BLF15.17DD Info Thread - Reference

Flashlight Modding and DIY Parts
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I took the redesigned BLF15DD, then upped the diameter to 17mm

https://oshpark.com/shared_projects/jRpEIU7P

It’s a single sided driver, so it will fit most standard 17mm driver slots but allow for a bit more current for higher powered “daily drivers” than that POWERHOUSE TO-252 FET on the standard 17mm.

Digikey shopping cart , includes irlm 2502 FET (apparently there is a “better” FET out now (thanks comfychair), with almost 1/2 the Rds On resistance which means MORE power thru the FET) AO3400A

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3D Render
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Corrected to put the SOD-323 diode back on

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To think that a few months ago I fitted one of those huge Vishay FET's onto a Tiny10 and modded one of the smallest AAA lights out there with it (UF-LZZ6) .

The choice of drivers is getter better and better :-) , thanks for this one, if I can get hold of that even better small FET that comfy came up with, this is the driver to update a few of my small edc-lights with.

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I will correct the diode when I get home from work…it will be up around 7am CST

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Just found another possibly compatible FET with better specs: http://www.digikey.com/product-detail/en/DMN2020LSN-7/DMN2020LSN-7DICT-ND/2182565

That AO3400 was one I tracked down as an exact replacement for the stock TR-J18 driver. I have both parts ordered to test.

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I was just about to recommend the DMN2020LSN. Not only it has the best rdson with lowest vgs, it also integrates esd-protection, which is a plus especially when the components will be hand soldered.

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updated and ready to go

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Low Vgs isn't all that critical in these drivers, we're throwing battery voltage (minus a tiny drop from the protection diode) onto the gate, and they work well. Lower Rds(on) is always a plus though.

It's hard to translate the datasheet-speak into what these will do in the real world, I don't think any of these parts were ever intended for a circuit like this.

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The cart still has the 130ohm gate resistor but lacks the OTC. Is that value the same as C1?

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Nope. 10uF for C1, 1uF for OTC.

http://www.digikey.com/product-detail/en/C0805C105J4RACTU/399-8001-1-ND/3471724

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And much cheaper here, but won't last forever. 10v instead of 16v, but that doesn't matter for this. http://www.ebay.com/itm/181283883536

(check out the Digikey pricing for 100 of the same parts as the $4.99 ebay ones: http://www.digikey.com/product-detail/en/C0805C105J8RACTU/399-8002-1-ND/3471725 :O )

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If you end up doing Zener mods it might be handy to have the extra overhead. I loaded the cart with a 1 microfarad 25V version that’s only $.07 each for 10. Same Samsung brand but I wonder if it makes sense to go with another brand so they look different and are easier to tell apart. Btw, price for 100 is only $3.27.

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Still doesn't matter. 10v is fine. If there's more than 10 volts at MCU pin 2 something has gone catastrophically wrong.

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Mine’s still cheaper than yours. :stuck_out_tongue:

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I don't see anything from Samsung in the list with the right specs (1uF 0805 5% X7R), of any voltage.

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How did you determine the exact value and precision needed? I couldn’t locate that anywhere in your scope thread so I put a 1 microfarad 0805 10% cap in the cart.

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That was what they decided on in the STAR FW thread. Jonny tried several different ones when working on the off-time version and that's what he settled on.

Zener or no zener, there's no way for anything higher than Vcc to get to the off-time capacitor. For that to happen you'd have to be using 3 or more cells and then forget to install the zener, and at that point what happens to the capacitor is irrelevant because the MCU will have already died.

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Mine should be in tomorrow :slight_smile:

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Is the diode different that the diode on the old 17’s? Its silkscreen outline and pad spacing looks larger. Brian will those diodes I sent you (marked S4) fit these or will I need new ones? It looks like it’s the size for the Zener diodes we use.

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I used a SOD-123 diode from Mattaus’s lbr I got from him

Do you think it’s not the right part…will check when I get home

Hopefully it’s not too big…the SOD-323 might be smaller

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I changed it back to the original SOD-323, it is quite smaller but the pads are still quite close…should I go ahead and update to the smaller one?

I can say this, if this is the same diode that were on the old BLF drivers, the pads were very close together and sometimes the diodes wouldn’t stick down properly

The version that is up now is the SOD-123, initial release was SOD-323. Here is the pads next to each other

First 3 are SOD-123, the last small one is the SOD323…very small and that is the ones that I had a hard time getting the diode to stick down with


The SOD-123 from Mattaus (#3) looks like the right one and the one most universal

That is the one that is up right now on OSHPark

If you notice your special build the BLF15DD piston has the SOD-323 on it…when you put the resistors on it did they fit perfectly or seem to almost float on the solder on the pads?

You have built more of these than I have…do the diodes fit best on the 123 or 323 pads?

Ok, I just broke out all my boards I had

The schottky diodes you sent me are those the ones in the purchase list for the BLF drivers on the OSHPark page? If so then the SOD323 fits perfectly, my original builds i had a bigger diode…that might be the problem

If those are the right diodes then I need to set the size back…but the ones you set me should fit but will be on the outskirts of the pads

Should I fix it?

Ah crap…the digikey shopping list shows SOD-323…fixing back to the original build!

Luckily Mattaus reviewed and corrected all the other builds…the only one that uses that large footprint is the TexasPyro, but if you look the pads are really big so the SOD-323 will fit anyway :slight_smile: