How best to get 3.5 volts from 12 volt source?

[lotsa luck]

One thing I have found odd about this topic on this forum. It has generated all very good responses from "chip makers". I posted the same question up on three electronic forums and got crap for help. Even offered up a bribe of one of the LED's for the correct cicuit, with nothing good to come of it.

Good groups are few and far between.

Thanks again guys.

P.S.
I recieved two new LED types from the company today that were custom built to my spec at no charge for the R&D work. To bad they are asain, but the only US competitor that has anything even close, would not even discuss anything custom. I asked them in an email on Friday and have the parts today.

[enauman]

3 terminal Linear voltage regulators would be the simplest way to achive your goal. National's LM317HVK is a good choice. The only drawback is that they will dissapate the difference in the power input Vs. the power used by your circuit. (12V)(1.5A)-(3.5V)(1.5A)= 12.75W. That means you will have to use a TO-3 package device with a heat sink. A more efficient choice (but more components) would be one of Maxim's switching regulators. It will have a few more components but the efficiency is approaching 80%.

Fast Eddie

[J Tiers]

Hmmmmm.....

LED......not on car or truck, but still a vehicle........I smell night vision, hunting, small vehicles, and IR illumination..........

If that isn't right, it is at least another good idea.....

[Thrud]

[he comments about voltage regulators are dead on - need it, get one. you seldom need more than a tantalum and a electrolytic cap on the output so that is just three components to deal with.

If the driven device is critical, crowbar circuits and over/under voltage circuits are sometimes utilized to protect the expensive electronics from surges and power supply failure (power supplies that implement these features are said to "die gracefully" when they explode as they cause no downline damage which can be critical and very expensive).

[lotsa luck]

Close, J Tiers... At least in some aspects. Now add water colling to the LED and see what you come up with. LOL

They can make it in IR also if someone might need that kind of IR output. After I get the thing to market I'll be able to post more on the maker etc...

[nheng]

Lotsa Luck, Asian vendors are very responsive and will quote things that we've also received no domestic response to. My primary concern, though, is that many of the Chinese suppliers are very small and their business charters and product lines can turn on a dime, or become swamped by someone else's large order ... leaving us in the dust. Good thing Wal-mart doesn't buy LEDs Den

[3 Phase Lightbulb]

Hey Lotsaluck,

If you don't mind, Can you remove/edit the PDF link you posted here that points to my website?

http://www.candlepowerforums.com/ubb...=&fpart=1&vc=1

I'm getting a lot of creepy crawlers originating from that URL and it just adds noise to my statistics.

-3Ph