Bluray Voltages / Drivers

[Tabish]

I'm a bit confused about the drivers.

I understand that drivers are used to limit the current flowing to the diode.
I've also found that blu ray diodes use about 4.5v

The rkcstr driver takes 7-12 v input.
This means that the extra 2.5 - 7.5v (depending on input) is turned into heat and basically wasted energy ???
So 3x 10440 = 10.6v
10.8 - 4.5 = 6.3v of energy turned into heat within the driver????

And how about the flexdrives. Like the one in this mini host:
http://laserpointerforums.com/f39/fs-pocket-mini-build-kit-easy-assembly-22537.html

It runs of a 3v or 3.6v. How does that power the diode???
Are the diodes in the single cell builds being undervolted ??????

 

[jayrob]

Good question...

The FlexDrive is a 'boost/buck' circuit, that uses extra current to boost voltage to the needed voltage of a blu-ray diode in a single battery build. (3.0 volt primary or 3.6 volt rechargeable)

In my new Key Chain CR2 GGW 6X build, the diode is taking 188mA's current, but the battery current draw is 340mA's because the driver is using current to boost the voltage that the diode is asking for...

http://laserpointerforums.com/f39/fs-key-chain-cr2-kit-schweet-42773.html

It is a very efficient driver as well... It will use every bit of battery charge that your battery has before it stops regulating current.

It's also interesting to note, that as the battery starts to drain, the driver will draw even more current to keep up with the voltage demand of the diode. It will have to boost more voltage as the voltage drops on the supply end. It uses current to do this.

So as the battery drains, it must supply more and more current. These things must be considered when building a tiny build such as my other Key Chain (10280 battery) build. (it is recommended to stay below a 2C discharge rate for Li-Ion's) The 10280 is only a 200mAh capacity battery. See some battery current draw measurements on three different diode/power builds using a tiny 10280 supply here:
http://laserpointerforums.com/f38/215mw-6x-key-chain-blu-ray-flexdrive-20124-6.html#post475354
Jay

 

[Tabish]

Woah, wait.
You are saying that tiny "driver" is actually a miniature DC to DC converter!!!

What about the rkcstr, is it a voltage convertor too or simply dissipates extra voltage as heat ???

How do the flexdrive / rkcstr compare efficiency wise???

 

[daguin]

Three fully charged 10440's total 12.6V (4.2V each)

Peace,
dave

 

[jayrob]

Dave, I have fielded this question a lot, and I just messaged rkcstr about it, but do you know if people are using 3 X 10440 supply with a rkcstr?

Because as we know, the rkcstr is 12 volt max supply... but, I'm sure the 12.6 volt at full charge will very quickly drop to 12 volts or lower with a load.

Just wondering if you have heard if people are doing this, because it seems that only 2 X 3.6 volt rechargeable with a blu-ray/rkcstr build, would soon drop below the needed supply voltage??

Anyway, I get these questions a lot, but since I have not used rkcstr drivers yet, I'm always just giving the same explanation that I just wrote, and just recommending to check with rkcstr...
Jay

 

[jayrob]

Woah, wait.
You are saying that tiny "driver" is actually a miniature DC to DC converter!!!

What about the rkcstr, is it a voltage convertor too or simply dissipates extra voltage as heat ???

How do the flexdrive / rkcstr compare efficiency wise???

I believe extra voltage as heat, similar to a DDL driver...

Both drivers are very high quality,

Here's the documentation:

rkcstr:
http://rkcstr.googlepages.com/MD_v3_inst_rev1.pdf

FlexDrive:
http://hacylon.case.edu/ebay/laser_diode/MicroFlexDrive User Manual.pdf
Jay

 

[Tabish]

Thanks for the link to documentation.
The flex drive seems nice. It says 80 - 95% conversion efficiency.

Here's another question.

If the flexdrive draws extra amps to "boost" the voltage.
Does the rkcstr draw extra voltage to boost the amps ???

Or does the draw current have to be same or over the output current
So basically its not converting extra voltage to extra amps but simply wasting the extra voltage.

 

[jayrob]

Thanks for the link to documentation.
The flex drive seems nice. It says 80 - 95% conversion efficiency.

Here's another question.

If the flexdrive draws extra amps to "boost" the voltage.
Does the rkcstr draw extra voltage to boost the amps ???

Or does the draw current have to be same or over the output current
So basically its not converting extra voltage to extra amps but simply wasting the extra voltage.

You'll have to check with rkcstr, but I believe any extra voltage gets wasted as heat, similar to a DDL Driver. (LM317 based)
Jay

 

[Tabish]

Ahh ok. I am not familiar with the DDL driver (or any other driver really lol)
I'll ask rkcstr about it.

 

[blue lasers]

Dave, I have fielded this question a lot, and I just messaged rkcstr about it, but do you know if people are using 3 X 10440 supply with a rkcstr?

Because as we know, the rkcstr is 12 volt max supply... but, I'm sure the 12.6 volt at full charge will very quickly drop to 12 volts or lower with a load.

Just wondering if you have heard if people are doing this, because it seems that only 2 X 3.6 volt rechargeable with a blu-ray/rkcstr build, would soon drop below the needed supply voltage??

Anyway, I get these questions a lot, but since I have not used rkcstr drivers yet, I'm always just giving the same explanation that I just wrote, and just recommending to check with rkcstr...
Jay

my pocketpal uses rkcstr driver with 3 10440 batteries and when they are fully charged the laser is working fine.

 

[daguin]

Dave, I have fielded this question a lot, and I just messaged rkcstr about it, but do you know if people are using 3 X 10440 supply with a rkcstr?

Absolutely! Only one component on the Rkcstr is rated at 12V. IIRC everything else is rated for at least 16V. As we know, electronic components will usually do more than than what they are "rated" for. We do it all the time. However, we also know, we do so at the component's peril

Peace,
dave

 

[jayrob]

Thanks for that feedback guys...

I figured it would be ok for the rkcstr driver, it's not going to be 12.6 volts for very long at all with a load...
Jay