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Micro-Drive laser driver by rkcstr

Hey, no worries... I can't even remember how many diodes I've blown. I have a bag of em somewhere. But, glad to see you got one working.

And, if you accidentally short the diode leads when connecting the driver and you power it up, it should be fine. The diode basically won't see any power and the driver will just put the current through the short (won't hurt it). Obviously the diode won't produce any light, but if you remove the short, it should be OK. Just heat up the pins and remove the diode from the driver, remove the excess solder from the diode/driver and then re-solder them together again. Of course, overheating the diode could be a cause of failure too.
 





rkcstr said:
Hey, no worries... I can't even remember how many diodes I've blown.  I have a bag of em somewhere.  But, glad to see you got one working.

And, if you accidentally short the diode leads when connecting the driver and you power it up, it should be fine.  The diode basically won't see any power and the driver will just put the current through the short (won't hurt it).  Obviously the diode won't produce any light, but if you remove the short, it should be OK.  Just heat up the pins and remove the diode from the driver, remove the excess solder from the diode/driver and then re-solder them together again.  Of course, overheating the diode could be a cause of failure too.
Click to expand...

Yeah, after I failed to remove the excess solder..I sort of stopped caring how hot the thing got... although I am glad you told me this, cause that is good to know the diode probably wasn't dead from the solder bridge I made and connecting the driver, this will be good to know for later :)

But at any rate, the diode is being run at 51mA and is doing 3.4mW's. I am surprised at how bright it is for such a low power rating, I guess few nanometers in one direction make a huge difference. But I was hoping it would do 7mW since that's what most of them were doing, maybe I'll ramp the current up a bit, cause twice the mW output should be twice as bright, which would be very nice looking.

I got 10 more of these coming to me, so I can still have some more fun practicing. And to be sort of on topic here, your drivers can sure take a beating. I have abused the hell out of the one shown in the pic, and it still works like a charm. ;D
 
I have a question regarding the voltage on these things. I read that the rkcstr can handle 12 volts...is this only with a Blu-Ray? Or could I effectively put 12v in with a rkcstr connected to a red diode?

Also, how much over 12 can it handle? Like 3 freshly charged lithiums would be somewhere between 12.3v and 12.6v, is this Ok?
 
leukoplast said:
I have a question regarding the voltage on these things.  I read that the rkcstr can handle 12 volts...is this only with a Blu-Ray?  Or could I effectively put 12v in with a rkcstr connected to a red diode?

Also, how much over 12 can it handle?  Like 3 freshly charged lithiums would be somewhere between 12.3v and 12.6v, is this Ok?
Click to expand...

I've done it, but I don't know if you're supposed to. I've used 3 lithiums powering a red on a DDL driver, and I've and many others have used 3 freshly charged lithiums on a blu-ray, but I don't know if that's good or not for the driver, ask rkcstr.

BTW rkcstr, when are you gonna start selling drivers again? I'd want 2 fixed (I've never bought from you before, only two from other sellers)
 
The recommended max input to the driver is 12V due to the input protection component's voltage rating.  Others have successfully used three 3.6V batteries, with their peak over 12V, without a problem.

For a red diode, I would suggest less than 9V max just because of heat.  The greater the input/output voltage difference, the more heat is generated.  I've tested the heat to not be an issue with a ~3-4V difference at the max current (430mA), but when you're talking up to 9V+ difference, that will probably significantly increase the possibility of overheating the driver, which will cause it to shut off or fluctuate in output, possibly damage if allowed to operate under those conditions for long.  Of course, that will also depend on your driving current and not just the input/output voltages.

I will start selling again, but I'm studying for an exam I have on Tuesday right now.  I'll probably start up again the next weekend.
 
Good to hear, I am definitely going to order a few more adjustable ones. :)

And one other quick question (I know, I have a lot of these), back when my 635nm diode was working, I was using a single lithium cell (which was at something like 4 volts at the time) to run it. But I realized after the diodes mysterious death that I was giving the driver/diode less voltage than it needed. (which would have been 5.25v correct? 3v for red diode and 2.25v for driver) I am just wondering, is this a bad thing to do? Could it have damaged the diode or driver?
 
No, undervolting it won't damage it or the diode. However, it could cause you a problem if you set the current on a battery with say 3.6V and then use a battery that is freshly charged at 4.2V, as it will put out more current than when you set it, which could possibly overdrive your diode.

I don't know what voltage those 635nm diodes run, but you will need >2.25V over their operating voltage. If that is 3V, then 5.25V would be the minimum for regulated current. You should probably go with at least 6V worth of batteries so you get a decent life before the current drops off.
 
rkcstr said:
No, undervolting it won't damage it or the diode.  However, it could cause you a problem if you set the current on a battery with say 3.6V and then use a battery that is freshly charged at 4.2V, as it will put out more current than when you set it, which could possibly overdrive your diode.

I don't know what voltage those 635nm diodes run, but you will need >2.25V over their operating voltage.  If that is 3V, then 5.25V would be the minimum for regulated current.  You should probably go with at least 6V worth of batteries so you get a decent life before the current drops off.
Click to expand...


That might have been the problem. Cause I set the current with the 3.7V lithium, and yesterday I had hooked up 2 lithium's...which is when i noticed it wasn't as bright as it had been. So from now on, I should probably set the current with the highest possible voltage that I plan on inputting?
 
As long as it is above the voltage threshold needed for regulation, the current will be constant.  When it is below, the current will continue to drop as the voltage does.  So, just ensure you have enough voltage to meet the needs of the driver when setting current.  I typically use a 9VDC wall adapter (not a 9V battery) to set currents since that should be more than enough for most diodes (unless you have one going upwards of 6.5 to 7V of Vf).
 
rkcstr said:
I typically use a 9V AC adapter (not a 9V battery) to set currents since that should be more than enough for most diodes (unless you have one going upwards of 6.5 to 7V of Vf).
Click to expand...

I hope you are using a [highlight]9VDC[/highlight] adapter for power.

Good job on your driver design.

LarryDFW
 
haha, yeah... I assume most people would understand it should be DC, but I guess I should make that clear (I did change it to better reflect what I meant).  I wouldn't suggest trying it, but 9VAC probably wouldn't kill the driver.  It would probably just make it act "weird" since the input MOSFET and cap would act as a sort of 1/2 wave smoothing rectifier, just giving a 60hz fluctuating voltage.  I don't know how stable the operation of the circuit would be, though, so I wouldn't suggest trying it unless you want to risk your driver and anything connected it it's output.
 
I'm taking orders again. Limited amounts of assembled items available (same as before).
 
Sweet! I broke my other adjustable driver, and I just flat out need some more. A order of 4 adjustable will be ok right?
 
Yep, just placed an order for four fixed (2x 125mA, 2x 422mA). I've never used you're drivers before (only two I bought already attached from outside an aixiz module w/ the diode already wired up), so hopefully everything works out just fine. btw, I had a question about using your driver w/ 3x 10440 batteries - is it fine to use that, or can it be bad?
 
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