Convoy's 17mm / 22mm driver for SST-40 sense resistor mod feedback :-/

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Barkuti
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Convoy's 17mm / 22mm driver for SST-40 sense resistor mod feedback :-/

This driver: https://www.aliexpress.com/item/17mm-22mm-driver-for-luminus-sst40-LED/32989372464.html

Made a bet with them and bought some. Since theoretically they can deliver up to 8A to the emitter without brakes, I modified one ∅17mm unit by swapping its R005 sense resistor with a stack of 2x R020s. An unmodified ∅22mm driver I have installed in a C8S does just a smidgen above 7.6A, while the modded unit measures ≈3.875A max (DC power supply amperimeter readings). So it works, but something is not there. The unmodified driver blinks 36 times when ramping, the modded one also does 36 but only the later 30 can be seen, there's a brief pause in the darkness when it starts from minimum. Also, the special “3rd” mode selection blinks remain Sick unseen and the 1% mode doesn't works (unseen too).

I do not have a good explanation as to why this happens, it shouldn't happen as V = I × R and hence the sense voltage remains Question constant. The special mode selection blinks are faint, they may be using the 5/36 or 6/36 ramping brightness level and this tells me if I stack more sense resistors they will eventually become viewable. But what about the 1% brightness level? Facepalm

Explanations?

 

Cheers Smile 

Edited by: Barkuti on 06/12/2019 - 10:07
BlueSwordM
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Wait, why didn’t you use a pure linear driver then?

https://www.aliexpress.com/store/product/17mm-Driver-for-SST40-4-modes-0...

That would make modifications much easier.

My very own high current Beryllium Copper springs Gen 3:
http://budgetlightforum.com/node/67401
Liitokala Aliexpress Stores Battery Fraud: http://budgetlightforum.com/node/60547

Barkuti
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That other SST-40 5A max driver with sequential mode change is just another story. Did someone try sense resistor adjustments with that one? The lowest mode could also stop working with it, even if just a little reduction shouldn't be a problem.

Anyway, what matters here is why in @#$% does this happen with this 8A weird firmware units. Sure there is a reason somewhere. I have another ∅17mm weird firmware unit waiting to be tested with less than 10mΩ of sense resistor, so we'll see. 

 

Smile