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V5--Pot--LD? Possible?

LuxorLasers147

LuxorLasers147

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I´m building a labstyle 445 laser but it uses the flex drive v5 (set to 1.5A) to have good efficiency, but this means i cant ajust the output once it´s finished. So it would be great to find a way to do just that with no prob.

So my question is : Can you wire a pot between the driver v5 and LD?

I think it´s doable since it doesnt cut the flow of current. The only problem i see is overheating the pot, especially at 1.5A.

What you guys think?
 
Last edited:





lasersbee

lasersbee

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No you can't...
A pot is a mechanical device with a Wiper that slides across
a resistive surface...

If that wiper (for a small fraction of a second) should not
make contact with the resistive surface... The driver will
see a no load condition and increase the voltage to maxium
to compensate for the Low resistance load and charge the
output capacitors to max Voltage..

When that (small fraction of a second) no resistance error is
corrected the full potential (voltage) across the output cap
is placed across the Laser Diode and it will surely BLOW....

Do some research and reading on trhe Forum and you will
find the answers to a lot of basic questions like this...


Jerry
 
Cyparagon

Cyparagon

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^^That's why you connect them like this:

pot_schematic.gif


The problem isn't with the wiper, it's the fact that a laser driver is a constant current source. And since lasers are current driven, increasing the resistance in series will only raise the voltage seen by the driver. Power output remains the same.
 
lasersbee

lasersbee

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In my experience...people who ask basic questions like
that... 90% of the time will eave one end of the pot floating...
But yes... that would solve my scenario...:beer:


Jerry
 
LuxorLasers147

LuxorLasers147

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Joined
Aug 14, 2010
Messages
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lasersbee said:
No you can't...
A pot is a mechanical device with a Wiper that slides across
a resistive surface...

If that wiper (for a small fraction of a second) should not
make contact with the resistive surface... The driver will
see a no load condition and increase the voltage to maxium
to compensate for the Low resistance load and charge the
output capacitors to max Voltage..

When that (small fraction of a second) no resistance error is
corrected the full potential (voltage) across the output cap
is placed across the Laser Diode and it will surely BLOW....

Do some research and reading on trhe Forum and you will
find the answers to a lot of basic questions like this...


Jerry
Click to expand...
Oh i see what you mean, the "irony of caps", they help you live but they can also kill ya xD
What about this set up? Batts + pot + V5 + LD

I know i should search a bit but belive me i dont have time and patience right know >.<
 
LuxorLasers147

LuxorLasers147

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Joined
Aug 14, 2010
Messages
177
Points
18
Cyparagon said:
^^That's why you connect them like this:

pot_schematic.gif


The problem isn't with the wiper, it's the fact that a laser driver is a constant current source. And since lasers are current driven, increasing the resistance in series will only raise the voltage seen by the driver. Power output remains the same.
Click to expand...
ty for info!
 
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