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-   -   LM1117T-ADJ curcuit help!!!! (http://laserpointerforums.com/f51/lm1117t-adj-curcuit-help-40852.html)

b52productions 05-31-2009 07:11 PM

LM1117T-ADJ curcuit help!!!!
 
Looking to build my own drivers for open can red and phr-803t's

Options to power driver with:

(3) Ultra Fire 10440 3.6V in
(3) 1.2v AAA

My driver choice is the LM1117mpx-adj so i can use it for both diodes.

Question 1- would it be better to use the 3.6v parrallel or in series at
10.8v.
I know the voltage varies as fully charged and when its discharging so keeping the supply voltage above the requirments of the diode +1.2v "required by the driver" as long as possible would be best since this is not a boost curcuit. As long as you dont exceed component capabilities.

Im not sure if 10.8v input produces more heat or not as compared to the 3.6v input that would quickly drop below voltage requirements.

here is a quick post on the lm117:


The LM1117 is a series of low dropout voltage regulators
with a dropout of 1.2V at 800mA of load current. It has the
same pin-out as National Semiconductor’s industry standard
LM317.
The LM1117 is available in an adjustable version, which can
set the output voltage from 1.25V to 13.8V with only two
external resistors. In addition, it is also available in five fixed
voltages, 1.8V, 2.5V, 2.85V, 3.3V, and 5V.
The LM1117 offers current limiting and thermal shutdown. Its
circuit includes a zener trimmed bandgap reference to assure
output voltage accuracy to within
±1%.

worst case senario i figured batteries in series 10.8v for phr-803t
and parallel 3.6v for lpc-815.

if you can suggest another battery option for red can diode please do.

Question 2: How do i limit current.
since i use this as a voltage regulator could i use a resistor to limit current to the diode. would that be a larger value before the regulator or smaller value after ?

this is what i got:
http://i437.photobucket.com/albums/q...oltscopy-1.jpg
Any help is appreciated.:thanks:

BuildAbluraylaser 05-31-2009 07:35 PM

First, there's a driver perfect for that that has been created, search "DDL driver" also, fully charged 10440 is 4.25v, I only use two for my lasers. Use the search button, and go take a look at the compiled list of tutorial, I thinks you can find it there. You will need to get a dummy load, super easy to build, to set the driver.
Connect the batteries in parallel, no problem, the heat isn't significant.

USE THE SEARCH BUTTON

chipdouglas 05-31-2009 08:17 PM

also i'm too lazy right now to search but go to rog8811 member profile and in his signature he has all the links you need to make it. i thin it is called the LM317/ddl driver. good luck. and yeah i wouldn't use 3- 3.6 v batts use 2. if your host needs 3 then you could use washers to fill the void or get a rkcstr driver.

edit* here is the link
http://www.rog8811.com/laserdriver.htm

b52productions 06-01-2009 04:53 AM

thanks, i have looked over the turorial. i plan to build anyways since i already orderd the parts. Im using a premade pcb removing the regulator and moding it with new parts :) will keep posted on progress.

before mods- uses reverse polarity driver. not good since i cant isolate the diode can from the host nor do i want to.
http://i437.photobucket.com/albums/q...emesku1886.jpg

If all else fails i will try my attempt at the ltc3454 i think flexdrive uses it

ps. rockstar is out of stock

Darkarmyofone 06-01-2009 01:32 PM

b52, where can i get an all copper heatsink for the flashlight in your signature? PM sent just in case, and im assuming their fit for meridiths?

Kenom 06-01-2009 02:08 PM

the original driver your looking at is called the groove driver and works perfectly fine.

pseudolobster 06-02-2009 02:17 AM

It seems these regulators (and really, any LDO version of the 317) are a bit more finicky than the LM317... Apparently they oscillate badly with the wrong choice of caps. I've been told you should use high frequency low ESR tantalum caps, though I don't really know why.

Here's the schematic I was given for making a driver from these regulators:
http://www.laserpointerforums.com/fo...ents/l1117.JPG
Thanks to Phenol for the schematic

As you can see it's basically the same as the DDL driver, but with more caps. The main difference between this (a current regulator) and the schematic from the datasheet you posted above (a voltage regulator) is that the pot is tied to ground.

I'm not really well versed in electronics, so I can't give you much more advice, though this should get you started.

b52productions 06-02-2009 05:08 AM

thanks for the help. i will try and keep posted but im not sure how to track all my posts in the forum. i forget where i made posts at LOL.

Kenom 06-02-2009 05:16 AM

you can click on thread tools at the top of the page and subscribe to the thread. Even recieve email updates as someone posts in the thread.


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