Driver out of a d1v2 sst20 DR.
What’s stopping it from overdriving the deep red sst20 that it came hooked up to? Just R3? 240k?
Linear driver for red LED? That would waste so much energy since it had to drop voltage from 4v down to 2.2v or something. I buck driver makes much more sense.
It’s a linear constant current driver, the resistance of the mosfet (Q2) varies to keep the current constant.
it’s set at 3.8A.
Vsense is set by R3=240k
Vsense= 2.8×3.3/(240+3.3)=38mV
Rsense=R10=10mR
Iout = 38/10=3.8A
3 Thanks
Thanks! Perfect.
That’s higher power than I would’ve thought eh? For the deep red? That’s what I get at the tailcap with the w1. Same driver setup? I guess so eh. Wouldn’t have called that
I don’t suppose you (or anybody else) would know the best way to accommodate this driver for an sft40? Or an emitter along those lines. Higher power.
Would you change just R3, would you just stack on R10, or both?
I believe Hank does both. I think he has R3 at 180Kohm in the 5A linear with the same 10mohm R10, and I believe he changes or parallels the current sense in the drivers >5A. Don’t know what he does with R3 in those. So I assume that’s the proper way to do it… But it’d be alot easier to just stack on R10 lol
Btw, does it look like that 2nd FET is being used with the no-fet firmware?