Making your AixiZ driver work. The solution!

[rhd]

I'm hoping someone can clarify some fuziness for me -

1) I've never quite understood what TTL+ implies, differently than simply the battery (+). Why are there both on this driver?

2) If I want to supply an LPC-815 with ~400mA off a single CR123, will this driver do it? I have 4 of them that I haven't put to use yet. Or do I need to go the more expensive route of a flexdrive or microboost?

3) Is the battery (-) and diode (-) continuous ?

 

[Coherent Light]

rhd the table that is in post #1 shows that with one fully charged CR123 you'll get ~144ma. You need 6v to get the full output. The TTL+ needs to be tied to the drivers VCC+ anything between 2v & 6v will allow the diode to power on. If you go higher than 6v in you need to put a diode in the path to drop the voltage to 6v or lower. TTL is used to turn the laser on & off remotely.

Vcc---------Voltage Out () Max Output (1mv = 1ma)
3VDC----------2.9VDC-----------27ma
3.5VDC--------3.1VDC-----------76ma
4.0VDC--------3.3VDC----------144ma
4.5VDC--------3.5VDC----------226ma
5.0VDC--------3.6VDC----------310ma
5.5VDC--------3.6VDC----------400ma
6.0VDC--------3.75VDC---------430ma

 

[rhd]

Ok - that's what was confusing me. I had messaged them on eBay some time back to ask whether 1x18650 could power a 405nm 12x diode at 500mA with this driver. They said yes. But clearly that is not the case.

I take it there is no boost function to this driver.

May I still ask -

1) What does TTL+ imply / mean ?
2) Is the battery (-) and diode (-) on this driver continuous?

Thanks for your help!

 

[Coherent Light]

TTL = Transistor Transistor Logic. I would have to Ohm it out for sure, but I think VCC- & diode- are continuous. TTL is used in projectors and in labbies, but DTR used a led driver that had modulation Ie. On & Off at a certain frequency "same concept as TTL"

Does this help or not?

This is a linear driver, and will not boost voltage.

 

[rhd]

I'm getting there, lol!

I'm still a little fuzzy as to what it does. Is it PWN? Or maybe the question I should have asked - if I'm using this driver in a handheld pointer, would want to use TTL+? (Is a Microboost considered TTL? When I create LM317 drivers, are they TTL?)

Another follow-up: How can this be considered a constant-current driver, if as the voltage in the supply cell drops, the current drops too?

 

[Coherent Light]

It has to use the voltage to supply the correct current, so that as the voltage drops it cannot supply as much current {That a simple way to look at it}. You don't want to use TTL in your handheld, but it's a feature of the driver so You have to deal with it. If TTL is <2v it inhibits or switches off the output to the diode, and if it's >2v it switches on the output. The TTL circuit apparently cannot handle more than around 6v, so it needs to be between 2v-6v to switch on the output. By tying the TTL+ to the VCC+ when You hit the clicky it supplies power to both places, and you get a nice laser beam.

 

[rhd]

Thanks for the clarification.

Hypo:
I've made an LM317 powered by 3x10440. Those cells in series fully charged, should supply around 12V. If I set my LM317 circuit to provide 750ma, it continues to supply 750ma even as the cells start to loose voltage. Even when they fade to 10V, there's still 750mA.

Why is this scenario different than with the Aixiz? Is it just the fact that we're dealing with 12V which is so far above what the diode needs ?

 

[Coherent Light]

I'm not sure what the Max voltage in is on these, but as long as You have 6v or greater up to the max the output will be ~420ma. These are not ideal for 405/445 as the voltage they require is higher than say a Red. The driver can only supply so much voltage and current based on the input to the driver. It is basically like your LM317, as long as it has enough input it will output the correct amount. The 12v to your LM317 is a bit of overkill as you can get away with around 7v, so that until you drop below 7v your output stays steady.

 

[rhd]

Thanks for all your help here - It is all completely clear to me now.

What really confused me initially, was that table of values that accompanied the driver. It gave me the impression that we were meant to set current output by adjusting the voltage input - which seemed completely silly.

It appears that really the table of values was just meant to describe what happens to the output current, when the input voltage is below the optimal (6+ volt) level. Since in reality 90% of us will be driving these with 2x rechargeable lithium ion cells, we'll never have to worry about that lower voltage behavior.

Basically, using 2xCR123s, I'd set the current via the pot, and expect it to stay there as long as the cells had a decent remaining voltage above 3v each.

 

[Coherent Light]

That would be correct.:yh: You'll notice the power drop off when your batteries go below 6v.

 

[Vaporizer]

Ok, let me see if I can help a little. I didn't get notified there was a question by email. Sorry.

If you plan on using this driver you have to have power to TTL. No power to TTL and it will not turn on. Consider it an electronic on/off switch. You can use a regular switch, but this one will need to be on. That's why I said it's kinda backwards to industry standard for a laser driver like we use. It's normal TTL characteristics, but if it were true TTL the 6+ vdc should have killed it.

All the readings are with the pot at max. So, you can adjust below the reading for the posted voltages.
A true TTL (at one time) was 5v +/- .25v. That isn't true with this driver.
That is the very reason a computer power supply has such a closely regulated 5vdc. Some parts are CMOS and can operate from 3-18vdc. there semi conductors have ranges depending on the part, material and support components.

As far as max voltage....I still cannot say. Mine took 8.4v and lived. Taking .7vcd off that as I described using a diode(forward voltage drop) for the "TTL" still puts 7.7vdc on the "TTL" and in reality a true TTL would have fried. All the drivers seem to have diff part codes so I can't identify what they actually are. NPN, PNP, FET.......???????

No company posts actual schematics, or at least very few. I took it way past the posted limits to test it. Seemed reasonable to stop at 2 cells. It may very well handle more input voltage, but you'll need to keep some things heat sinked or it will die as the extra voltage will be converted to heat at some point. It, IMHO, acts a lot like a complex linear type driver. It's even using a surface mount LM358.

I hope this helps answer your questions.

 

[rhd]

Would it be too simplistic to say the this driver probably has similar use cases (as far as handheld pointers go) as a Groove V2 Driver?

 

[Coherent Light]

Vaporizer I wasn't trying to take over your thread. I was only trying to help out.:beer: I really do appreciate all of your hard work on these drivers.:bowdown:

Yes it's like a groove v2

 

[Vaporizer]

No problem at all CH.
All I did was try to define it a little better for more understanding.

@ rhd,
If you look at post #9 I stated "@ 7v it cranked out 691ma @ 4.27VDC". Ok, looking at the table I posted of voltages and currents, this has somewhat of a voltage limiting on the output. Raising the input may kill it and will create heat to deal with. But, as you can see the output voltage doesn't raise but very little.

All in all ....it's a $4 driver that works well on reds. Should work on IR(green) too if you so desired. Look at the diode requirements and if its going to take more voltage than what I have on the table, use a different driver. I think the table shows this drivers features. If you put 12v in, I seriously doubt if more than 5v will be on the output.

My main goal was to get it to work and explain what it took to do so. Well, it went a little deeper as it is a dual range driver and works far beyond the specs AxiZ is provided by the manufacturers.

 

[123splat]

Just a NOTE: The TTL connection id NOT an ON/OFF switch, it is a Modulation input. With the TTL floating or tied to ground, the driver still supplies a small amount of current to the LD +&- pads. I got a couple of these drivers from a place called LaserPartsSurplus.com. I tied a hefty red LED across the LD +&- pads and applied 3 Vdc from a bench supply. The LED glowed dimly. I shorted TTL to Vcc and the LED fired up at a respectable brightness. Did the samething at 4.5 Vdc, got the same results. pulled power and swapped the LED with a 405nM low current LD (yeah, I know, wrong driver, wrong voltage, ect.) re-applied power, TTL open, no lase. Tie TTL to Vcc and it lsaes! Switched up to 6Vdc supply and same results. Runs about 40 seconds before getting warm (in an Aixiz with a plastic lense). Tieing TTL to Vcc at 6Vdc doesn't sound like a good idea to me, but it works and driver and LD still in good shape. I suppose that if you wanted to use your LASER as a signal transmitter, you would apply your signal intelligence, at TTL levels, to TTL. Design you own reciever (photo pin, light sensitive photo transistor,?? beyond me for now).

 

[Helios]

If your using a single li-ion cant you just jump the TTL to the + terminal? Wont that voltage fall in the correct range?