Issues with MicroDrive?

I'm having issues with my microdrive - it is being driven off 3 AAA batteries (4.5v), set at the max of the low-range mode, and my diode has dimmed since i first used it - it no longer lights matches or flouresces stuff as powerfully. I desoldered it, and wired it up to a test load, and now, as soon as I connect the batteries, the output current peaks at 150 or so mA before dropping rapidly to around 80. Is there a reason for this? The batteries measure around 3.4V currently. It's been in a Pocket Pal style build, working OK for a few days.

I don't think the diode has burnt out as it was running in the low-range, giving 150mA when configured for Red (My mistake when building, I only recently realised), there are no beam artifacts, the shape hasn't changed, the heatsink is quite large, I've been running on a duty cycle of approx. 3 minutes, it never felt even warm, and it still lases. Could the cheap tail-switch on the DX hosts cause this problem (back EMF)? If not, what's the problem with my MicroDrive?

Hmm.. Does the dot look less than the dot of a cheap laser pointer you would get from a gas station? Also, your supposed to have more than 4.5v going to the driver.

on his website it says

"This driver is based on a linear constant-current-output (CCO) design which regulates the current output delivered to the load (laser diode), no matter the output voltage. What this means is that your laser driver will be powered with the current of YOUR choosing and will remain stable as long as your input voltage is AT LEAST 2.25V higher than the output voltage (the laser diode's operating voltage)."

A red laser diode runs at 3v (if I remember right) so you will need AT LEAST 5.25v, 6v-9v should be sufficient. I have been running a laser diode at 380ma with an input of 9v to the driver. (6aa batteries) It has lasted forever.

Just to clarify, this is Lava's Micro FlexDrive I am referring to, sorry if I wasn't clear.

charlie bruce said:

Just to clarify, this is Lava's Micro FlexDrive I am referring to, sorry if I wasn't clear.

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Three suggestions:

1) clean ALL the electrical contacts: battery connections, screw threads, carriage connections, tail switch, springs, etc.

2) test the output of the flexdrive with a bench type power source.

3) get higher quality batteries.

Peace,
dave

A replacement of batteries seems to have done the trick but I thought the MicroDrive was not meant to behave in this way? I was under the impression that it would drain the batteries right down to 2.4V and not have "drop-out" issues. Any insights?

charlie bruce said:

A replacement of batteries seems to have done the trick but I thought the MicroDrive was not meant to behave in this way? I was under the impression that it would drain the batteries right down to 2.4V and not have "drop-out" issues. Any insights?

Click to expand...

Yeah.  Sometimes the batteries get right on the edge.  They are still putting out the required voltage, but there's not enough left in them to provide the needed current.  Also, sometimes a single battery is failing and beginning to short out. You have learned the first lesson about boost drivers . . . .

Always change the batteries first

Yeah.  I learned that one the hard way too, but I learned it on a $285 diode  :-[

Peace,
dave