Audioguru, as I'm sure you know, the LM317 can be used as a current source, but your power dissipation argument still stands. The switch-mode current source is the weapon of choice.audioguru said:Hi Chiba,
The LM317 linear regulator will waste more power than the LED uses.
Its fixed output voltage will overdrive the LED's current as the LED heats-up. If the torch is left in the sunshine in summer, the LED current will be so high it might melt. In the winter, it won't be very bright.
A switch-mode supply with current feedback is stable and is much more efficient. :lol:
Someone Electro said:I seen an tiny circuit that acts as an constant curent source. and can run an white LED from an single button batery.It can squize the LAST volts out of baterys.
But thats for an litle LED but i think whith a bit of tweaking and a biger transistor it cod run that 1W big ass LED.
mstechca said::lol: :lol: :lol: :lol: :lol: :lol: :lol: :lol: :lol: :lol: :lol: :lol: :lol: :lol: :lol: :lol: :lol: :lol: :lol: :lol:
Zach, Have you ever thought of using a RESISTOR and connecting it in series with the LED? It is by far, the most simplest fixed brightness control you could make, and it costs you under a quarter! Or you can go fancy, and turn the resistor into a potentiometer for a few quarters more.
zachtheterrible said:Had you read further, you would have come across my saying that I don't need a resistor in series with the LED, seeing as there is not enough current to damage it :lol:
Hi Zach,zachtheterrible said:I don't need a resistor in series with the LED, seeing as there is not enough current to damage it.
zachtheterrible said:have you taken the time to read the thread? Because i explicitely said that i want something to regulate the current, so as for the LED to remain at the same level of brightness as the battery voltage drops :lol:
I also want something nice and efficient, i don't consider a resistor to be all too efficient :lol:
Had you read further, you would have come across my saying that I don't need a resistor in series with the LED, seeing as there is not enough current to damage it :lol:
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