Flexdrive Acting Like a Linear Drive?

[daguin]

I have been monitoring the output of my 4X/6X more closely than I normally monitor the output of my lasers.  This is because we are still trying to ascertain a "safe" current for them.  I built one into an MXDL "chicken leg" (DX, 3405) using a flexdrive, a Merideth glass lens, and powered by three AAA's (Duracell, Copper Top).  I set the driver at 210mA.

The laser started out at 180mW.  Then it started a slow decline in output.  I was half expecting it to do this based on some of IgorT's work.  It slowly "degraded" down to 135mW and then blinked out. I was sure it had died.  However, as is my usual routine, I replaced the batteries before going on to the next step in it's demise (I learned this the hard way).  To my surprise, with the new batteries, it is still lasing AND it is now back up to putting out 180mW!

I thought that the flexdrive would hold the current constant until the lower limit of the voltage was reached.  Was I wrong?    I don't remember observing this sort of output decline in any other lasers using the flexdrive.  In addition, if this is the case, this diode/driver combination is draining the batteries very rapidly.

Peace,
dave

 

[brtaman]

Hey daguin,

That seems pretty strange. A driver like a flexdrive should in theory and practice hold a constant current right until the minimum voltage.

However, is it possible that the batteries were just a "bad batch" and were not able sustain the flex to do its magic? I have gotten "bad" alkaline batteries before. Perhaps, try using the "bad batteries" in another one of your many builds to see if it is indeed the batteries causing the problem?


thanks
brtaman

 

[jayrob]

Dave, I'm sure you checked other things like the battery connections in the battery holder...

Some people swear by Duracell. I have never liked them. It seams like when ever I picked up a flashlight to find the batteries dead, they were that brand!

I have noticed that Energizer Alkaline batteries last much longer. e2 Lithium even better!

This is why I doubt it was the driver, more likely the batteries...
Jay

P.S. I got 183mW's @ 210mA's with my GBW 4X with a Meredith glass lens (FlexDrive). Very much the same!

 

[drlava]

That is not normal operating mode, it might drift a few mA but shouldn't go that much.  Try adding a small approx. 10uF capacitor in parallel with the part that is right next to the battery connections on the driver.  Is this a V2 driver? They were more sensitive to battery resistance in some cases than V1 and the currently shipping V3.

The E2 lithium batteries, as long as the voltage is right, should have a lower all around series resistance than the 'regular' alkalines.

 

[daguin]

That is not normal operating mode, it might drift a few mA but shouldn't go that much.  Try adding a small approx. 10uF capacitor in parallel with the part that is right next to the battery connections on the driver.  Is this a V2 driver? They were more sensitive to battery resistance in some cases than V1 and the currently shipping V3.

The E2 lithium batteries, as long as the voltage is right, should have a lower all around series resistance than the 'regular' alkalines.

This is a V2. I'll try switching out the batteries first. It's already in a host.

Peace,
dave

 

[ndrew2505]

ive got a v2 driver in my sonar II case that i tested the other day with some batts that had been in there for a while and the phr diode tested around 70-75mw with my laserbee lpm. i retested today with some newer batteries today and got 160mw with the same driver/diode setup.

both tests were done with these batts but the first set i used were more depleted than the others i used today: http://www.dealextreme.com/details.dx/sku.14