Power my loop box LEDs with 18 volt?

[GibsonGM]

Earned a "like" for that, Eric.  I hate tossing power for no reason (that is why I 'hate' seeing regulators inside circuits, when their 'real place' is to condition power to run the whole thing).   

It's not a conservation issue....mostly for me it is my Maine Yankee background, 'simply wasteful', and also these things feel so clumsy....like trying to find a heater supply when it is EASY to get 120V for a tube, but NOT easy to get the 12V for the heater, ha ha...and burning up volts for heat that won't be wanted....that feel plain awkward...

[duck_arse]

..... suggesting (too subtly -- my fault) that there are some unnecessarily complex ways to drive the LED .....

people! use the sledgehammer, that's what it's there for.

here is two ways to constant current source a led, very simple, both include a resistor, one appears in the orange squeezer.

[GibsonGM]

That costs money, Duck     

[EBK]

Current source? Check. That sledgehammer doesn't really save on power though does it?

[PRR]

I see NO advantage in a "regulated current source" when you have fairly stable voltage.

Sledge-hammer is overkill. Use a rock. In electronics, resistors are our rocks.

Power dissipation is the SAME.

To make Mike and other cheap Yankees (I'm living north of him, so me too) happy... you have to exchange voltage for current. This is easy. Run a 18V 2mA motor to turn a 2V 20mA generator. If you can buy these machines with high efficiency, the result is efficient voltage/current exchange.

Sadly the losses in a $2 motor exceed the total power demanded so efficiency will be worse than a rock resistor. There may be a $900 mini-motor, but if I had $900 I would not be sweating a few mA of LED power.

The other way is to flow 18V 2mA into a reactance for a while, then kick-back to a lower voltage at higher current. Such DC-DC converters exist, and increasingly inexpensive. Joule-Thief is a simple device, much more efficient converters exist. Most however are voltage-oriented output, and we would like current-oriented.

But really. We usually want 25-200+ Watts of light and about the same of amplifiers to play in. Why are we even thinking about a third-Watt of "waste" power to feed an LED?

[EBK]

Why are we even thinking about a third-Watt of "waste" power to feed an LED?

I already answered that one.  For fun, or as an academic exercise.

If you take the question too seriously, you stop at the "right" answers and waste an opportunity for learning.

[duck_arse]

rocks or sledgehammers - take your pick.

[bool]

I'd pick a fireman axe..

[GibsonGM]

To make Mike and other cheap Yankees (I'm living north of him, so me too) happy...

VERY OT:
You're north of Strong?  I'm on a big hill over by Rangeley.   60mph winds last night/this morning.  Lost 1 big wooden storm and a single-sash window actually popped out of my house, leading to sudden out of bed syndrome and lightning-quick reaction before all the heat got out...I'm glad that I didn't partake too merrily to be functional, LOL!

[PRR]

> You're north of Strong? 

No, I'm lost.

I'm along the coast, and actually (when I saw how far up Rangeley is, well north of Rumsford) about 60 miles south of your latitude.

[GibsonGM]

It happens!  Cold there, too, just different...wife is from Calais, and the moist air/wind can be BRUTAL. 

I surmise that exposure is exposure...to either the sea or the mountains....stay warm my friend!! Now you know what I'm on the forum 25x per day, LOL....not a lot of humans here....