FREE DIY open source BOOST driver!!! Tested & working!!

Hrm.. That is neet! an easy solution.. I thaught you said the round boards had bad scope readings???

Kizdawg said:

Hrm.. That is neet! an easy solution.. I thaught you said the round boards had bad scope readings???

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I have to double check that with other caps but it was on my desk so I gave it a shot and I can't remember how bad were they now, too much stuff on my mind, I will check it again tomorrow . )))))))))

but it will work on the rectangular too, and on the hexagon one

How does the Zener give you OVP? I am trying to understand the Zener better. It flows current forward with no problem, but it only flows current in the other direction once it reaches the "avalanche" voltage. Correct?

So what is it doing that gives OVP?

Thanks!

It tells the IC to stop boosting the voltage when no load is attached, without it the IC will try to boost the voltage til it fries itself

So if the voltage is less than 6.2v, it goes through the laser diode and the Zener doesn't allow any current to pass through it. But if the laser diode fries and the driver tries to boost to infinity, the Zener diode collapses at 6.2v and becomes the pathway that the driver feeds the current.

With some of the new diodes, maybe an 6.8v Zener might be better?

Btw, that is pretty ingenious! It cranks my tractor!

Without the 100 ohm resistor you can leave it open load very long! It may only stand it for a few seconds, depending on the set current. The 100ohm resistor sets the current to about 2ma when The current is going through the zener. Without it the zener has to withstand whatever your set current is! A 6.2v Zener with a 1.2A driver is 7.4W of heat in the zener!

Fair enough, but you can get a high wattage Zener, right?

I have another question, can you still put a cap across the LD+ and LD- with a Zener there too? Will that create a problem?

No Zener that will fit on that board can handle 7.4W. That's more heat than there is on the laser diode and it still gets hot with a huge heatsink!

You should leave that cap off all the boards. Remember it caused weird oscillations

Here's a relatively small 3W.

How far apart are the pads? These are 2.25mm apart.

1SMB5921BT3G - ON SEMICONDUCTOR - ZENER DIODE, 3W, 6.8V, SMB | Newark

If you were running a ~500mA 12x or LPC-826 that would be 3.4W.

foulmist said:

btw ben, with only the zener in place, the driver doesn't output any current even without the resistor. I know that's why the resistor is used to lower the current across the zener. BUT it just doesn't put out any current without it. It just sits the voltage to the zener's breakdown voltage and no current.

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Wow, I have a lot to learn from you guys.

Without the 100 ohm resisitor wouldn't the resistance actually still be there, but very very small - like .0000001 ohms and wouldn't it still flow current?

I agree with Tsteel I have alot to learn from you guy's... I never seem to have the time to do it all so it's a slow process.. + the small business is killing me... 16 employees and each and every one of them have a problem allmost every day... I need to Expand and hire some managers and more part time people that could be on call!!!

Then maybe I would have the time needed to learn all this. My bonus going for me is I have alot of software experience and can usually pick up on software very quickly. Still trying to wrap my head arround Eagle.. Need more time lol Well.. Shower, work... *Star* cook went to a 'Pool Party' last night and called in sick... It was supposed to be my day off... and I had planned on going away to the lake next week but I dont see that happening any more...

HAHA!!! I got him!!! I had the waitress call back and tell him he had to go get a Doctors note if he wanted to work again.. LMFAOROTF>.. Giggling! he showed up 20 mins later.. apparently fine.. He would have been waiting 6 hrs to get a note... Guess I screwed up his TTF He should have just said he was going to be l8...

No Ben is right!!!!!! Without the resistor the driver burns out again I just tried it ... I don't know why it didn't burn yesterday but now it sure burnt out pretty good and smoky

DON'T DO IT!!!!! I was wrong!!!

Valuable lesson learned today while setting up my recently purchased 1.256A Benboost from CajunLasers.
First of all at that current it needs good heatsinking as the current starts dropping a couple of seconds in the run.

Second: while I'm still waiting from my heat conductive adhesive to arrive from DX, I tried "fixing" the driver to a dedicated heatsink using silicone+ceramic heatsinking compound from radioshack (non conductive, non capacitive) and use the glue to actually keep it in place. Well, it shorted somewhere and Poof went the Shottky diode...

For the future I'll be attaching any divers using two layers of adhesive, one will be applied to heatsink and let dry, followed by a second layer on top of first, to which the driver will be bound. I hope this way the driver will be prevented from coming in contact with any heatsink surface...

Now I wonder If that diode was the only thing that burned.... Good thing I have a second driver.

I have lots of parts for these if you need...

Check out the OP guys!

I added a donate button for those who want to support the continued development of this project! I also made some edits a couple days ago too.

I have parts and boards to test benboost mini. I didn't have time to make one last night, I was working on a different driver. I'll reflow, test, and scope it today or tomorrow!

This is great! I have made a little donation just now. Will make more come next paycheck!
Ben, RHD are you working on any more drivers Buck, Buck/Boost? Just curious