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 Post subject: Re: Homemade LED and portable Refractometer lamp
PostPosted: Thu Feb 07, 2013 3:45 am 
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Or if you have a 12 volt wall wart you wish to use, then put four of the xenon lamps in series.


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 Post subject: Re: Homemade LED and portable Refractometer lamp
PostPosted: Thu Feb 07, 2013 4:36 am 
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Thanks for the help, Massa. :D

So it's not as easy as soldering a certain resistor in between the 12v input and the 3v xenon bulb?


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 Post subject: Re: Homemade LED and portable Refractometer lamp
PostPosted: Thu Feb 07, 2013 8:32 am 
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Hi Tim,

you found nice 590nm led, good viewing angle.
They run with 12v as you need, and they are more expensive than the "standard led requiring resistor" because there are 4 leds and a resistor inside.
So, for question 1 you are right.

Question 2: I will prefer the led type you found.

About spectroscopy light, sometimes I use white led light: it fit for blue region evaluation.
My opinion, use a switch for bulb light or white led light.

About to reduce voltage from 12v to 3v, the correct way is using a stabilizer integrated circuit:

http://www.datasheetcatalog.org/datashe ... e3pl3y.pdf

By the way, it will works also with a (high wattage) series resistor.


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 Post subject: Re: Homemade LED and portable Refractometer lamp
PostPosted: Thu Feb 07, 2013 1:21 pm 
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Quote:
So it's not as easy as soldering a certain resistor in between the 12v input and the 3v xenon bulb?


That will work but is a very crude and inelegant way of doing it. Even using an IC regulator as above you will waste ,as heat three quarters of the power. Just get the right size power supply. Not a moon shot.


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