voltage regulator help - ot

[mister_e]

mmmpfff can't agree 100% with you Alain. Desolé

Switching regulator are great... but linear too. No more improvement over the previous ... oh well maybe a bit less of heat... but much expensive... at the end, you never ever save a cent.

Just rethink of your reply.. If you regulate the current... it's still a 3 LED driving plah plah. What will be the result when all 3LEDs have to be Full on to produce a WHITE color? Nothing else than a dimmed white

[Acetronics2]

Hi, Steve

I think we could know better what Doc' wants to do ...

a "simplissime" current regulator can also be achieved with a Red Led as volt ref, two resistors ( one for LED and one for emitter current ) and a transistor.

That makes 3 cases ... if TO 220 ... makes min. 3 watts to be dissipated.

Alain

[docwisdom]

Thanks for the replies.
When I arrive home today I will post a schematic. For now, here is a link to the LEDs I am driving http://www.laminaceramics.com/products/bl4000.aspx. For now I am running 1 RGB, I would like to run up to 8 in parallel, therefore the necessity for powerful regulators and powerful mosfets.
I tried using specialized LED drivers, but they all maxed out at 1amp. Cost me $60 too, I may sell them or return them.

I am a filmmaker by trade and that is the ultimate purpose for these LED's. A low power solution for car kits and mobile rigs.

P.S. My source voltage, ~12-14v will not be constant, I know that. A switching regulator that doesnt vary ouput based on input would be nice. The LT1074 looks interesting, also the LM2676. What do you think?

[docwisdom]

Here is the full schematic, it includes the LED drivers instead of the mosfets.

[Acetronics2]

Hi, Doc


Looking back to your first post ... make me think using LM350 ( T or K ) or LM 338K's ( 5A )instead of the 317's would be a very good solution ... as it exists some insulating silicone pads ( or Mica sheets ...) and insulating spacers to avoid connecting reg.case to your aluminium casing !!!

The " best " solution surely is here !!!

See here i.e. : http://www.selectronic.fr/soussousfa...0&ssfam_ref=30

or here : http://www.selectronic.fr/soussousfa...0&ssfam_ref=20


Alain

[BigWumpus]

It's not easy for us to understand your problem.

You are mixing up linear regulators and switching regulators... we don't know what voltage and current you need...

I think you want to build a luminated heater. You want to burn away a lot of the electric power in your regulators in order to give a little piece of power to your LEDs.

Think about switching regulators !

[docwisdom]

The RGB led's need 4.5, 6.7, 7.6 volts respectivly and draw 350mA per color. for a total of 1.05 amps per LED unit.

I would like to run 7 or 8 of these in parallel, giving me the necessity for 8-9 amps of total current. So 3A per color.

so to break it down, I need [email protected], [email protected], and [email protected]. Each controlled via hpwm from the pic.


hope this clears it up

thanks
-brian