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Author Topic: LED's - Driving a 4-volt LED from 1.5-volts.  (Read 2403 times)

OMK

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LED's - Driving a 4-volt LED from 1.5-volts.
« on: December 01, 2006, 01:19:20 AM »

Some time ago I happened upon a circuit that powers a 4-volt LED from a single 1.5-volt cell. It even works off one of those tiny button cells. So if you're super-brilliant, like me, and fairly modest, like me, you might be thinking: "Hmm... now I can cram my white and blue LEDs in that cramped space after all.".
Or words to that effect.

Take a butcher's at...

http://www.keirle8122.fsnet.co.uk/non-gdts/joule/joule.htm
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Doc

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Re: Driving a 4-volt LED from 1.5-volts.
« Reply #1 on: December 01, 2006, 11:54:49 AM »

This type of DC to DC voltage converter is used in a number of ways/devices.  The resulting voltage 'pulses' can get to ridiculously high levels (ouch!) so don't get too 'stupid' with it ('Tasers', shock-prods, etc.).  But not with the components used, thank goodness!  Wish I'da thought of it...
 - 'Doc
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funtimefrankie

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LEDs
« Reply #2 on: December 01, 2006, 08:14:16 PM »

Just bought a set of LED christmas lights from "the Range" For 1.99 you get 20 small LEDs a battery box with the switch and resistor.
They operate off 2 AAs.
They have all red, all green, all amber or mixed. Bummer is no white.
I hope to find a use for them soon.....
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Microyacht

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LEDs
« Reply #3 on: December 01, 2006, 08:56:58 PM »

Quote
Just bought a set of LED christmas lights from "the Range" For 1.99 you get 20 small LEDs a battery box with the switch and resistor.
They operate off 2 AAs.
They have all red, all green, all amber or mixed. Bummer is no white.
I hope to find a use for them soon.....

 . . . . Sounds just right for running from stem up to the mast head or funnel etc then back down to the stern, to decorate your favorite craft when it's in the lounge for Christmas! Who needs a tree?
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OMK

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Re: LEDs
« Reply #4 on: December 01, 2006, 10:11:13 PM »

Bummer is no white.

The clue was in the fact that they're powered from just two cells.
White and blue need at least three.
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RickF

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Re: LEDs
« Reply #5 on: December 02, 2006, 12:40:13 AM »

Wilkinsons have them in blue and white (as well as red, green and yellow - but not mixed) at 2.99.

Rick
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tigertiger

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Re: LEDs
« Reply #6 on: December 02, 2006, 07:34:35 AM »

If memory serves, but I am getting older :-[.

Blue and white are 3v.

red, yellow, green, are 2v.

So maybe explain colour schemes

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OMK

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Re: Driving a 4-volt LED from 1.5-volts.
« Reply #7 on: December 02, 2006, 05:24:24 PM »

Me too.
And have you ever seen the insides of one of those Tasers'? More to the point, have you seen what's NOT in 'em? There's hardly anything there. Just a battery, a couple coils and caps...
Fun! For just a few measly dollars you can zap each other 'til the cows come home.
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cbr900

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Re: Driving a 4-volt LED from 1.5-volts.
« Reply #8 on: December 03, 2006, 01:30:21 PM »

Could be very handy for lighting in a model that is border line on top weight............




Roy
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Aston

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Re: LED's - Driving a 4-volt LED from 1.5-volts.
« Reply #9 on: December 04, 2006, 09:00:33 PM »

if you want a ridiculously low priced source of LED's in all sizes, colours, and even flashing  :o look on ebay for a seller called amigoofchina,  he's based in Hong Kong  ;D but gives an excellent service, and does packs in various (large) amounts,and ALWAYS includes free resistors, one per LED to allow them to be run from a 12v source.   cost per light is dead cheap.

                                                                                                   cost        shipping        total       per LED
eg,  100 x 5mm White Flash 5000 mcd LED Bulb inc Free Resistors         12.99      3.50            16.49   16.5 pence !
       50 x 3mm Blue Flash LED Light Alarm with Free Resistors                  4.99      2.00             6.99      7 pence
       50 x 3mm Green 5000 mcd LED Bulb with Lamp Free Resistors          2.99     2.00             4.99       5 pence

I and a few of our club members have used him several times, and a feedback of over 3500 speaks for itself ( if you know ebay).

try this link to his ebay shop if you are interested,  I have no connection ( Hong Kong is a long way ) other that as a very happy customer  :D :D :D

http://stores.ebay.co.uk/Amigo-Of-China

Regards

Aston
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GreeboTheCat

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Re: LED's - Driving a 4-volt LED from 1.5-volts.
« Reply #10 on: April 17, 2007, 02:51:19 PM »

Have just ordered some Blue LEDs from this chappie in Hong Kong and now I'm looking for a REEAALLY simple circuit to flash then on and off. I want to achieve that lovely blue flashing light effect that we all know and love! :'(
Has anybody got such a circuit?
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OMK

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Re: LED's - Driving a 4-volt LED from 1.5-volts.
« Reply #11 on: April 17, 2007, 04:20:41 PM »

Any simple two-transistor oscillator will do the job. Even the ubiquitous '555 timer chip.
See how you get on with this...

http://www.keirle8122.fsnet.co.uk/non-gdts/beacon/beacon.htm

How many blue LEDs do you need flashing at the same time, anyway? The '555 can only output 0.2 Amp max. That's about enough to drive about nine or ten blue's (theoretically). If you need more than that amount, then you'll need to add a beefy transistor (or mosfet) at pin #3.
Otherwise, if you only need to flash, say, just one or two LEDs, then the whole she-bang can be shoe-horned on a scrap of matrixboard, probably no bigger than one inch square.
In order to power it you can rob the juice from your receiver battery. Or even a separate 9v PP3.
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