micro boostdrive vs flexdrive from 18650 driving 445nm LD

[ossumguywill]

Lol just make a test load.

 

[Xplorer877]

No it's not linear. If you had it set to 950mA why would you want to turn it up? You'll never notice a difference in brightness or burning power with and increase of 50mA when the power is already very high. I've read that it's even hard to tell the difference between a 250mW 405nm and a 500mW without smoke. The eye's sensitivity to brightness is diminished when the lower intensity source is already too bright to look at. It'll be like looking at two suns, one of which was 25% brighter, it'll actually be very hard to tell. If you're just experimenting then know that these little potentiometers are NOT meant for constant adjustment. The one on the Flexdrive is only good for about 25 adjustments, the one on the Boostdrive will last longer but they're still not meant to be constantly adjusted, especially when current is flowing through them.

-Tony

 

[drlava]

Can I measure current to the diode by setting my DMM to measuring current and then putting the DMM pins across the diode + and - pins? Is that safe?

NO! The multimeter must be in series with the diode to make that measurement!

Hey DrLava. Just wanted to get your official word on the matter.

The official word is that the amount of variation is more or less unknown, but typically less than 20%, around 10%. Use a dummy load.

 

[Elektrotechniker]

Clockwise increases the current. There is no guarantee and you can damage the pot if you turn it too far. You should use a dummy load.

Get 4 1n4001 diodes in series with a 5W 1 ohm resistor and measure the voltage across the resistor, 1mV equates to 1mA.

-Tony

Don't we need 6 diodes for 445 ?

 

[laser_freak]

Don't we need 6 diodes for 445 ?

Yes. The 445nm diode has a voltage drop of about 4.2V at 800mA. 1N4001 diodes have a voltage drop of 0.7V.
4.2 / 0.7 = 6

However, the 1 ohm resistor will also drop the voltage a little, so maybe only use 5 diodes.

 

[drlava]

Don't we need 6 diodes for 445 ?

Yes. The 445nm diode has a voltage drop of about 4.2V at 800mA. 1N4001 diodes have a voltage drop of 0.7V.
4.2 / 0.7 = 6

However, the 1 ohm resistor will also drop the voltage a little, so maybe only use 5 diodes.

NO! 1N4001 diodes have a variable voltage drop depending on current. At 1A they drop about 0.9V! this plus the resistor (which should be 2 1 Ohm resistors in parallel for 0.5 Ohms total) is why I suggest the red dummy load range with 4 diodes.

 

[laser_freak]

NO! 1N4001 diodes have a variable voltage drop depending on current. At 1A they drop about 0.9V! this plus the resistor (which should be 2 1 Ohm resistors in parallel for 0.5 Ohms total) is why I suggest the red dummy load range with 4 diodes.

Oh, thanks for the info.

Also, I accidentally shorted out the output pins on my boostdrive while it was powering my diode. A puff of smoke came up from the board, and the driver no longer works. Do you know which component was likely fried so I can replace it without buying a complete new boostdrive?

 

[drlava]

Yes, it was likely the switching diode (top side, near D+) send $3.30 through paypal and I can mail you a new one.

 

[Scross1220]

Dr. lava

I have my Microboots drive rung at 1000ma within a MXDL 3405 build. I seem to be overheating at this level and I am running with a AW 18650 battery and a 445nm 1 watt LD. I have. Tried different grounds either by LD case or - battery and the LD begins to flash after 1 minute. At 1100ma It starts to flash in 30 seconds. What can I do to fix this. Last bit of info. The LD is soldered to the driver. Any help would be great.
Thanks
Steven

 

[ossumguywill]

You either need to charge the battery or better heatsink the driver. If the driver gets too hot, it might flash.

 

[Scross1220]

It's definitely a thermal issue. I am not sure how to heatsink the driver. The batteries are ok when i tested the voltage which is around 4.0v. Does it mean I should unsolder the LD and mount the driver below or. Can you suggest a better idea. I have a MXDL 3405 modified to use. A 18650 battery.
Thanks

 

[ossumguywill]

OK, so basically to heatsink the driver, you have to stick it to a metal surface (like the pill of the flashlight) with nonconductive thermal paste or thin thermal padding (available on ebay). I used both in my build, the microboost stays steady at 1200+mA, and I've never run it for more than a minute because the laser gets too hot, but there's no flashing at all. I would recommend something like
Thermal Grease Paste Compound Silicone fr CPU Heat Sink - eBay (item 390166457118 end time Sep-02-10 14:13:17 PDT)
or
Thermal Pad 3cmx3cmx0.5mm CPU GPU DDR RAM CHIP XBOX360 - eBay (item 270622153143 end time Sep-13-10 11:51:26 PDT)

total cost, < $5. I think those are the exact 2 products I used, you really only need one of them. You might have to de-solder the driver and use wires to go to your diode, I've never used the 3405 build.

 

[Scross1220]

Excellent. That is the info i needed. I'm all about getting these items quickly.
I just ordered both of the on bay.
Thanks for you hep.
Steven

 

[ossumguywill]

No problem. Good luck with it!

 

[Scross1220]

I moved the LD off the driver and moved the driver to the pill. A fried of mine suggested I glue it in with some high temp RTV silicone that way I can remove it if I have to service it. Don't worry the pot side of the board is not exposed to the silicone so I can still make adjustment. What do you think will this work?

 

[qumefox]

It will if you use thermally conductive RTV.