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100mw 520 module from techhood/ebay

paul1598419

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I think I will stick to setting the current on drivers as opposed to adjusting them with the diode installed and measuring the output. Just the noise from the pot will kill a diode eventually doing it that way. But, I do hope it doesn't happen to you.
 



RedCowboy

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I think I will stick to setting the current on drivers as opposed to adjusting them with the diode installed and measuring the output. Just the noise from the pot will kill a diode eventually doing it that way. But, I do hope it doesn't happen to you.
If you have proof that the pot of the LDSE500 or ACS1500SE actually introduces damaging noise I would like to see it.

Also what about my bench top power supply ? I have powered many diodes with it while adjusting the pots.

What about the many hobby PS boards I have used and seen people use and adjust on the fly ?

The BB8 has the option of installing a pot for the purpose of adjusting output up to the set limit, is it a danger as well ?
 

paul1598419

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I can't speak to the reliability of your power supplies, but mine use much better pots than can be found on a driver PCB. I also dissembled mine and used a contact cleaner to lube them all against any dirt or debris causing them to become noisy.
 

RedCowboy

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I'm not worried about my benchtop with all it's filtering or the Russian drivers with the non conductive adjuster pots but I don't like the flimsy silver pots, usually I disconnect battery between small adjustments if needed as I do pre set them, but I also check current with an inductive meter unless I solder the diode pins directly to the driver, but with the Russian boards I will continue to take my chances, I feel they are good chances.
 

paul1598419

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As far as the additional pot option on the BB8, that is a limiting option. The current is already at a set maximum, so even if you have a noisy pot there, it shouldn't cause a spike in current like the set pot will.

I have also adjusted the driver current on 532nm modules using an LPM as it is easier than disconnecting the driver and setting it up that way. But, all other drivers I set up prior to adding the diode.
 

RedCowboy

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Yes I know ;)

The 532's can be very fussy so adjusting it on the fly with a non conductive screwdriver is just the most practical way, I set my other silver pot drivers up in advance but the Russian drivers especially the lower current drivers I like to set on the fly, I am not worried about it hurting my laser diode.
 

Cyparagon

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There will be some capacitance downstream of the pot, whether it be a physical component, or an incorporation into the IC's input pin, or outright parasitic. The resistance of the pot itself will form an RC filter with this, which is low pass, and negate most negative effects.

If there's nothing to drive the output high or low when the wiper loses contact for a microsecond, there's nothing to worry about. If you're irrationally worried about it regardless of the facts, add your own capacitance on the input.

There are a few topologies where the input is indeed pulled high or low with no input, but In this case, pot noise is just another groupthink boogeyman.
 







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