Review and disassembly: Sofirn SF36

SF36: Non constant Current output

Great review, does the battery tube interchange between the sofirn and the thorefire?

Exactly. No constant output at all. FET, PWM 21 kHz.

Replace my sf36 then, I want constant output when voltage > 3.7 V :wink:

You SP-series have stabilisation when voltage > 3.7V, but SF-series (SF36, SF31)- NO.

No, it doesn’t.
It’s very different design on the part conecting the head, you can see in my VG10S review.

Good review.
_8502 sot23-6 on board :slight_smile:
You can safely use non-protected batteries. Protection already exists in the driver._

That’s good to know.

I got mine and checked it.
Unfortunately this does not work.
The flashlight starts flashing when the voltage drops below 2.7V
edit: power off after 2 min

Some of my photos in the album Светодиодные фонари и световые приборы. Всё о светотехнике. - Альбом MSS: Sofirn SF36

I need to double-check with my SF36 but I think the light turned off when testing with an unprotected battery.

When the LVP starts blinking you should change battery ASAP anyway.

EDIT
So I did :

at 2.78V the LVP blinking started, then after ~1min the light turned off.

But if I turn it on again, it will do another blinking cycle, then turn off after ~1min again. Etc, etc.

Maybe you got a faulty driver.

About 2.7 is turn off for mine too.
Can’t remember exact number but that’s close enough.

Has anyone compared the drivers for sale with the drivers in the flashlights?
I’d like to know which ones are used. They have three drivers for sale, identified with a flashlight model number:

https://www.aliexpress.com/wholesale?catId=0&initiative_id=SB_20170728122116&SearchText=sofirn+driver

(C8S, VG15/SF31, and C34)

I can’t tell which have low voltage protection, or whether any of those are constant current drivers (I don’t own any of those flashlights)

On the Fonarevka.ru, they tell me that it does not turn off immediately. It is necessary to wait some time, after it starts to flash. But I can check it only on Monday.

At mine - usual direct drive. Without an inductor. From the laboratory power supply at 4.2V, the current on the LED is 4.6A (Hi mode)

The flashlight starts flashing when the voltage drops below 2.7V
and power off after 2 min :+1:

What I see is none of that drivers from Aliexpress is not in SF36.

Wondering if a clamp meter on a loop of negative lead from the mcpcb would clearly show the emitter amperage as a cell loses power? That would easily clear up direct drive or regulated questions.

XXX measured 3.2A at the tail, which is not direct drive even if only limited by the R091 sense resistor. Higher amps would be easily obtained through a change in the resistor.

Tracy confirmed, above, that this is not intended to be a constant current driver. So it’s all probably a moot point… just wondering why we get a 3.20A reading on a cell and a 4.6A reading from a power supply?

I think I actually like the SF36 better than the VG10 series due to the knurling… :wink:

Soon I will build my power supply with DPH3205 so I can provide info on current with it.

I recently acquired a power supply, for a specific purpose. After this purpose I will be able to use this lab style power supply on my bench, but since I know virtually nothing about these I find myself at a loss as to why I’d use it over just using a cell like I’ve always done in the past. This is why I ask. To what point is the power supply used? The readings one gets are not valid as we use a flashlight with cells, which sag and lose power.

I needed a supply for an 18V emitter that would use up to 1.2A current. So I chose a 30V 5A unit. It’s working great for this project, so far, remains to be seen what I do with it afterwards…. a lot to learn still. :slight_smile:

You are correct. Cells drop voltage at high current fast.

Especially at an 8.5C discharge rate. :smiley:

Well I don’t have light like that…