Lasersaber strikes again. A joule thief king ?

[TinselKoala]

https://www.sparkfun.com/products/9768

https://www.sparkfun.com/datasheets/Sensors/Imaging/TSL235R-LF.pdf

http://www.youtube.com/watch?v=1Kzf7S-pOEM

[Farmhand]

@d3x0r: I have built a hand cranked generator from a stepper motor http://www.overunity.com/13639/hand-cranked-stepper-motor-as-a-generator/msg365643/#msg365643. And now I know what I can do with it. Together with LaserSaber's latest low power circuit it could be used to charge the cap quickly to get some light.

@Farmhand: you are right that LEDs are incredibly bright when driven with nominal power. But for some applications (like a night light or just a novelty item) glowing LEDs can be nice.

I got some MCP1623T and MCP1640BT voltage regulators (from 0.8 Volt are boosted to 3.3 Volt) and will try a LED driven with a 1.5 AA battery, but the LED will be driven with nominal power (some 30 mA at 3.3 Volt), which should give 6 lumen with the LEDs I have got. The two booster ICs cost less than 50 cent each and need two caps and a 10 µH coil. The efficiency of the booster ICs is 70% to 85% at what I want to do. This is nothing new, but I want to have a hands on comparison of LED brightness with Joule Thief type circuits. I agree that LED brightness is often over estimated by Joule Thief enthusiasts (like myself).

Greetings, Conrad

Yes I have to agree that dimmed LED's are useful as are glowing ones I have some ornaments with glowing LED's myself, also flashing LED's are cool as well especially as indicator lights to tell if something is operating or just to save power and extend run times for nightlights ext.

But we must remember every now and then to re-calibrate our eyes if we don't have appropriate meters, we can do that by blinding ourselves with a single properly driven 5 mm LED, or by doing simple light on the wall comparisons with the properly driven LED.

I have a few things that light the LED properly, one is a fake pistol cigarette lighter with an LED laser sight mock up, it's very bright.

The point I want to make is a competition to see how long we can glow LED's for doesn't really serve any purpose. It's the efficiency of electricity to light that is important.

We can dim LED's by reducing current with uninterrupted DC, or we can reduce the time the LED is on by using pulses, both ways reduce the total light emitted, but the pulsing can keep the LED bright while flashing. Just because the flashing is not visible to our eyes and the flashing is the same "brightness" as the properly driven LED does not mean that the pulsed LED is outputting the same "total amount" of light as the "constantly on" one.

Power input/output is not always related to brightness, but it is related to total light output.

Given the same conversion efficiency for pulsed and continuous DC LED lighting circuits the one with the most power input (staying with design limits) will output the most total light. That's what I think.

.

Brightness and total light output are as different as Power and Energy.

Brightness is the rate of light output. Basically.

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[SkyWatcher123]

Hi folks, well for practical purposes, if a light is not blinking perceptibly and lights up a room just the same as plugged in to the wall, then it fulfills the purpose.
Same as video frame rate, if we can watch the movie just fine without flicker, then it does the job of giving us a fluid video to watch.
As far as more total light being output, doesn't really matter to me, as long as the light can allow humans to see a room and the stuff in it properly.
peace love light

[Pirate88179]

Hi folks, well for practical purposes, if a light is not blinking perceptibly and lights up a room just the same as plugged in to the wall, then it fulfills the purpose.
Same as video frame rate, if we can watch the movie just fine without flicker, then it does the job of giving us a fluid video to watch.
As far as more total light being output, doesn't really matter to me, as long as the light can allow humans to see a room and the stuff in it properly.
peace love light

Well said.

Bill

[d3x0r]

I dunno LEDs are peculair things with joule thieves... I found that voltage was cheap to get, it's current that's the limiting factor... but LEDs are good because no matter how many in series you put, they draw the same current... so building up a high voltage to light LEDs in a long chain was really easy and seemed to take less input current than the total multiple of voltage gained... something like OUBrads just posted...


but LEDs in quantites of 1000 begin to get expensive... so if I wanted to build a 1500V joule theif for 20mA output it begins to be very expensive