Drivers for 445

Jay,

The Shark Buck can handle a large range of forward voltage.

Here is what Wayne the designer mentioned about voltage output:

"As long as Vin is higher than Vout you can use multiple LEDs in series on the output as long as the total Vf is less than the input voltage."

So our laser diodes provide no voltage problem.

As for power throughput, this driver has been tested to over 11 watts at up to 25V input!

The board also uses 2oz copper trace instead of 1oz so it will pass excess heat into the spreader quite nicely.

Found it...
Shark Buck - CandlePowerForums

So what are you planning on for your supply voltage? 2 X 18650's?

jayrob said:

So what are you planning on for your supply voltage? 2 X 18650's?

Click to expand...

No, I am modifying a single 18650 host to take two 18350s. I turn the switch button aluminum retaining ring down a few MM, as well as file on the switch itself to shorten the body. It is a very close fit. Of course, if you aren't concerned about every last bit of capacity, two RCR123s could be used instead without modification.

Howabout this Sandwich Shoppe

it is cheaper. Only 1A out max fine for me though... What do you think jay?

Looks interesting too...

No pot, so it's just going to depend on the battery used vs the diode efficiency I guess...

Would be interesting to test. So far I'm still sold on the Micro BoostDrive...

jander6442 said:

Howabout this Sandwich Shoppe

it is cheaper. Only 1A out max fine for me though... What do you think jay?

Click to expand...

Why do you want to run that supply if you are running a current that a Microboost can easily handle?

I am using a buck converter because I'm going to be running over 1.5 amps and don't want to deal with adjustment of two drivers.

If you want 1A, use a DrLava driver.

Just something diffrent I guess. I did say it was cheaper though

jander6442 said:

Just something diffrent I guess. I did say it was cheaper though

Click to expand...

Touché :yh:

I was wondering, earlier DrLava had mentioned the amount of capacitors on the board effecting filtering capability. Is this current filtering or voltage?

Is there any easy way to test the filtering ability of the board? I was looking at the Shark Buck, and it looks to have a good amount of capacitors on it like the Microboost I am looking at.

Exerd said:

:

I was wondering, earlier DrLava had mentioned the amount of capacitors on the board effecting filtering capability. Is this current filtering or voltage?

Is there any easy way to test the filtering ability of the board? I was looking at the Shark Buck, and it looks to have a good amount of capacitors on it like the Microboost I am looking at.

Click to expand...

New member here, so I will take a crack at it, easy on me if I am wrong
"Is this current filtering or voltage?"
You can't really do one without the other, so I would say both.
"Is there any easy way to test the filtering ability of the board?"
The simplest way to do that would be on an o-scope, you are looking for ripple.
It might be a good idea to email Wayne at the Sandwich Shoppe and see if he has any pics or screen caps of the output waveform from the board. As far as I know, it should be quite stable, but I am inexperienced with laser diode requirements. Just at a guess, a .1 mic and a 10 or even 100 mic cap paralleled to the output would almost certainly clean up any transient voltage spikes. Another option might be a TVS (transient voltage supressor) but I wouldn't know how to choose the proper one.
I hope someone does scope the output, it would be educational.

I defer to other more experienced members but this might answer some questions, or at least start a dialog.

VegasF6

vegasf6 said:

New member here, so I will take a crack at it, easy on me if I am wrong
"Is this current filtering or voltage?"
You can't really do one without the other, so I would say both.
"Is there any easy way to test the filtering ability of the board?"
The simplest way to do that would be on an o-scope, you are looking for ripple.
It might be a good idea to email Wayne at the Sandwich Shoppe and see if he has any pics or screen caps of the output waveform from the board. As far as I know, it should be quite stable, but I am inexperienced with laser diode requirements. Just at a guess, a .1 mic and a 10 or even 100 mic cap paralleled to the output would almost certainly clean up any transient voltage spikes. Another option might be a TVS (transient voltage supressor) but I wouldn't know how to choose the proper one.
I hope someone does scope the output, it would be educational.

I defer to other more experienced members but this might answer some questions, or at least start a dialog.

VegasF6

Click to expand...

Current is what we are concerned with, too much current and the LD burns up, too little and the LD will not lase and will output like an LED.

Right, you are. LD and LED Drivers do consume some power to do their job properly. typically 1.5v - 2v.
The goal of the DC-DC convertor is to limit output current.

Seoul_lasers said:

Current is what we are concerned with

Click to expand...

I guess that's where I get a little confused with the mention of capacitors. I know that a drivers main purpose is to regulate current, but I didn't think it relied on the amount of capacitors to perform that duty. See where I'm going?

Basically, I'm trying to tackle the idea of how it would be determined that a laser diode driver is "better" than an LED driver at driving a high power diode. I mean, an LED is a diode, and the 445nm diode is as powerful as many of the LEDs out there. It seems to me that drivers should interchange quite readily at this power level, whether for LED or laser diode.

I merely went along with the idea that a laser driver should be used when possible, but now I'm starting to question whether or not it would even make a difference with these very tough diodes. People are direct driving them, for what it's worth.

No regulator is perfect though. There is always a certain amount of ripple, spikes and noise. Light emitting diodes, especially the power diodes like Cree XRE, SSC, SST-50 etc are somewhat tolerant of these spikes (though I have managed to blow them before by not discharging caps before hookup). In the case of a switch mode or PWM circuit 2 caps are usually put across the output to smooth out the noise and the ripple. The smaller cap has a faster response time and will filter out signal noise and the larger to catch the bigger spikes. However it wouldn't be correct to say that it relies on the capacitors to regulate current.

My knowledge is a little fuzzy here so again, I may not be explaining it quite right.

What surprises me is the need for these caps when using battery power and a linear driver, as opposed to another type. A linear buck circuit should have a very smooth output even without these caps, shouldn't it? I don't have a scope to look at that though.

As to how much difference there is between an led driver and a high powered ld driver, I hope to learn that too. One thing I have seen stressed over and over again is how static sensitive an ld is. In a case like that we would be talking about somewhat high voltage but very low current damaging the diode.

In an article I was reading recently about ld driver design (can be read here) it states "Because these
lasers are exceptionally sensitive to overdrive, power to
the laser must be carefully controlled lest it be damaged.
Over-currents as brief as 2 microseconds can cause
damage." and later is states "The output capacitor C2 has been specified for low
ESR, and should not be substituted (damage to the laser
diode may result)." so apparently they are pretty delicate.

Anyone know if I use a 3.7V 900ma battery I can power my 445 A130 diode?

The current that I will set is 650ma.

Tks

That will work just fine with either a V5 FlexDrive or a Micro BoostDrive...

I tested the V5 FlexDrive last night at that exact setting. See here:
http://laserpointerforums.com/f51/questions-about-micro-boost-drive-52284-2.html#post729888

If one wanted to use an LED driver... could capacitor(s) just be added to the Laser Diode leads?
How much capacitance would be needed?

I had a quick question about the quality of different batteries for use with 445nm lasers. I have an LG 18650 battery, and if I leave the laser on for long enough, the driver begins to pulse. I'm using a microboost set to 1 amp of current. Funny thing is the battery reads 3.95V on a DMM so it isn't drained.

Is the pulsing due to the fact that the battery is having trouble supplying the necessary current?

If so, should I invest in a more reputable brand like the AW 18650s?