No New Projects?

[swamidog]

i don't know who said it. i'm not pinning it on bill.

i'm all about new and hopefully better products. we all benefit from competition. there's just no reason to insult the previous engineers and products that we're trying to improve upon.

Swami have you scoped the output of all the other drivers? I haven't them all but can say some have had some noise in them. I think this is going to be extremely clean.
Also those weren't Bills words they were someone on the dev sides.

[polishedball]

i don't know who said it. i'm not pinning it on bill.

i'm all about new and hopefully better products. we all benefit from competition. there's just no reason to insult the previous engineers and products that we're trying to improve upon.

Got it. 1515161515

[buffo]

Buffo,
Can you give out any of the proposed specs. Even if they are preliminary, it would be useful to anticipate how they might be used.

A lot of this will depend on the outcome of some final testing that will be done this week and next week. The initial goal was to produce a driver that could deliver a maximum of 10 amps at up to 8.5 volts across the diode. This may have been overly optimistic, since the driver also needs to be rock-stable at very low currents (such as when driving a blu-ray diode at 100 ma, for example). The testing that will be done will determine if this is actually attainable or not. (Marc Rubin has modeled it in PSPICE, and it looks fine, but the proof is in the hardware...)

Also 10 amps requires *huge* traces. Look at the picture above and you can see that the ouput traces are pretty big. In fact, the distance between the pins on the output transistor is the limiting factor on how big those traces can be. We are reasonably certain that this layout can physically handle 10 amps. So as long as everything else works out, we should be OK. But worst-case, if we have to de-rate the current, we should be able to handle 8 amps for sure. (Which should be just enough to handle your IR-pump diode needs, Eric... )

The driver will run off either 5 or 12 volt supplies. 5 volts will be idea for reds and IR diodes with low forward voltage drops. 12 volt supplies will be required to power 445 blue diodes, blu-ray diodes, and the new 520 nm green diodes, because of the much higher forward voltage drop across the laser diode.

Of course, when running off a 12 volt supply (especially at high currents) you will need to be mindful of the power loss across the output transistor! There will be a lot of heat generated there, and if it's not properly managed, you will cook it. (There will be detailed information on this in the datasheet included with the driver.)

Swami have you scoped the output of all the other drivers?

I have put several drivers on my oscilloscope and fed them square waves. I was quite surprised to see how much noise was present even on very popular hobbyist drivers. I think I understand why I've had so many failures over the years! I'll try to get some pictures next week to explain this further. But yeah, if you are running a diode right at it's limit, all it takes is a little noise and POOF! And there is more than just a little noise on the drivers I've tested.

Also, I should point out that this is not a new problem. Francesco Van Loon did a lot of research for Pangolin on this subject back in 2009, and my understanding is that every driver he tested exhibited problems of one sort or another. And he didn't test just hobbyist drivers. He also tested several commercial units that were quite a bit more expensive than anything you'd find for sale here on PL. But they all had flaws. That's what lead Bill to design this new driver in the first place.

All we have really done is to modify it slightly to support much larger output currents, and also to support higher forward voltage drops across the laser diode. The "guts" of the circuit is still all Bill's design; we left that part alone.

Also, I do need to thank Bill for agreeing to allow us to use his design. Without that, we never would have started this project. In addition, Mar Rubin (Kecked), Mo Ayoub (Daedal), and David Zurcher (DZ) have been very helpful in bringing this project to the finish line. Believe it or not, Mo and I first started talking about this nearly 3 years ago! We re-started the project in earnest back in October of last year, and it's taken us this long just to get to a working prototype.

But we are almost there. Just waiting on a few final components to arrive in the mail, and then we can start testing. Assuming all goes well, then by the end of next week we should be able to send the first batch off to be manufactured.

Adam

[badger1666]

Hi eric
Should have explained better.
Would be nice to see some lights on detailed pics of your setup
Or another one of your excellent videos
Explaining what does what, in the interests of learning

[taggalucci]

Hey Adam

Would you mind letting us know if you've tested a Badpip driver? You don't need to reveal any results, opinions etc. I'm just interested if this was in the list of those you have.

Cheers *

[drlava]

There is a lot of insinuation here, that should be cleared up. With regards to the FlexMod P3 Driver, it has been tested by unbiased 3rd parties and found to perform excellently with no overshoot, hard limiting to the setpoint, and a very high safety performance (the diode can be disconnected and re-connected, WHILE POWERED!). Here is a scope shot of an unbiased 3rd party test who was looking for potential issues:



In it you can see the Yellow trace exceeding 5V, and going below 0V. The output of the P3 is limited precisely at the set current (thus the flat top) and negavite input modulation voltages did not bother it either.

His conclusion: "No signs of the LD current exceeding the configured setting! No signs of oscillation, ringing etc."

The drivers that Francesco tested in 2009 did not include the P3, it wasn't even out yet. The P3 driver was designed to overcome all of the limitations of previous N1 and N2 driver versions. The P3 is such a safe driver that some people run into its autoprotection feature before they even know they have a problem with their circuit! While this has taken time, helping them troubleshoot their circuit, it has saved a lot of diodes.

[buffo]

Re-run that test on the P3 with a higher input frequency, Andrew. You've surely got your own oscilloscope at home.

I have tested the P3 on a 'scope, and at frequencies closer to 20KHz I definitely saw spikes of as much as 20%, and that was on an input modulation signal of just 3.5 volts (square waves, 50% duty cycle). I can post more about this when I get home (including pictures and exact frequencies), but there is definitely some overshoot visible in your driver.

One of the things I built for this driver project was a decent square wave generator (battery-powered, so no interference from an A/C psu) that could handle 2-100KHz with an adjustable duty cycle. This is what I've been using to test things with, and it's very good at finding weak spots. (Unlike the picture you posted, this function generator develops very sharp square waves with no discernible slope on the rising or falling edge. Also, absolutely no ringing even at 100KHz, which is far and away faster than we would ever need.)

And I don't know if you remember this or not, but I tried to contact you several times about a string of failures that I experienced with the P3 back in the fall of 2011, but you never responded. Other people reported similar problems at SELEM last year, which is one reason why this driver project was pulled off the shelf and put back on the burner.

Sorry if this sounds like I'm dumping on you dude. I had planned to do more testing of both the new driver and examples of currently-available drivers before posting about this, but this thread has sort of forced my hand.

Adam

[drlava]

Indeed, I will pull out the scope again, and a sampling of boards. When you test, be sure to measure current diferentially and with your probes properly compensated.

EDIT: I went ahead and captured a test video, because I knew I couldn't sleep unless this was up. During the development of the driver, many many tests were performed to ensure safety and very high performance operation. As you've said before 'this aint his first rodeo'. Due to the high performance nature of the driver, certain installation tips should be followed as mentioned on this forum and in the manual.


The rotation of the video should be fixed soon.
The small 'noise' blips on the scope are due to sampling noise and a local strong radio station.

[polishedball]

Drlava, will the P3 be available again anytime soon? your site has had them out of stock recently.

Thanks

[edison]

Regardless of the Flexmod is working properly it has no standby beamsupression that you need for blue diodes so its a little bit oldschool if you ask me.

More important with any product that someone putts on the market you also need to have distribution capabilities and when looking back both Dr lava and Badpip struggeled with this. Different prioryties from both parties interfeared with the delivery of the drivers. Many people are interested in a driver that can be delivered ready from stock but since most guys here don,t see selling drivers as first priority it will be doomed from the start. They are available maybe on the short therm but as soon as some other things come arround the corner they are not available any more.

What ever driver will be available it should be available for the next 5 years instead of dumping a few on the market.