Sofirn C8S 5 modes circuit board anti-reverse led driver

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Barkuti
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Sofirn C8S 5 modes circuit board anti-reverse led driver

 

Got one from Sofirn. I had ordered a C8S host but received this: opened dispute and asked for a reimbursement minus half the cost of the driver (€8.16). Got it.

Any info? Hope the sense voltage is low. 

 

Cheers Party

Edited by: Barkuti on 06/29/2018 - 20:17
eas
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I’m not 100% sure, but I think that is the driver from the Thorfire C8s, if that helps with tracking down more details.

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Redlyne22
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I think the sofirn C8f and C8 have fet drivers, what you posted looks to be a buck driver.

Key words” I think “ so I’m not sure, but at the same time somewhat certain.

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Barkuti
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That is a buck driver meant for the C8S series, with 20+mm driver boot size.

Uses an R082 for 3A max driving current, this means a whopping 240-250mV sense voltage and ≈738mW of dissipated power at the sense resistor. Barely moddable for increased output current before power loss at the sense resistor becomes a problem, imho. And not really well suited for 1S input.

Could be a nice driver for some inexpensive headlamp mod, I believe.

 

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Redlyne22
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Nice, ya, you know more then me. So let me ask you:-) What do you specificly mean by moddable?

I know that buck drivers have to burn off extra power by turning it into heat. So this driver would be somewhat pointless for a 1S. And better suited for 2S and or 2P?

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Barkuti
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Redlyne22 wrote:
Nice, ya, you know more then me. So let me ask you:-) What do you specificly mean by moddable?

I know that buck drivers have to burn off extra power by turning it into heat. …

Buck, boost, and any sort of driver which measures voltage drop across a sense resistor to regulate output currents can be easily modified for a different current by changing the value of the sense resistor. Since Rsense = Vsense / I, Vsense = Rsense × I. However, since dissipated power at the sense resistor Psense = Vsense × I = Rsense × I², it quickly becomes clear only drivers which use small sensing voltages can be used for a higher output power without straight cooking it.

 

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eas
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Redlyne22 wrote:
I know that buck drivers have to burn off extra power by turning it into heat. So this driver would be somewhat pointless for a 1S. And better suited for 2S and or 2P?

Buck drivers do not have to burn off extra power by turning it into heat. Buck drivers convert voltage to current. So, 6v in at 2A becomes 4A at 3v (ignoring the impact of inefficiency).

Linear drivers/regulators do burn off excess power/voltage as heat.

Buck drivers are best suited for situations where supply voltage is significantly higher than the emitters forward voltage. So, yes to a 2s (or 3s) light, no to a 2P light, unless it has a very low Vf emitter. This driver was probably intended to be used by lights that could take 1× 18650 or two cr132 in series.

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Barkuti
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Thanks eas, forgot to explain that.

By the way, one of the main hurdles with current buck and boost drivers is the piece of sh1t (sorry! Big Smile ) lots of them are. Look at that C8S one: the sense resistor is in series with the emitter (as it should be) but its humongous! The emitter drops about 3.2V let's say, and it's sensing resistor adds additional 246mV. This is more than 7% output power being burned at the driver sense resistor. Ridiculous. Facepalm

Current flow needs to be inferred from the switcher MOSFET resistance, I believe. Lesser part count, lesser heat to deal with, higher efficiency and chance to increase output power a lot.

 

Cheers Party

Originally posted on Sun, 07/01/2018 - 04:30. Edited for typo fixup.

Redlyne22
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Nice, thank you guys. Possible sticky thread (if it doesnt exists allready)

Ok, I got one for you guys!! I just received a mystery driver from aliexpress. In The listing, seller claims it is specifily for a SST-40.
Here is the Info from the seller.

(Copied pasted)
Input Voltage: DC3.7-4.2V

Output Voltage: DC3.2-3.6V

Output Current: 2.4-2.5A

Diameter: 16mm

Modes: High-middle-low- Strobe-SOS

Link pics:
https://photos.app.goo.gl/cFL6gBC3sW9wPWw96

What kindof driver?
Mod-able?
Any weak links/components.
Magic johnson hook shot into a trash bin?

Sometimes being a newb is the best part of a hobbie