Subject: Re: LED schematics
Date: Thu, 16 Jan 2003 03:28:46 +0000 (UTC)
NNTP-Posting-Date: Thu, 16 Jan 2003 03:28:46 +0000 (UTC)
User-Agent: tin/1.5.14-20020926 ("Soil") (UNIX) (Linux/2.4.20 (i686))
Jim Yanik wrote:
> wrote in
>> Jim Yanik wrote:
>>> email@example.com (kemnurd) wrote in
>>>> I'm looking for a 'home-made' version of a LED flashlight. I would
>>>> like to have 5 blue LED connected to one base, run on batteries. I
>>>> have some electronics backround, but not a lot. hoping to find
>>>> supplies at radio shack...:)
>> IIRC http://www.micrel.com/ have a chip designed specifically to drive
>> LEDs from a battery, stepping up the voltage and regulating the current.
> I bought some LT1932 IC's from DigiKey,they are SOT-23-6,a 6 pin DC-DC
> boost converter with current regulation,can drive 5 LEDs in a row,or two
> rows of 5 LEDs.They only need 5 extra parts to complete the circuit.Check
> out the Linear Technology website for a datasheet.It's a simple
> circuit,just the parts are really small. My first PCB is 15mm diameter.
I may have been thinking of that part.
Though I did do a simple circuit without current regulation (it's a feature
to tell you the battery is failing) that fitted in a space an AAA wide by
IIRC 3 transistors, 1 inductor, 4 resistors, 2 capacitors and an LED.
500Khz boost converter, using the LED as a load without a buffer cap.
I diddn't bother to do a self-oscillating one, as the astable made for
easy setup, with surprisingly low current consumption.
I did try using the inductor as the collector load in one side of the
multivibrator, but it ended up using more current.
PCBs are for wimps, it was made by point-point wiring the components together
with enamelled copper wire, then potting in epoxy.
http://inquisitor.i.am/ | mailto:firstname.lastname@example.org | Ian Stirling.
"An enemy will usually have three courses open to him. Of these he will
select the fourth." -- Helmuth von Moltke