Looking for cheap boost chip 1.5v for LED
- Thread starter ken2400
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mdocod
Flashaholic
the little dorcy 1AAA LED flashlight has one in it 
, not sure how far it can pull down the cells though. Might be cheaper to buy that light for $6 at the store than have something shipped, hard to say though.
, not sure how far it can pull down the cells though. Might be cheaper to buy that light for $6 at the store than have something shipped, hard to say though.
Illum
Flashaholic
the dorcy 1AAA 2nd gen measures off my multimeter at 240ma:green:
since its a DC-DC step up, the LED's not getting 240ma, thats for sure...from the output I'd say its around there
I built this guy from scratch...and I'm out of 150uF electrolytic caps, so I used two 100uF caps:candle:
using a new 1.5V alkaline AA It can boost to 3.3V, sufficient to light up a RX1H luxeon star...at about 100ma
since its a DC-DC step up, the LED's not getting 240ma, thats for sure...from the output I'd say its around there
I built this guy from scratch...and I'm out of 150uF electrolytic caps, so I used two 100uF caps:candle:
using a new 1.5V alkaline AA It can boost to 3.3V, sufficient to light up a RX1H luxeon star...at about 100ma
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Gunner12
Flashaholic
Illum
Flashaholic
unfortunately the coil is the most difficult part of the joulethief, and it has to be homemade because the schematics require it to have 4 wires instead of the usual 2, meaning you'll need a ferrite coil and wound one yourself. none of my homemade inductors as per the joulethief instructions actually gave me a light:green::candle:
TorchBoy
Flashlight Enthusiast
Re: Looking for cheap boost chip 1.5 V for LED
:grouphug: That's sad. Don't give up!
jtr1962
Flashaholic
jtr1962
Flashaholic
It'll start at about 0.65 to 0.70 volts. Once started, it'll work down to about 0.5 volts.
Black Rose
Flashlight Enthusiast
Electronics noob question.
R1 and R2 are resistors, Q1 and Q2 are transistors.
What are C1 and L1?
TigerhawkT3
Flashlight Enthusiast
Hey jtr, is the inductor in that design commercially available, or does it have to be hand-wound like the Joule Thief's? It looks a little more complex, but if it doesn't require any hand-made components, it could be pretty handy.
The simple two transistor schematic that jtr1962 posted is a winner. I have built several drivers using it.
jtr1962
Flashaholic
It's just a standard commercially available inductor. No hand winding required.
jtr1962
Flashaholic
Voltage of C1 doesn't really matter as it sees no more than perhaps 4 volts. Most ceramics are rated at 50V at least.
BTW, with some tweaking and changing of values it's possible to use this circuit to drive far more than one LED. I made a version which powers two strings of 14 LEDs in series from 4.8 volts (4 AA batteries in series). I don't remember what component values I used offhand as that was about 3 years ago. The circuit as shown drives the LED with an average of roughly 20 mA when powered by a AA cell. You can decrease R2 to increase the drive current, and vice versa.
Illum
Flashaholic
well...simple as possible you could go down to two components...but I'd prefer to have filter caps on both the in and out
0.9V- Boost Driver for White LEDs PR4401/4402
All you need to change is the inductor value to get the appropriate current output.
I don't think it gets easier than this, my soldering suck so SOT23 is no good for me because its a SMT component. but so far I haven't been able to find one that has it in the easy TO-220 packages:shakehead:mecry:
minimum startup: 0.9V and could operate between 0.7V and 1.9V at 25C
if the circuit is completed with 10uH inductor + 1 LED Vcc = 1.5V
LED peak Vf [5.8V], mean current [20ma], mean supply current [70ma], efficiency [77%]
these values are from a datasheet I have on the hard drive...I haven't been able to locate the right link to post to this post
EDIT: found the link: http://www.prema.com/pdf/pr4401.pdf
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