Problem with LOC, AMC7135 and 2xaaa

I plan to use LOC in pen host that uses 2xAAA batteries.
I thought that AMC7135 is the best choice for this build so I put some AMC drivers to the test.

2XAAA give 3V and enough current.
Current though diode should be ~380mA but I can only measure 135-150mA.
No matter if I use rechargeable or normal batteries, both give same current.

Then I tried to use dummy load and test AMC 7135 and I discovered very strange behaviors of AMC chip.

With one silicon diode as dummy load current through diodes is 300mA.
Two silicon diodes give 360mA (should be fine for AMC)
With 3 diodes current through them is 180mA
4 diodes (that act like LOC diode) will give 150mA though them.
Any additional diode will just decrease current.

Then I tried to use Li-ion batteries (3.7V and 4.1V) and to see how they work with 4x1n4001...

With 3.7V battery current though dummy load is only 240mA.
But with 4.1V current is 360mA (Just fine for AMC).

As I know..AMC 7135 has volt-drop of only 0.1V and LOC diode will get 2.9V if I power them with 2xAAA.
But I can get only 135mA through diode...

I tried to test it with another 3 AMC 7135 drivers but each driver gives the same results.

Maybe I have different version of AMC? (L7135 0704) or it can not be powered with only 3V ?
Any ideas?

That LOC might be wanting a little more forward voltage than the 2 x AAA can make available. Does the laser run fine if you substitute a lithium for the two AAA? I have made two lasers LOC red that use the 7135 and a lithium battery. (one laser is CR123, other is 14500) I think I remember seeing a forward voltage of about 3.3V on a LOC red. Just went and checked, I measured 3.114V across an LOC at 350mA. Hope this helps.

Bill.

I think that 2.9v might not be enough. According to this graph of a Short Open Can, you need about 3.1v to run the diode at 350ma. Assuming that an LOC behaves similarly, You'll need at least 3.2v (3.1v diode + 0.12v dropout) to run at 350ma.

All of my LOC diodes have been tested. (Lm317)
I always get 2.9-3V forward voltage depending on the current.

As you can see, even 3.6V isn't enough.
4.1V is fine.
How can forward voltage of LOC be 4V?
That isn't just problem with LOC that I have, but even with 4x silicon diodes.

Can 4x 1N4001 give more than 3V forward voltage if current is 380mA?
I can measure 3.4V on these diodes when I give 4.1V to AMC.

I'm totally confused.

As shown in this graph, 1N4001 diodes will drop approximately 0.85v each at 350 ma. So four of them should drop 3.4v. This matches perfectly with your measurements.

Have you tried measuring the voltage across your LOC while running it at 350ma? I think it should be a bit higher than the 2.9-3.0v you claim.

At 380mA forward voltage of diode is 3.24V.
It's somehow higher.
These diodes are short-open-can that are from SF-AW210 sled.

So, I need about 3.3V.

Is there any other way to power up red diode with 2xAAA?

If you want to power a 3.3v diode with 2xAAA, you will probably need a boost driver.

Alternatively, you can use a Lithium-ion battery. When fully charged, they output 4.2v, which should be sufficient to run your diode + AMC7135.

It's easy to say
But I want cheap build.
I have pen host from damaged green laser, have AAA batteries, have scratched aixiz module (Had to lap module to get smaller diameter so I can use thermal tape to isolate it from case).
Has anyone tried to use driver from green lasers and to power up red diode?

EDIT:
Tested green laser driver and it's not optimized for red diodes at all

I dont think a green driver would work on a red diode. Green laser drivers are designed to power IR Diodes, which have a lower forward voltage than red diodes. A green laser driver probably would not supply enough voltage to your red diode.

Right now the only boost driver I know that can power a red @~350ma is the flexdrive. But at $23 it's not exactly cheap by my standards. I have been looking into cheaper options for boost drivers in this thread, but I doubt that any of these would fit in a pen host. The only board I have found that might work with your build is the DealExtreme SKU 7881. Its 10.5mm in diameter, and outputs around 320ma on a single AAA. But, I'm not sure if it can work off 2xAAA. I dont know how good regulation is either, or if the output current is adjustable.

Like I said, as a final option you can try using a Li-ion battery. The 10440 is similar in size to a AAA and will provide the necessary voltage to an AMC7135. Two in series will provide 8.4v and you can then use a simple buck driver to power it.

Nice find, but none of these drivers are not optimized for red diodes.
10440 batteries give enough voltage, but can not give 350mA to diode.

Can I use coil together with AMC?
Coil can generate higher voltage than 2xAAA, and AMC will regulate current.

Something like that..
http://laserpointerforums.com/f42/super-cheap-1-5v-diy-driver-45079.html

EDIT: I've just connected 2 AMC drivers in parallel connection and current has increased from 135mA to 160mA.
What if I connect more AMC drivers?
btw..voltage drop across diode is 2.5V

Diode can burn, but not enough to satisfy me.

You're right, these drivers are not designed for driving red diodes. However, they are used for driving HB Leds, which are similar. If the output isn't stable enough, I think you could use one of your AMC7135 chips on the output to regulate current. Though I have never tried using any of these boards myself, so I cannot guarantee that any of this will work.

As for the 10440 Li-ions, I dont think you should have any problem getting 350ma out of them. Most 10440 cells I've looked at are rated for 1.5C maximum discharge. Assuming you buy a 350mAh battery (such as this one), that will give you a maximum discharge current of 525ma.

You can try building a switching regulator driver with a coil, but these drivers can get a little bit complicated. I dont have much experience in this area, and cant give you much advice. But keep in mind that the joule thief circuit you linked to is not current regulated. Here are some threads that document how to build a boost driver if you want to try it yourself.

http://laserpointerforums.com/f42/2-aaa-ni-mh-1-li-po-adjustable-laser-driver-26912.html
http://laserpointerforums.com/f42/2xaa-blue-ray-driver-fits-aixis-26662.html

You can find more threads on this subject by searching for "boost driver" or something similar.

I have BR laser (110mA) powered by 6x10440 ... 2 x (3x10440) in parallel because 3x10440 batteries with Lm317 can not give stable current.
Current starts from 110mA and after few seconds drops to about 60mA.
But when I added one more pack of 3 batteries in parallel connection current went to normal.
I used these batteries.... DealExtreme: $4.23 Ultra Fire 10440 3.6V 500mAh 2Pack
This is why I think that 10440 batteries can not give 300mA.
But this may be just bad experience with bad batteries.

If 10440 batteries can give 350mA it would be great.
I already have SMD Lm317 and PCB that fits aixiz module. (Thanks to Eudaimonium)
Do you have experience with these new protected 10440 batteries from DX?

I agree, boost drivers can get complicated and mostly can not fit in pen host.

I have never actually tried using 10440 batteries (I dont have enough money to actually try anything out :cryyy. However, I have read a number of threads on CandlePowerForums and DealExtreme Forums where people are using them to power flashlights at well over 350ma. I'm not sure why your PHR needed so many of these batteries to work. Fully charged they should have provided 3 x 4.2v = 12.6v, which should have been more than adequate to drive a lm317 + PHR. Did you ever verify that the voltage of 3 in-series 10440s was near 12v?

On a side note, I did not know SMD LM317s were available. Are you talking about the LM1117? Does Eudaimonium sell both the SMD LM317s and the PCB?

I don't want to buy these batteries again if they can not give 350mA.
If anyone has these batteries please let me know if they can give 350mA current.
And of course... 3x10440 give almost 13V when fully charged.

LM317 is available in SOT-223 packing.
I don't know if Eudaimonium has more SMD lm317 and PCBs...he sent me driver as a gift.
(Thanks Eudaimonium)

spectral532 said:

...

On a side note, I did not know SMD LM317s were available. Are you talking about the LM1117? Does Eudaimonium sell both the SMD LM317s and the PCB?

Click to expand...

Well I don't sell anything actually, I just trade with ReNNo here and there. I got those LM317 in SMD package a long time ago, made a DDL that fit inside a aixiz module, with a potenciometer and a cap stuffed in.
So I had these surplus since I already have LM1117 of same package, so I sent it to ReNNo, figured he will make better use of it. Apparently he did.
Speaking of matter, I also sent him that AMC drivers we are all discussing.
Problem is that I always used it in my red laser since I got them. I never actually bothered to measure the current ... I figured they do the job, because my reddies to appear powerfull enough, one with 2X AA batteries is kicking out a lot of red... managed to do that optical trapping thing and a lot of other wonders.

ReNNo said:

LM317 is available in SOT-223 packing.
I don't know if Eudaimonium has more SMD lm317 and PCBs...he sent me driver as a gift.
(Thanks Eudaimonium)

Click to expand...

Nope, that was the last one I had. I had one more but I managed to somehow destroy it while desoldering from old PCB. Gripped too tight with my pliers. Sorry, that one was also meant to be in a package for you, but hell, tough luck

EDIT : Oh yeah, if anyone thinks that typing my nickname is timeconsuming pain in the butt process, just punch in JZ, or simply Z (as of my real name's initials, Jakupec Zdravko), a'ight?

Eudaimonium said:

EDIT : Oh yeah, if anyone thinks that typing my nickname is timeconsuming pain in the butt process, just punch in JZ, or simply Z (as of my real name's initials, Jakupec Zdravko), a'ight?

Click to expand...

Why ? i don't see any problem typing Jakupec Zdrva ..... Zdarv ..... Zadrkv .... Zdwrngbly .... ok, nevermind, Eudaimonium is more easy :crackup:

(Just Kidding, ofcourse )



BTW, you can find LM1117 in SMD packages, both the TO252 and the SOT223 ones on ebay, here and there (i usually buy them there too, cause here in Italy the distribution is simply a damn crap mess )