On 6 Jan 2004 at 7:58, B=FChler, Martin wrote:

> hi bob
> this one looks great, and i think i should be able to get these semis in=
 europe.
> what I'm a bit unsure is the inductor. I'm not sure if I will get someth=
ing similar.
> does this also work with a toroid, or does it have to be a closed one?
> ...and what is the gap for?
> ...if I find a closed core, does size matter?
> does this inductor get warm, or can I use wires with plastic isolation?
> what kind of wire did you use?

Don't use a toroid, you need an inductor with a gap, because the circuit o=
perates in
continuous mode. It has continuous DC in the inductor, and the gap softens=
 the
saturation. The inductor does not get warm unless you run it at maximum cu=
rrent, so you
can use any kind of wire. Here's a link to a fellow's website in Denmark w=
ho built one
and left out the parts he didn't need. His choice of parts was a little fu=
nky. One
modification I made that isn't documented is to feed the chip from the out=
put voltage,
because it has an ~8 volt undervoltage shutoff. By bootstrapping from the =
output it will
run(at reduced output current) down to 6 volts. His stripped-down version =
shows that
modification.

http://dion.swamp.dk/carpower.html

Cheerful regards,

Bob

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