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FrozenGate by Avery

micro boostdrive vs flexdrive from 18650 driving 445nm LD






ossumguywill said:
Are you sure? According to lava, using only two of those resistors gives you 1200mA.
Click to expand...

I'm just going by what Andrew told me. It's a complicated circuit. Perhaps they're not all wired in parallel. Unless I can see the schematic I don't know how it works, it just does. :na:

-Tony
 
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Which way do I turn the pot on this (microboost) to increase the current.

Lets say mine is set for the highest range. If I turn it all the way, is it guaranteed to be at 1000mA ?

Is there a limit to how far the pot can be turned or does it loop (hit the max, then drop to min if I keep turning it in same direction)
 
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
 
The pot does not loop, it does have a stopper. When my boostdrive is set to max (not with the custom configuration, but with the standard 1A max) it usually outputs 1.044 A. Close enough.
 
laser_freak said:
The pot does not loop, it does have a stopper. When my boostdrive is set to max (not with the custom configuration, but with the standard 1A max) it usually outputs 1.044 A. Close enough.
Click to expand...

Thanks, just the answer I was looking for.

My reason for asking: I asked it to be preset at 950 but I may change it a bit.

1 more question: How much does the pot turn in total from one end to the other ?

I mean lets say it's set to max-clockwise (1A). If it's turned counter clockwise till it reaches about 540mA, how many turns is it ?

360 degrees? 180? 720?

I know I can always use a testload but I just want to be able to approximate for quick adjustments.

There is no way I'll burn the diode anyway, since its a 140 which can handle much more than 1A. Also, the range will be preset to 540-1000.
 
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Tabish said:
Thanks, just the answer I was looking for.

My reason for asking: I asked it to be preset at 950 but I may change it a bit.

1 more question: How much does the pot turn in total from one end to the other ?

I mean lets say it's set to max-clockwise (1A). If it's turned counter clockwise till it reaches about 540mA, how many turns is it ?

360 degrees? 180? 720?

I know I can always use a testload but I just want to be able to approximate for quick adjustments.

There is no way I'll burn the diode anyway, since its a 140 which can handle much more than 1A. Also, the range will be preset to 540-1000.
Click to expand...

The pot rotates 270 degrees.
 
Tabish said:
The current change (mA / degree of turn) is linear ?

(last question I swear lol)
Click to expand...

I have no idea. I don't have a test load, and I don't want to disassemble my laser to find out. I would assume that it is. I don't know why it wouldn't be linear.
 
There's another difference between the flexdrive and the microboost. The flexdrive is a boost/buck driver and the microboost only does boost. So with the microboost, you have to take care not to use on a diode that needs a voltage lower what the driver input voltage is.
 
Hey guys, about the additional connection to the 471 resistor.. it does nothing. I just use it out of convenience because it's so close by. Look in the photo under the solder blob you'll see a lighter green trace running from that resistor to the exposed pad.. so connecting or not connecting the range jumper blob to that side of the 471 resistor does not have an effect.. merely convenience.

Oh, and yes the current change is nearly linear, unlike the FlexDrive V5 which ramps up faster at the end of the high ranges.
 
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drlava said:
...

Oh, and yes the current change is nearly linear, unlike the FlexDrive V5 which ramps up faster at the end of the high ranges.
Click to expand...

Thanks for the info. Is that because you used a non-linear pot in the flexdrive?
 
Alright, once I find some thermal epoxy I can tell you how much current boost I get when I change from the highest setting listed in the datasheet and the extra resistor (to see if I get 1200 or 1100mA). 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?
 
Hey DrLava. Just wanted to get your official word on the matter.

If the range is 540 - 1000, will those be the high/low when turning the pot either way ?

I mean approximately, I don't mind if its off a little, like +/- 50mA.

So for example, can I assume :

Total current = 540mA + (460/270)X, with:

-460 being the remaining current from range (1000 - 540)
-270 being the total amount, in degrees, that the pot can turn stop to stop
-X being the degrees the pot is turned from counterclockwise

Which would give approx (with the pot starting from full counter clockwise)

Each 90 degree turn giving approx 153mA plus the 540mA initial value

0 degrees - 540mA
90 degrees - 693mA
180 degrees - 846mA
270 degrees - 1000mA

Approximations are correct ?
 
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