with new batts?

Have fun tearing me apart...espesulaly you Doug!

 

[WaltH]

Ken Ken Ken,
You gotta love the constant output a regulated light gives you. To be able to count on it for a given amount of time is wonderful. And in the case of the newbeam, when it begins to dim, it let's you know to put new batteries in. I recommend you buy a newbeam and give it a try. 31 bucks well spent.

BTW, we're still enjoying the ZZZ-lite you got for us a year or so ago. Thanks again.

 

[**DONOTDELETE**]

Hi,
I,m a big believer in converters and regulators (they're not exactly the same thing, maybe they should be called regulated converters, that's more accurate).
Most converters operate at about 90% conversion efficiency. Thats not a huge waste of power. A converter will give you full light to the bitter end, when those pooped batts would otherwise just make the LED glimmer. Also a lot of flashlights use a resisroe to limit current, talk about waste. Also, because of the very "touchy" nature of the E-I curve for LEDs, the output falls dramaticly when the batt voltage drops just a few dozen millivolts. Dude, get with the times...converters are the way to go, at least in a non-toy flashlight.

 

[rlhess]

There are at least four ways to power an LED.

(1) Connect it directly to the battery. In this case, you're relying on the internal impedance of the LED and battery to limit the current. As the battery voltage falls, the light falls.

(2) Use a resistor to limit the current in (1) above. This wastes power in the resistor and as the battery voltage falls, the light output falls.

A note on this. Since there is a very steep curve of current vs. voltage for an LED the LED light output will fall faster than an incandescent. One test I did in an Inova X5 and a Brinkmann LX with two sets of batteries:

The LX was 13% lower, the X5 was 33% lower light output.

(3) Replace the resistor with a current source. It will waste battery energy as heat when the batteries are fresh, but yu can get more "headroom" between the LED and the battery new voltage without risking blowing the LED. Then as the battery voltage drops the LED remains as bright and less energy is wasted.

(4) use a switchmode current regularor. This uses an inverter type circuit and is 90% (or so) efficient. There are many sub configurations of that and it's an area I'm not an expert in.

The above-noted fault of LED lights makes me want to see them regulated...but I can't imagine what regulators could do for incandescent as well.

Cheers,

Richard

 

[WarrenI]

Yes, in theory a regulator will waste a small amount of energy. But, a resistor also has this same problem. Think of it this way, a regulator is a smart resistor...

In simple illustration, if you needed 4 volts to a LED, you would build it with 3 cells (4.5 volts) and place a resistor in series with the circuit so that it waste 0.5 volt. This would give you 4 volts. At 75% battery power (3.375 volts), the resistor will still absorb something like 0.375 volts, but would deliver about 3 volts to the LED {ie. 3.375 - 0.375 = 3.0 volts)...

If you were using a regulator, at 4.5 volts, the regulator would be absorbing the same 0.5 volts to produce 4.0 volts at the LED. But, when the batteries are at 75%, the regulator effectively shut down as it senses that it is under the cap voltage. In this state, will absorb something less than 0.02 volts. Therefore your voltage available to the LED would be something like 3.373 volts (ie. 3.375 - 0.02 = 3.373 volts)...

A regulated circuit's calculated break point for full brightness would be around 88-89% of battery power. After this, it will dim, but still would be much brighter for the remainder of it's battery life. A regulator waste much less energy as the supplied power source degrades. A resistor waste the proportionate amount of energy throughout the life of the power source...

 

[Darell]

Great stuff.... for the electronics forum.

Find this thread here: http://www.candlepowerforums.com/cgi-bin/ultimatebb.cgi?ubb=get_topic&f=6&t=000420