I just put FoulMisT's FMT driver on an oscilloscope...

I will wait for Tomas to look over the images first, but let me just say it was a pleasure to see it perform. From my initial impressions, it was exactly what you would hope for! Hopefully he will post soon...

:eg:

It would be helpful to the members that may not know
what a "foulmist" Driver is to link to it or explain if it is
a Linear or Buck Or Boost driver...

I'd like to see the Scope pics when your ready...


Jerry

You can contact us at any time on our Website: J.BAUER Electronics

Good idea Jerry! Here is a link to the driver...

http://laserpointerforums.com/f67/new-buck-boost-high-output-driver-69959.html

I'm ready to post, but I thought that I would let Tomas see them first. Just as a courtesy. I don't think he would mind, as the results looked pretty good to my untrained eye. I'll give him a little more time to respond.

That's great, but I really hate these silly "preview" clutter posts that contain no good information. Even worse, this one isn't even a "preview" post: it's a hope-someone-else-will-post-results-but-I-was-involved post. Your OP probably should have been a reply to foulmist's original thread, not a new thread.

Well, to be honest when I PM'd him, it said he was online so I expected it to only be a matter of minutes. Clearly the green "online" signals don't mean anything. Sorry to have bothered you.

But it isn't a hopesomeoneelsewillposttheresults, it is a "I wanted to be courteous and wait until he had seen the results first." Just to be clear.

Hey sorry, I wasn't online at that time. I just entered.

Sure you can post them,

I just want to say that these are the first revisions that Tom scopped which made it to production.

I am expecting the new ones in a few weeks. Which are better. I will send one to Tom to scope too for comparison.

These are mainly for the 445nm diodes. But they will be available for the High current Mitsubishi reds too.

tsteele93 said:

Well, to be honest when I PM'd him, it said he was online so I expected it to only be a matter of minutes. Clearly the green "online" signals don't mean anything. Sorry to have bothered you.

But it isn't a hopesomeoneelsewillposttheresults, it is a "I wanted to be courteous and wait until he had seen the results first." Just to be clear.

Click to expand...

The Green ON LINE means nothing by itself... You also need to
go to the member's Profile/Statistics and see what time his Last
Activity was.

foulmist said:

Hey sorry, I wasn't online at that time. I just entered.

Sure you can post them,

I just want to say that these are the first revisions that Tom scopped which made it to production.

I am expecting the new ones in a few weeks. Which are better. I will send one to Tom to scope too for comparison.

These are mainly for the 445nm diodes. But they will be available for the High current Mitsubishi reds too.

Click to expand...

Better in which way.... Specs/Noise/Size/etc...:thinking:


Jerry

You can contact us at any time on our Website: J.BAUER Electronics

It's 15.8mm instead of 16mm
it's layout is slightly changed for better heatsinking of the resistors.

also the output ripple is brought down to minimum. (will see on scope)

A/C Ripple +30mW / -34mW total 64mW by tsteele93, on Flickr


FMT 1.75A driver - startup by tsteele93, on Flickr


FMT 1.75A driver - single trigger startup waveform by tsteele93, on Flickr

Ok, the good...

This driver is rock fricking solid. It goes straight up to 1.74 amps and sits there with about a 60mA ripple, which means only 30mA over the 1,740mA output. So at most, 1.77A. That seems pretty good to me.

I would assume that would mean at 500mA (where I was testing the Benboost the other day) you would be looking at maybe 22mA ripple and ~10mA over the rated output? Just using rough numbers in my head.

That is excellent. For a 445, that is NOTHING as far as ripple. I don't know if this can go high enough to drive a 12x 405 but even a sensitive diode like a single mode should be ok with this driver. No spike on startup and very small ripple.

Now the tradeoffs...

That sucker gets HOT FAST. It needs some solid heatsinking. Of course this is probably true of any 1.75A driver.

Also, it takes an evil power source. I was only getting 1.3A out of it with some very good (but protected) batteries and it wouldn't even go over 1.3 with my PSU! I finally got 1.74 out of it with a red AW IMR 18650. Even then, if I put it in the same battery case that I used to test the benboost, it would drop down to 1.6A. I could only get 1.74 if I mashed the wires up to the battery itself. (I kept praying it wouldn't explode! )

One of my cheaper batteries even got the audible high frequency squeal out of it - which I can still hear, thank you very much! That is mentioned in the VERY GOOD instructions that come with it.

Overall, a very nice single Li-ion driver with very little ripple and no spike on startup at all!

:beer:

P.S. here is the link to the Flickr gallery with my comments...

http://www.flickr.com/photos/tsteele93/sets/72157630135774346/

Your display looks too irregular and random to be ripple. Ripple should be at the switching frequency of the driving FET. Adjust the time-base to something closer to the switching frequency. Probably somewhere in the 10-20µs range.

A lot of that "ripple" you see could just be noise in the scope leads. What does it read when the power is off?

60mA ripple? WTF? That is a lot isn't it? You've got to be making an error somewhere...

Ok, what do I need to set the timebase? I think he is using the TPS63020 IC and I think that is 1.6Mhz. Would that be 0.625uS?

Would I be better off using a HF Reject or LF Reject setting to try and get rid of noise?

EDIT: I stand corrected, 2.4Mhz. So that would be ~0.4uS? (roughly?)

Tps63020 is at 2.4mhz

So should I set the timebase the same as the period, or should it be higher by some factor?

Well I'm sure you know more about it than me, but I would probably do 1/2 or 1/4 so the wave is bigger and you can see it in more detail.

I don't know SQUAT! LoL! I'm reading the manual like crazy to understand this thing. I'm not sure that I'm the best choice for this right now, but Tomas asked me to scope it and I gave it a shot. I still have a ton to learn.

I did the benboost shot at 50uS. I'll try this at a couple of timebases and see if any of them make sense.

The only thing I don't understand, is that my inexperience aside, what can I be doing wrong? Isn't the scope showing what is happening? I guess using the wrong timebase doesn't give a clear picture but isn't it still the correct numbers?

Oh well, I'll try it at 50uS and lower if it will let me and see what it does.

:beer: