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Can I toss my uC controlled flexmod in here?

vk2fro

0
Joined
Nov 30, 2009
Messages
1,304
Points
63
I've been mulling over the design of a flexmod for laser diode testing.

These flexmods are great as you can set them up with a current limit, and then adjust them using the analogue modulation, or bypass it and use the onboard pot.

Or rip that pot off the board and replace it with a digital one, which opens up the avenue of microprocessor control.

Add a metering system, and you can not only load test before connecting, but also monitor live diode current as you test.

Its a works in progress (and waiting my next Flexmod P3 from DrLava), but will make checking out that odd diode, or the one you put aside, and forgot what it was a lot easier.

Features I want:
Voltage and current on screen at all times
Small compact design
Control of gain, bias, and interlock chain from uC
Ramp testing (ramps up the current slowly until you hit a button, good for getting lasing threshold, or with a power meter, a particular mW level)
digital pots with 1024 step resolution
Multi flexmod control - make a labby that goes from deep purple through to white, to deep red in one box!
Line control - pick a nm and the lasers are set to it (you'll need to set this up for your particular diode set)
kill switch (emergency stop, closed loop {aka interlock})

CHEAP! (aka basic stamp or PIC)

Any other ideas post them here :)
 





Benm

0
Joined
Aug 16, 2007
Messages
7,896
Points
113
It should be doable. I don't know if the flexmod is particularly suited for this application, but any driver the outputs a current based on an input voltage would, in theory, be usable. You can use the digital pots, or a DAC integrated in the uC, or even an external DAC.

To read back the current and voltage you will need 2 ADC's, and the one for the current could be particularly tricky since it has to sense rather small voltages. There are many PICs (and AVRs too, i suppose) with built-in adc and dac functions, its probably best to test if those suffice.
 




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