12A 7135 Based SRK Replacement Driver

The Qlite has routing under the chips, in the dozens (100?) that I’ve used, it’s never been an issue and so far I’ve run em up to 4 high and over 6A. Lucky maybe, don’t know.

Great stuff. I’ll keep on eye on this and see how it all pans out. I already have some SRK drivers on the way so I don’t need them just yet.

Thanks

Every cheap 7135 board I’ve seen has the output trace crossing under the chips. It doesn’t mean it’s good design but does seem to work. Breaking up the output into groups could be done just by cutting the output trace in a few places and soldering an led- wire to one of the chips in each isolated group. For a high voltage Zener mod it would be better maybe to have the entire bottom of the chip available for ground trace soldering but maybe not as important for normal 4.2V usage. The natives have been getting restless waiting for an SRK board and this is a sort of stop gap measure. I like that Mattaus is willing to put things out there knowing that his first effort can be improved on and that Texaspyro takes the time to make suggestions. We all learn from them and gain by their efforts.

Sorry RBD. I failed on most of that last line. :_(

Okay, so maybe “all learn” is a bit much but we still get new designs we can use whether we understand them or not.

Comfychair wrote:

I'm pretty sure there will soon be a different version using a single direct-drive FET,in case there are others who are a bit tired of the 7135s.

(this one works great, Vishay SUD70N02-03P)

Very much looking forward to that. Ordered some and I'm off to your thread to figure out how to wire them into this board.
On TexasPyro's point above about contact pads for cells and the battery tube. If there is a problem with this design, I imagine one could reflow some copper sheet cut to the appropriate size over the positive contact ring.

I guess part of the accidental 'charm' of this (or any 7135 based driver) is the relative ease of which the boards can be 'hacked' up. Seriously - I've seen some of the boards people have created, even some I've made, and they look like they've been put through a meat grinder. And yet they still function. Boards with chips stacked 4 or 5 high (sometimes more). Traces ripped up with jumper wires running left and right. Extra components tacked on. AMC chips being driven above and beyond their factory rating. Master/slave setups. The list goes on.

All this board will really ever be is a NANJG driver sized to natively fit a very popular light. If you're concerned about a large group of AMC chips running LEDs parallel then just go to town on the board. Leave a few chips off and stack them else where if you need room. Swap out the MCU for another. Zener mod it. Hell; you could just use it as a simple contact board for an all together completely different driver for all it matters lol.

Use it how you see fit and do what people around here do best - make up for its shortcomings by ghetto engineering the crap out of it.

- Matt

The problem is not with the contact ring, it is with those pads/holes for wires at the center of the board. The positive contact for the cells can touch them… even if there are no wires protruding. The center part of the driver board really needs to be empty. If I remember correctly, anything within around 0.2” of the board’s center is a risk for shorting with some cells.

So add a copper ring.

Extra bonus, it'll work with unmodified flat top cells, no solder blobs needed.

I think the point is that reflowing a disc on the pos contact ring will shim the B+ contacts and prevent contact with anything in the middle area.

And worse comes to worse… maybe just paint a bit of liquid electrical tape over the inside of the copper + battery ring to protect those thru holes

You read me right Rufusbduck. Thanks for interpreting and clarifying.

Subscribing :)

It's worth a shot if you already have some, but it wasn't tough enough to work with my reflector and probably wouldn't here either. Fujik should work though.

So, I could make 5 or 6 zones and have each one go to one led like this?

Yellow lines is where to cut the traces and numbered areas is where to expose the traces for leads.

It could work for the 5 and 6 led SRK lights. Just stack chips and go.

Interesting...

Once tested, I just might try some.

Thanks

Looks right to me.

WOW..was that a nod from Old-Lumens? :D

How about 32 zones, “angel eyes”.

That's a whole lot of trace cutting "snookums" :D haha

**kissyface** ;)

Sh ts getting deep round here…