BLF17DD Info Thread - Reference

Flashlight Modding and DIY Parts
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This is an attempt to keep tech ref info on the BLF17DD driver(s) together in one spot, hopefully easier to reference this way.

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Note: Post #124 is a great write-up by RMM on voltage divider calculations

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As of July 12th, 2014:

The new improved 17mm FET based driver here: OSHPark BLF17DD V1.0

It's matching parts list: DigiKey shared cart- BLF-17DD & BLF-20DD Qty 1 (includes a working MOSFET now!)

Post #1045 here in the big OSHPark thread from comfychair has pretty good details on this upgrade. Basically, it's an alternate solution to using the 130 ohm resistor to reduce a voltage spike flatten the peak. Actually this new CAP method works so well, it opens up the possibility of using other FET's.

Post #1077 here in the big OSHPark thread from comfychair explains where/how to do the zener mod on this board, as well as explain where/how to do the off time memory CAP mod.

(Pictures to be added here. Not ordered yet - hope the design is settling down for now...)

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As of June 15th, 2014: (this is obsoleted now, but still applied for those with the old rev boards)

There are now two version of the BLF17DD: standard and zener diode mod version:

PCB link standard: OSH Park BLF17DD Rev 4 (link not working now - it's been removed to allow no more buys)

PCB link for Zener diode version: OSH Park BLF17DD Zener Rev 2

You don't need the zener version to do the zener mod - it can be done to the standard BLF17DD as well, just little more difficult.

Notes:

Sample View:

This is a Rev 2 or 3 populated, first top (inside) and second bottom (spring side) showing the parts positioned correctly. Note: I'm using a 100 ohm resistor in position R3, but a 130 ohm should be used for R3 -- it's a better value (100 ohm is borderline). Here:

Detail view of the diode positioning:

Sample Assembly:

This is the solder paste I use:

This shows the application of it:

This is the placed parts on to the wet solder paste:

I use a hobbyist hot air gun which is low air speed, so pretty safe to do reflows. Takes like 30 secs to 1 minute but works well. After the reflow:

Again, this is showing parts position for the reflow. This sample is for a zener mod. Note the 200 ohm resistor (2000) is used in place of the diode:

This is after the reflow, and shows the Zener Diode soldered onto the side of the cap:

Detailed view of the diode. The marked end of the diode is on the opposite side from ground:

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I’ve got a few of these to build, thanks for posting detail pictures. I would have had to scroll through a few posts to figure out what goes where and zoom in on some pictures.

This is going to help me a lot. Thanks, and thanks to all who worked on these and figured them out then shared it.

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Hoping it will help. I've had to do the same thing - lots of searching. I'll try to cram as much useful info in the OP as I can... I'm still updating it.

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Thanks Tom. This is what I needed a week ago. A picture is worth a thousand words.

I might add, these components are small. To check your Zener/resistor installation with a DMM, one end of the Zener should have continuity to ground, and the end with the “D” should have continuity to the 200 ohm resistor (2000) at the end facing the outer edge of the driver board.

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+1, thanks Tom, for this thread, for some people, like me, it helps because I'm not that much into electronics, so what is obvious for the guru's is not always obvious to me. And I do like to use this driver, a lot.

One question, the non-zener diode version, those are, even apart from the FET, not exactly the components that can be recovered from a 105C (I miss the diode labeled S1), what is the difference of this driver with comfy's FET-modded 105C that started the developement of this board?

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Only the difference should be the 100 ohm resistor that's been added. Don't think anyone knows for sure why it was needed on these BLF boards, but in some case (most?) it prevents flaky mode changing I believe. The diode should be identical to the one from the Nanjg/Qlite boards. It's an SOD-323 (digikey listing and datasheet - ZLLS410.pdf) but labeled 41.

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nice!

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Thanks for breaking this out into a separate discussion. Is anyone else getting and empty digikey cart with the current link?

Edit: comfychair's link works. Thanks comfychair!

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Great thread Tom. TY!

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http://www.digikey.com/classic/Ordering/AddPart.aspx?WT.z_cid=Shared_Cart is not the link for the shared cart, it’s the URL after you’ve clicked the shared link and parts have been added, you need to use the shortened link from the pop-up box. Or right-click/copy the link as given in the Oshpark projects thread.

Parts list for 17 & 20DD, for 10 drivers: shared cart- 17&20DD, qty 10

Save yourself some trouble and order the resistors in batches of 100 at a time, it's only $1.22/100. The 19.1k can be used for both the voltage divider and the gate pulldown (R4). There's no reason not to use R4, anything from 10k to 20k is too high to have any negative effect on the signal to the FET, but will make sure there's no residual charge left at the gate during the time when the MCU has commanded the FET 'off'.

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In response to your question on the R3 value, I believe 100ohm is about the bare minimum and 150 is to high. Your not noticing any ill effects with that one, skipping modes or not switching when it should? Have you tested it with both physical clickies and momentary button setup’s?

I’d be more than happy to drop a few 130ohm 0805’s in a regular mail envelope for you, I have a strip of 1000. PM me your address if I can hook you up.

Your soldering is extremely clean. I use an iron so I get a good amount of extra solder everywhere when I do it, yours look very professional!

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Awesome Tom… now I dont have to search further, excellent details too :beer: :beer:

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The cart link in the Oshpark thread seems to work.

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Sorry - been out all day - wifey and I had a car accident this eve - she was driving... No one hurt, but more like a strong fender bender.

I do have qty 100 130 ohm resistor on order from yesterday, from California, so hoping later half of this week, so I'll be set. Thanks for the offer though Wink.

Haven't noticed any issues - only used/tested in a conventional reverse clickie. Actually I should have cleaned the board with iso. alcohol, but didn't. The hot air reflow method is great! Love it! The heat gun I use is cheap, like under $10-$20 maybe? It's a "StampAbilities Heat Embossing Gun". This is one example: ebay-stampabilities-heat-embossing-gun. A friend had several he uses for small PC board projects in hobby rocketry and other side-work projects, and he gave me one.

I gotta fix that link. Thanx comfy!! Just tried to copy the link RufusbDuck had... HHmm...

Oops, updated again from comfy (includes 130 ohm resistors) I updated the DigiKey parts list link in the OP - please try again, thanx!!

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How low do you adjust the air on your hot air reflow? Doesn’t it blow all the components off the board?

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I adjust the distance I hold it from the board - this gun has no adjustments at all. I was leary of this, but why my friend loves using these things is it's pretty low speed on the air, unlike conventional hot air guns. In the few boards I did, it happened only once on the diode which is the smallest high sitting SMD, but only happened because I did not have enough solder on the pad. All I did was add solder paste, push it in good, then it worked fine.

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I guess I should experiment with the different sized nozzles. I’ve only ever done one component at at time, and hold it in place with tweezers. With full air, it’s soldered down in seconds.

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Turn the fan down and the heat up. I use the fan on around #4 and the temp at 310-330, I don't know what the actual temp is but nothing melts but the solder and nothing gets blown off.

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Are you still using the YIHUA like mine?

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Yes, 858D.