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DC/DC boost drivers question

lazerov

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Button?? You mean like a small clicker button for pen hosts ??
Fixed. I meant "switch"
Btw, I assume it can fit inside the aixiz module ?
No idea, I don't have any Aixiz modules. The PCB is 20mm long and 9mm wide.
Last question, is the current the output current? (as in what the diode receives)
The current setting resistor determines the output current (to the diode).
 

Tabish

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I ordered 2 of these drivers.

I also spoke with someone at rayfoss.

He said he will talk to the engineer about the 47nF cap and hopefully he will find some and include them for me.

PS: I was told the resistor is fixed at 0.112V not 0.120V


As for the cap, it is placed between diodes + and - terminals ???
 

bryce007

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I ordered 2 of these drivers.

I also spoke with someone at rayfoss.

He said he will talk to the engineer about the 47nF cap and hopefully he will find some and include them for me.

PS: I was told the resistor is fixed at 0.112V not 0.120V


As for the cap, it is placed between diodes + and - terminals ???
Just curious, did you get a response from rayfoss after placing your order? Or before? I emailed them three times over the past three weeks asking about these drivers, and they seem to be ignoring me. Were they willing to set them at your desired current?

You can cut that pin and solder the + wire directly to the driver.
You risk breaking bond wires when bending/cutting off diode pins.
 

Tabish

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Ya, they respond very quick. And yes they will set the current.

Perhaps you are sending to the wrong address.
 

bryce007

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Ya, they respond very quick. And yes they will set the current.

Perhaps you are sending to the wrong address.
no I had it right. So did you get answers before and after ordering? Or just after ordering?
 

Tabish

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I never ordered through the website. I sent an email and got a quick response. Couple email exchanges later, I payed through paypal.

Btw, don't order through the website since they charge 3$ for shipping for EACH item.

So 9$ shipping for 3 drivers.

Send them an email to specify desired current and they will ship them together.

Mine are shipping on oct 5th. (chinese holyday delayed it)
 

Tabish

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Are there any boost drivers that have a size comparable to that of the FlexDrive?
I dont think so. The rayfoss driver is 20mm x 9mm i believe.

I know IgorT makes better drivers than flexdrives. Not sure about their size.
They are pricy though.
 
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drlava

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According to Igor, starting with the V4 the current output stability over the range of battery charge is excellent, I think you are referring to old data about the V1-3. For the earlier models, it was still very good but did vary up to 15 mA in some cases. Either model would be much better than the rayfoss ones you link to.
 
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IgorT

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How many good/small ones exist?
Such as the flexdrive.

Is there a cheaper alternative for the flexdrive???

No offence Dr.lava, you got an awesome driver, but it's really pricey for me.

Tabish, the FlexDrive is a good affordable laser diode driver at this price!

The majority of people here don't know how much work goes into the developement, testing and troubleshooting of a driver, before it works as it should! How much special equipment Lava needs to test them to make sure your diodes are perfectly safe! Never mind how much he had to learn about electronics FIRST!!!


Then you also have to realize that the parts on these drivers are NOT cheap! You need some expensive special IC's and coils (and other smaller parts), and Lava has to buy large amounts of everything at once to reduce the cost of parts and labor for assembly in a factory, if he wants to make ANYTHING on his design at all!


I make similar drivers myself by hand, and it's NOT FUN!!!!
I am happy when i can buy a FlexDrive, and use that instead of my driver, simply because i don't have to put all that work into it (with a ready-made driver, i can make a build for less)!


With the forum offering so many ideas, and different designs, you have the possibility to build an awesome laser - one you could never make yourself, if someone didn't spend A LOT of their time and money on developing it), and i think the cost of a FlexDrive is not unreasonable!
 
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IgorT

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I know IgorT makes better drivers than flexdrives. Not sure about their size.
They are pricy though.
I don't make better drivers, i make specialized drivers, optimised for 405nm diodes ONLY! (Size is the same BTW...)


My driver for example can not power a red, because it's just a boost driver in this version (- the full SEPIC version is too big for my needs but fits an AixiZ module), but will keep a 405nm diode at a current that never changes more than 0.2mA (often less) from a full to empty Li-Ion (or <0.3mA from 4.5V down to 2.2V, when tested from my PSU)...

What that means is, that the current through the diode will always be the "same" (it will slowly drift down by 0.2mA as the battery goes from full to empty - a drift barelly worth mentioning).. So the starting power will always be the same as well.... The drawback is that it can't power red diodes in it's current version, nor does it have a pot (but that's on purpose and there is an option WITH a pot). I made it for my lasers, and i'm happy with it.


When i need to make a red, i always use a FlexDrive, i bought many from Lava in the past. I have used a few with BluRays as well, but had some bad experiences with an earlier Flex version (was it v2?) and a PHR set just below a kink (complicated story).. But with improoved stability of the latest Flex and 6x's and 8x's having no kinks, that problem can't repeat itself anymore...


In the latest version, the FlexDrive was redesigned, improoved and made much more stable than before (less current drift), through the selection of more expensive components with better tolerances and better positioning.


And then people complain about the price of it? :thinking:

If i didn't know how to make my own driver, i'd be extatic about having the possibility of buying a tiny driver, so that i can make a small laser working off a single battery - my wish for "small but powerful" lasers was the sole purpose i started working on buck/boost drivers in the first place!





According to Igor, starting with the V4 the current output stability over the range of battery charge is excellent, I think you are referring to old data about the V1-3. For the earlier models, it was still very good but did vary up to 15 mA in some cases. Either model would be much better than the rayfoss ones you link to.
Yes, the latest drivers are much better, than the first i've seen (v2)...

The first ones scared me, cos they didn't like my switching PSU (even tho i filtered it heavily), and i was not even able to test the stability until i put together a battery powered adjustable voltage source.. Then the abnormal operation stopped, and from batteries, they worked well enough.

Adding a few caps on them doesn't hurt either, and i made it a habbit to increase the input and output capacitors, just in case..
I also noticed, that the addition of the right value input capacitor reduces the battery voltage related drift with some of the earlier versions IIRC.

But the v4's i'm quite happy with! Still adding caps just in case tho.
Better safe than sorry.... :angel:




I meant, Igor's driver is MUCH more stable. The output current is more constant from full battery to dead battery.
There are also virtually no spikes.

Ask IgorT about it.
What are you talking about when referring to spikes? And what do spikes have to do with stability?

Every driver HAS to be made in a way that it doesn't have spikes at power-up!



Lava and i talked a lot about drivers, stability and testing them, how to prevent possible accidents from abnormal operation (or abnormal use by the builder) and such...

You can be sure Lava knows what he is doing. He simulated pretty much every possible condition that can occur in a laser, when testing his drivers on a scope, before releasing them for sale!


I got one of the first v4 prototypes, and i have to say i was very happy with it, when i saw the stability was improoved compared to earlier versions! Even better, now i don't have to make two different heatsink versions anymore, since the new Flex is now the same size as my driver...
 
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IgorT

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So IgorT, where do you sell your driver and how much?
I don't sell my drivers outside of my lasers... They are too hard to make by hand. I'd have to have 1000 pcs manufactured in China, if i wanted to sell them! And that requires painful amounts of money for all the expensive little parts!


I once proposed doing a GB for kits for the drivers, when i got my version up and running, upon which Lava said that the Flex is coming out soon anyway, so i kinda lost interest in the kit idea after that...
 




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