Lasersaber strikes again. A joule thief king ?

[Farmhand]

The brightness of the LED's on video is deceptive. If I look directly at a properly driven 5 mm bright LED it has a temprary blinding effect and a small green dot with a purple circumference remains in my vision for some time.

In my opinion we want to drive the LED's to deliver similar or at least usable light levels efficiently.

The looper "tag" is misleading it gives the impression that the devices are self powering when in fact they are just using a very small power draw to show LED's partially driven, either time wise or power wise as well.

Take the low powered LED "looper" light and read a book by it or look for something in the pitch dark with it.

My garden lights drive the LED's to good brightness, it takes power to do that, all we can hope for is better efficiency, or using less power for less light output.

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[conradelektro]

Ya; but before I blew up my NTE47's I had a hand-crank lantern, and attaching it to a 3300uF cap takes only a few turns to charge to 9 volts....


Daniel Nune'z hand crank demonstration...
https://www.youtube.com/watch?v=Z4mTA794U4E  (for instance) I think he's using a similar driver....  no idea how big his cap is...


Oh; but ya  mine only runs for seconds... using the oroiginal lighs from the lantern; which IS longer than they run directly on the generator....

@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

[SkyWatcher123]

Hi folks, Hi conrad, i know what you mean about perception of light output.
Though when using a sensor like that from a solar garden led light, it can be fairly accurate when using an off the shelf, non-modified led bulb.
I built a joule thief, ferrite flyback core with secondary coil (1.65 watt input) that gives around 147 lumens per watt from a non-modified, 6 watt ecosmart led bulb, rated at 450 lumens.
147 lumens per watt, is almost double the stock 75 watts per lumen rating.
Soo, if we apply this to one of these bulbs, http://www.amazon.com/G7-Power-Vintage-3-6-Watt-Replacement/dp/B00GIOXBBM/ref=pd_sim_hi_5?ie=UTF8&refRID=03WSVN1WD4ANP9EZ8RZD
Then at 138 lumens per watt stock output, we can achieve around 276 lumens per watt with the joule thief secondary style setup, maybe.
Will have to buy a bulb to find out, wheres santa, hehe.

peace love light

[MarkE]

Hi folks, Hi conrad, i know what you mean about perception of light output.
Though when using a sensor like that from a solar garden led light, it can be fairly accurate when using an off the shelf, non-modified led bulb.
I built a joule thief, ferrite flyback core with secondary coil (1.65 watt input) that gives around 147 lumens per watt from a non-modified, 6 watt ecosmart led bulb, rated at 450 lumens.
147 lumens per watt, is almost double the stock 75 watts per lumen rating.
Soo, if we apply this to one of these bulbs, http://www.amazon.com/G7-Power-Vintage-3-6-Watt-Replacement/dp/B00GIOXBBM/ref=pd_sim_hi_5?ie=UTF8&refRID=03WSVN1WD4ANP9EZ8RZD
Then at 138 lumens per watt stock output, we can achieve around 276 lumens per watt with the joule thief secondary style setup, maybe.
Will have to buy a bulb to find out, wheres santa, hehe.

peace love light

How did you measure the total light output?  That's not an easy thing to do without specialized equipment. 

[SkyWatcher123]

Hi marke, as said, i used a photoresistor from a solar garden led light.
Set meter to kilo-ohms and placed sensor in same spot on non-modified 6 watt-450 lumen ecosmart led bulb.
Stock output from grid power, bulb shows 1.53 kohm on photoresistor.
Using joule thief with secondary coil circuit, shows 2.83 kohm on photoresistor.
That works out to around 54 percent of the grid powered output, which is around 243 lumens or 147 lumens per watt at 1.65 watt input.
The light that is radiated from this lamp is definitely indicative of 243 lumens to my eyes.
It is every bit as bright as a 25 watt incandescent bulb.
peace love light