Why don’t we start simple and leave 3 coin setup and threaded modules for later!
This. I’m just thinking a high power remote momentary switch. Because most remote switches have such tiny wires, it kinda kills the amps the driver can get for maximum power!
Amen!
Attempting higher current also kills cheap switches. This device solves both problems at once. Simplicity usually = reliability and can be amended later once the concept becomes proven. One step at a time, let’s start simple (and as cheap as possible without risking reliability).
Phil
I had before this came about, simply because I’m an EE dropout and didn’t get far enough for the whole of this to make sense to me lol.
What interested me was the multi-modes available on some of the side switched lights. And by multi-modes I don’t mean simply multiple levels, but the ability to long press for momentary or double tap for on, or something similar.
The problem I ran I ran into was the drivers I found separately didnt have the modes I wanted, and were all too large to be useful in that application.
Hopefully something materializes out of this that will work for multiple applications.
ETA: On that note, maybe something is already available that will work in a similar way as described above and I’ve missed it. What the smallest BLF driver that is programmable? 17mm? Is one of those be designed in a way that requires constant battery input and the PIC is operated by a separate channel? If so, I’d imagine there is a way to shoehorn one into a light and have the switched signal come from a tape switch. Then a custom program could be made with the operation similar to what I described above.
If this it too far OT guys let me know, I could always start a separate thread it this to keep from cluttering this thread?
Thanks
Smallest attiny FET driver is 10mm.
Mosfet remote tail cap switch.
Been there, done that and have the T-Shirt.
I made these awhile back and they were for positive ground as PT54 as all other PT emitters. My tailcap either switch or tape activated were powered by a CR2016 coin cell. My PT120 thd fet was installed inside of the heatsink so I could access the negative pole and the coin cell was not needed. You can search CPF for a switch called a “FETtie”. I too am electronicly challenged but was able to reverse engineer his design into a spring loaded switch circuit board with a PETE plastic housing and a hot glue gun. For conventional negative ground switch a reverse mosfet from what I used maybe needed. More info is in a post on exact mosfet used.
Mentioned here
Sorry, should have been more clear. What’s the smallest driver with constant battery input that is switched by momentary?
I thought the 10mm was a standard, not side switched?
Thanks
The mtn10DD is available in that arrangement. E-switched, powered are all times(unless a lock out is used). I’m not saying it’s the best option or a budget one but it is what you asked for. Personally I think a driver adds more complexity than is called for, a simple fet with enough voltage to fully open the gate and a pull down to shut it off quickly. Whether in the form of super caps or coin cells should probably be determined by size and space available.
Here’s an lir2032 with tabs. It has a higher nominal voltage than one 3V cell or two 1.5V cells so it should do a better job of holding the gate of the FET open than a cell(s) with a nominal 2.5V which is right on the borderline of the dreaded linear region for even good FETs.
Thanks for the reply.
I agree on all points, just thought a driver like that might work for me in the meantime until something materializes here.
Thanks
Until a few get built its probably going to be a DIY board and parts list at best. At that point maybe someone can enlist Simon at Convoy to see about an oem replacement tail cap. For now you can probably just scavenge a switch board and air wire the fet, cell tabs, and switch wires. You’d have to do that with a driver anyway.
I’d be extremely interested in an oshpark board. Excited.
[quote=Sharpie]
I’m getting a bit lost here. Are you saying that when in use, should the cell/cap drop below threshold power the light would go off?
So if one tests the light for function momentarily, would that charge the cap? Just trying to get my head wrapped around this after a long intense day at work 
Phil
R.E. lighted tail cap: Anything located in the tail cap is located after the led in the circuit so there isn’t any voltage left to power it when the light is on. With the light off a trickle of current flows through the leak resistor but the main voltage drop occurs across the led(s) in the tail. Led’s, mcu, or gate of an fet there is only voltage available when the light is off unless another source like a cell or super cap is added. A light with a cell carrier might be modded to bring voltage to the tail cap but that means either a bigger light or low capacity cells(3 X 10440).
Only mentioned the lighted tail cap to illustrate the voltage issue. I suggested a rechargeable cell because of its higher voltage and the solder tabs which eliminate the need for a holder which would occupy space and need to be accessible. In any case, I’m just contributing suggestions not pushing for any particular design.
In post #34, Sharpie lays it out pretty clearly what to do for a momentary setup.
I’m more interested in what’s needed to make a latching circuit(if that’s the right term).
Ie; replace the clicky switch inside the tailcap with small e-switch, & the CAP/coin cell FET circuit described above, but have the FET switched & held by each ‘click’ of the e-switch.
What would need to be added to that circuit, or changed, for this to happen?
My guess for this to happen would to build a flip flop circuit. It would add more components, but I think that will work for that application.
I’m seeing both sides of this coin here. Replacing a mechanical PB with an electronic one controlling a FET will be awesome for radical amps; and from looking at the amazing Lighted Tailcap “project” it appears there’s plenty of room for a flip-flop. (BTW, in case anyone’s interested, old computer keyboards are an excellent source of tiny momentary switches…)
OTOH, I’ve had a rifle light mounted since before Cree made LEDs; in which the remote switch would become a fusible link if I tried it on even an entry-level C8…
An extra battery bothers me, though. I’d like to put in a vote for the capacitor, since I would never use a rifle light for general illumination & almost never leave it on for more than a few seconds.
If the driver can provide the power and a small cap can keep the FET turned on for, say 15 seconds or so, that would be pretty awesome, in my world.
(Posting this just to subscribe. Back to lurking…)
EDIT: with this foundation, you could replace the switch with one of those “touch-switch” circuits. Then to turn on the torch, just pick it up! Oooooo!
Thanks, Sharpie.
I’m pretty keen to get one of these happening. 
I was thinking there are a lot of ways a pressure switch can get pressed accidentally…
And if you’re making enough light to be useful, you’d be making enough heat to be dangerous. In the case, across your shoulder in daylight, etc. Sometimes we might forget to unscrew the tailcap…
It seems to me, a for a targeting light, straight DD with a recoil-proof spring & braid at B+ to the LED, then a MOSFET tailcap Gated by the pressure switch, would be a great combination, and if you sized your supercap to discharge w/in a half-minute or less (maybe even a lot less, for safety and a much smaller cap), wouldn’t that be useful, at a minimum complexity level & BOM? Obviously with no driver to leak current, you’d need a wee bleeder resistor to charge the supercap.
I went looking for a MOSFET. Has anyone ever heard of or tried one of these 360μΩ, 5 V/60 A N-Channel MOSFET ? It’s spendy, but for a single-cell light (max VDSS is only 5V) the 60A limit looks intriguing, and it supposedly turns on in 1.2V so it doesn’t eat much.
It’s cute as a button & would leave lots of room for other goodies.
I’d appreciate some opinions, since this almost seems “too good to be true”…
Am I off base here, or does that seem like a useful MOSFET (if priced somewhat ‘regally’…)?