1A LM317 driver with current selection switch

[IWIRE]

Mines not near as pretty as yours. I was wanting to see how small I could keep it and used the 338 itself to mount components to. Lmao ! I really did. I thermal glued the chip to a piece of aluminum, checked to make sure it stayed electrically isolated from the aluminum.

Then I folded the leads back over the chip, soldered an smd resistor across the adj and out, soldered an smd trimpot right next to it, tucked a couple capacitors along the side, one on the input and one on the output.

I couldn't believe it works. I have to admit it's pretty scary looking. Looks like a short waiting to happen :crackup:
I'll refine my next one a little better. I should take a pic of it. It's worth a laugh

 

[alessnilsen]

Re: Will LM317 work on 7.5V 1A for blue LD? Driver assembled.

SMD? Really? That's crazy! I already done some circuits using this kind of build! The feeling of turn this kind of stuff on hoping for the best is unforgettable! :beer:

I done a lot of LM555 experiments! Think about resistors, large 470uF caps, trimpots, a transistor, a 7805 and a large relay, all soldered directly into the 555 pins! Was the most scary thing I assembled! And worked! :crackup:

I'll refine my next one a little better. I should take a pic of it. It's worth a laugh

Yes! Now I'm curious!

Just look the photos on this article from Wikipedia! That's realy scary!

 

[The Lightning Stalker]

Re: Will LM317 work on 7.5V 1A for blue LD? Driver assembled.

There is some point to point construction in the Laser Router thread over in the general forum.

 

[IWIRE]

There is some point to point construction in the Laser Router thread over in the general forum.

Thanks . I'll check that out. I'll take any help I can get. :beer:

 

[alessnilsen]

Re: Will LM317 work on 7.5V 1A for blue LD? Driver assembled.

Can someone say if shorting a resistor to change the current of the driver can be dangerous for the laser diode?

I already done this with red diodes, but with a U$45,00 laser diode is different.

How can I protect the diode from any spikes that it can cause?

 

[IWIRE]

Can someone say if shorting a resistor to change the current of the driver can be dangerous for the laser diode?

I already done this with red diodes, but with a U$45,00 laser diode is different.

How can I protect the diode from any spikes that it can cause?

I'm not sure you could say for sure unless you hooked it to a scope and tried it ? It seems like electricity is an exact science to a point then it morphs to electrical theory. I will never say something can't happen because it will prove me wrong.

 

[alessnilsen]

Re: Will LM317 work on 7.5V 1A for blue LD? Driver assembled.

I don't have any oscilloscope to use, I was thinking in use my old computer to do this.

 

[IWIRE]

I don't have one either. If I start playing around with drives much I can see where having one would be a necessity. Makes sense to me, get a few grand tied up in trying to make a $25 drive :crackup: I've been known to do crazier things though

 

[alessnilsen]

Re: Will LM317 work on 7.5V 1A for blue LD? Driver assembled.

I done it using my notebook and the result was awesome! :beer:

All measurements was taken with a 5.5V test load between the 1R resistor.

Firstly the output of my driver (those interferences are so tiny!):

Now switching the current DOWN!

Now switching the current UP (shorting the 2X1,5R resistors)!

And now, a close up of the switch spikes!

I think is OK, because the spikes ever respect the current limit.

Adding a 330uF 10V capacitor in the output of the driver makes the spikes more smooth:

When turning the current down, all is perfect!

I think this driver is enough stable for my U$45,00 diode! :yh:

 

[IWIRE]

I done it using my notebook and the result was awesome! :beer:

That's pretty cool. That would probably work well enough for my needs at the present time. I'm not sure I would want to use my good laptop, but I have an old one not doing anything. :beer:

 

[alessnilsen]

Great! That's how I done:

Just adjust your driver and then, set the potentiometer to output only 0,1V.
Here is the software I used: Link

That would probably work well enough for my needs at the present time

What measurements you wanna do?

If you need help let me know! :beer:

 

[IWIRE]

Great! That's how I done:

Just adjust your driver and then, set the potentiometer to output only 0,1V.
Here is the software I used: Link

What measurements you wanna do?

If you need help let me know! :beer:

Thanks for the offer of help. Very seldom do I bother people with questions or ask for help. I make lots of mistakes but I remember the lessons learned

There are some members here that are kind enough to listen to me ramble in PM`s as I work my way toward solutions.

I'm pretty good at wiring and electricity. I just suck at electronics. But I'm learning

All I'm really wanting to measure is stability and overshoot.
:beer:

 

[alessnilsen]

I'm pretty good at wiring and electricity. I just suck at electronics. But I'm learning

I'm the inverse case, I had a course of electrician, that's not my way! But in electronics I think I'm good enough.

All I'm really wanting to measure is stability and overshoot.

Then I think that's enough for your needs, as I do some modifications in my DDL drivers, it's cool to know if it will work stable and what is the consequences.

The only thing I don't done is to make a driver with linear current control, using a common potentiometer (lot a large 4W one), my electronic simulator doesn't have an LM317 on it's library.

 

[IWIRE]

That's what is so cool about this place, everyone has strengths and weaknesses, we get to share and learn from each others strengths. The first laser I built I went through I think two diodes and four drives :crackup: I haven't blown a diode or drive in months, so hanging around this place must help :beer:

Edit:
I can see now why you used a fan. This thing gets hot really fast at 4.4a. First my resistor started smoking :crackup: I installed a better resistor. Then I had to put the 338 on a bigger finned heatsink. Now I need a fan. I won't have that much room . Oh, well. It was fun to play with.

 

[alessnilsen]

That's true! I love opening random topics to see what persons are asking/showing! My last mistake was kill a LD with it's own bean reflected back into it.

I know. My 317 at 19V generates a lot of heat, if I leave the fan off and start to use the driver, it will go over 70¡ãC! With the little fan on (12V running at 10V) it will be stable at 30¡ãC!

For 4.4A you will need a fan with sure. If not, a really big heatsink. I recommend a computer CPU heatsink fan.

:tinfoil:

 

[IWIRE]

I took mine off the little aluminum plate I had it mounted on and mounted it on an actual heat sink. I shot it with an IR thermometer and it was staying below what the max temp is on the data sheet. It sure seemed really hot though. I haven't gave up yet
If I dial it down to 2.2a it runs a lot cooler, like what I was expecting. I might try paralleling two of them, at least it would spread the heat out over a larger area. Not sure if they can be paralleled or not, seems like I remember they can be.

If I decide to use these they will be mounted on a 1/4" aluminum plate inside a plenum with a couple CPU fans for airflow, the little 1" square fans, that's all I have room for.
:beer: