single cell/low component count circuit wanted

[PEU]

I'm finishing my first flashlight (aaa size) in my new lathe and I was thinking of putting a luxeon in it.

I don't care for regulation (at this moment), I just want to fire the LS at about 150/200mA, what simple circuit you suggest?

I've got plenty of inductors, many kinds of transistors, components to build 5 zetex circuits etc etc, but I want this circuit to be powered by a single AAA.

any input apreciated /ubbthreads/images/graemlins/help.gif, I don't want to miss the contest deadline.

Pablo

 

[MrAl]

Hi there Pablo,

Didnt we figure the Zetex 300 circuit would run at
1.5v with reduced output, so 150ma would probably
be obtainable with reasonable current draw.
It's been so long ago i cant remember, but i think
that chip 'works' down to 0.7v so it might be worth
trying.

I do hope you post some pics of the flashlight body, and
after it's lighting too. Must have been pretty interesting
making you're own from (i guess aluminum) stock.
Also, did you have to thread the end for the end cap
or something like that?


Take care,
Al

 

[PEU]

I'll try the zetex circuit Al, the light is like the arc AAA, it does not have a end cap, just two pieces, the head and the body. I sold my PDA with camera yesterday (a new clie TH55 is on the way!) so I'll take the pictures at home the week end.

Thanks

Pablo

 

[MrAl]

Hello again Pablo,

OH i see, so you threaded the top then or what holds it
on?

Oh so you are getting a new small comp, nice. I've
seen a few already but havent gotten one yet.
How much memory does it have and what speed is the
processor?

Take care,
Al

 

[PEU]

yes, I threaded the top.

I purchased this one: TH55


OTOH, I never actually opened the zetex components from digikey, man these are reaaaaaaally tiny, I need a sharper iron...

Are the shottky and the cap really necesary or they are there to rectify thus improving brightness?

Will try /ubbthreads/images/graemlins/thinking.gif

Pablo

 

[MrAl]

Hello again Pablo,

Wow, some price tag :-)
Nice though!

In the past i've made small tips when i didnt feel like
running to the store by either grinding an old 'fat'
tip to a point or threading a steel nail with a die
and grinding a point on the other end. Works ok i guess.

Oh yes, the Schottky and cap are really needed because
of the pulse current to the LED. If you dont use
the Led and cap you run the risk of too high a pulse
current to the Luxeon. People have done this, but
i dont know what kind of life they got out of the
Luxeon when doing this. At 150 or 200ma there will
be less peak current, but a measurement would
be in order. Luxeon spec's 500ma max pulse current
so if you go over that you take the risk.
A quick guess would be that the inductor charges
for 2/3 the time and discharges 1/3 of the time,
so for 150ma average that would only be 450ma peak,
which would be ok. For 200ma average that would be
600ma peak, which would be over the max spec, but
it might run for a long time anyway.
Would be interesting to measure it.

Take care for now,
Al

 

[ViReN]

WARNING : ! .... /ubbthreads/images/graemlins/ooo.gif

This has happened with me TODAY..... /ubbthreads/images/graemlins/frown.gif

I Modified the 2 Transistor Circuit.... adding a Shottky Diode (1Amp) and 2.2 uF Capacator (63V, i could not get voltage rating below this) thinking... that i would get a better o/p .... /ubbthreads/images/graemlins/smile.gif .... and this is what happened....

1) I connected the supply....1.5 V,
2) Added Schottky diode at the o/p end... (+ve)
3) Connected a Capacator.....(With Proper polarity)
4) Connected about 3 parallel LED's.....

And it was expected.... that this will work fine...
but what actually happened was.... just a small flash ... and nothing else /ubbthreads/images/graemlins/ooo.gif ... when i tried to reconnect the led's (remember supply was on all the time ... even though just 1.5 V ... AAA) hmm... again same thing.... /ubbthreads/images/graemlins/thinking.gif

i was thinking.. /ubbthreads/images/graemlins/thinking.gif /ubbthreads/images/graemlins/thinking.gif that circuit was not working as intended... so i removed the added Schottky and Capacator...
connected LED's again... and this time... nothing happened... not even a flash !....
checked with DMM.. what's the o/p .... and it was fine... what could have possibly gone wrong ???

Boy oh Boy.... when i connected another led's .... they were lit (ofcourse without the cap and diode)....
again connected cap... diode.... SAME... Flash... later on... nothing !!!.... /ubbthreads/images/graemlins/rolleyes.gif

I wondered.... /ubbthreads/images/graemlins/poke2.gif and thought.... and a wild thought came in my mind.... are the LED's (6 by now... ) blown OUT ????!!!!!!................ /ubbthreads/images/graemlins/ohgeez.gif /ubbthreads/images/graemlins/ohgeez.gif /ubbthreads/images/graemlins/ohgeez.gif

YES THEY WERE !~!~!~!~!~!~!~!~!~!~!~! /ubbthreads/images/graemlins/banghead.gif /ubbthreads/images/graemlins/banghead.gif /ubbthreads/images/graemlins/banghead.gif /ubbthreads/images/graemlins/banghead.gif

Guys... reading this DONT LAUGH... its an Achievement... blowing up to 3 LED's using a AAA cell... and a fine piece of Circuitry... /ubbthreads/images/graemlins/cool.gif

Later on... i figured out that while the supply was on .... the capacator charges... (to the voltage peak's) .... and when we connect LED's ... that Flash... tells you about BLOWING LED's !.... /ubbthreads/images/graemlins/clap.gif

I Learnt the hard way.... but... for you guys (who might already know this... may be .. may not be)... ....

NEVER EVER CONNECT SUPPLY BEFORE CONNECTING LED'S TO THE INDUCTOR BOOST CIRCUIT ESPECIALLY WHEN SCHOTTKY DIODE AND CAPACATOR ARE USED... AT THE OUTPUT END

Later on when i connected the things... with the LED's ... the brightness was increased... and ofcourse.. that pinkish.. blue tinge ... on the beam was gone...

thankfully... the LED's that i blew up... were cheap ones ($0.1 .. a piece) .... and not the Nichia's ($2 a piece... which i procured recently) ....

Hope this will help fellow CPF Members & those who build their circuits for the first time.... ... (i think.... the transistor circuit is a good one to start with /ubbthreads/images/graemlins/smile.gif )....

Mr Al .... I have a request for you .. will post in the proper thread heading...

Thanks & Regards,
ViReN