SST-90 True CC Driver 10 Amps Hi/Lo Mode

[Fulgeo]

I would be concerned with running 10A through the stock Mag switch. I doubt the driver will draw very much at all when switched off...

I have run 10 amps thru the stock Mag switch in more than one of my more insane hotwire builds. Although it does work I would not trust it for a high duty cycle torch since the life of the stock switch is most probably drastically shortened. The usual trick to get by the limitations of the stock switch is to install a more robust switch of greater capacity or use a good FET. This circuit uses a FET so no worries with the 10 amps. I do trust the stock Mag switch to handle 5 amps. This driver could be used to drive a SST-50, so in that regard what I am trying to find out is could this driver be used to that end. I am not worried too much about the inactive draw of the circuit since it is so miniscule. I just have a preference to have a completely dead circuit in a torch when it is not in use. One thing I do with my mods is to back off the tail cap a few turns when they are not in use. This is easier on the batteries and springs and also acts sort of like a safety.

 

[sector_cleared]

I think you got it right the first time. See sector_cleared's post #167:

"Yes, I can confirm that the MAG switch is only used to cycle through the modes and to program the UI. There is basically no current flow (few µAmps maybe) through the switch."

The blue wire in his wiring diagram is the only link that the Mag switch controls. The Mag switch, mod'ed for momentary operation, toggles the power on that wire to signal the driver UI for mode changes/programming.

The thicker red and brown wires bypass the Mag switch. The red wire goes directly from the driver to Batt+ (typically, this is done by soldering the wire to the small center spring on the bottom of the D Mag switch). The brown wire goes from the driver to GND (typically, this is done by soldering directly to the nut/ground strap connected to the grub screw). The connections are conceptually similar as those used in the JimmyM PhD hotwire regulator, which also bypasses the Mag switch from dealing with high current, using the switch only to signal the regulator board.

For 10A, I'd probably use a minimum of 20 ga. I like safety factors and probably would use the readily available 12 ga, 14 ga, or 16 ga silicone wire from places like The Sandwich Shoppe, Hobby King, Tower Hobbies, etc. Tower has some of the Deans super soft noodle wire, if the stiffness of heavy gauge wire is a concern.

@Justin Case: Its exactly like you discribed it. Thank you for helping out. And the 24 ga was a typo. The driver board is prepared to take up to 14 ga. wire.

sector_cleared,

Is it possible to not bypass the switch with your circuit. Just drive the positive from the top of the Mag switch. In effect connecting the blue control wire with the red positive batt wire on the top of Mag switch tower? I know this would incur the resistance of the Mag switch which is at its limit at about 10 amps, but it would completely isolate the circuit from power when the light would not be in use. If I was going to use this circuit for lower amp projects say 5-6 amps I might consider using it this way if it would work?

If you want to run the driver ON/OFF it could work but I have to verfiy it. But there is no need for that. The shut-down current of the ciruit is >20µAmps which is much less than the self-discharge of a 18650 LiIon. You don't have to worry that it will suck your battery empty.

More detailed:
When not in use, the whole power section of the driver board is shut off. Also the µController. The only thing that is running is a LDO with a super low quiescent current of max. 10µAmps. The µController is set to Wake-on-Interrupt which is triggered by the MAG switch. If you are not so much into electronics: It means it doesn't make a difference in shelf life if you disconnect the driver board from the battery section.

I have a different switch question for sector_cleared. Certain drivers are susceptible to the switch bounce behavior of the Mag-C. Here is a thread with possible solutions by members DonShock and Aircraft800 to explain what I mean. One mod disables the self cleaning feature of the switch while the other increases the tension on the contacts. Darkzero mentions he doesn't do multi-mode mods in a Mag-C unless he's using a TaskLED driver. They don't seem to suffer erratic behavior from the switch design. Also the switch in the Mag-D does not seem to have this problem.

Do you know if your driver will jump modes when used with a Mag-C switch? Obviously this is a defect (design limitation) in the Mag-C switch assembly I'm talking about and not the design of your board. I'm just wondering if you think it will be a problem?

Thanks for the info. I am aware of the chattering of normal switches but I will measure the chattering of the MAG C switch to see if there is a big difference. The driver won't have a problem with that bouncing. It's quite easy to filter it out by software. I am sure George is doing the same with his driver boards.
Just as a side info: Every switch is bouncing. If you are using logic modules you always have to be aware of this behavior. The most simple solution is to use a low pass filter between the input and the switch. But if your low pass filter is designed too small and your switch is causing some serious chattering (MAG C) you are in trouble 😉. The better solution is to filter it in the software. But most cheapo drivers don't have a µController that's why they show erratic behavior.

I hope I didn't miss anything

Cheers

 

[Al Combs]

Thanks for the info. I am aware of the chattering of normal switches but I will measure the chattering of the MAG C switch to see if there is a big difference. The driver won't have a problem with that bouncing. It's quite easy to filter it out by software. I am sure George is doing the same with his driver boards.

Sounds like you've got it all covered. Can't wait...

 

[rayman]

So any news 😉?

rayman

 

[sector_cleared]

Sorry for the long silence.

I got all the parts together yesterday...finally. The allocation problem is driving me crazy. These days it's really difficult to get electronic parts. Some parts have lead times up to 50 weeks :duh2:

Anyways. I am finishing the prototype this week. I will post pics and measurements as soon as possible.

 

[dan1million]

Cant wait to see your results !!

-Dan

 

[netprince]

Has anyone come up with a good way to heatsink one of these? The best thing I could come up with so far is a cut down LED heatsink. While it would have good contact with the tube, I was hoping for a slightly less expensive option...

 

[Al Combs]

Has anyone come up with a good way to heatsink one of these? The best thing I could come up with so far is a cut down LED heatsink. While it would have good contact with the tube, I was hoping for a slightly less expensive option...

How 'bout $1.85 @ Home Depot for a 1" copper coupling? The best part of this is since it will be a double sided board, the tabs of copper you bend over can be of differing heights. 🙂

 

[Nanomiser]

I'm in :thumbsup:

 

[SmurfTacular]

If you haven't already made any, do you have schematics so I can make my own?

Thanks.

 

[Al Combs]

If you haven't already made any, do you have schematics so I can make my own?

Thanks.

Someone already made that request in post #80 of this thread. Since his intention is to sell these boards when completed, giving away the design specs would seriously undermine that effort. Sector_cleared understandably declined in post #82.

 

[ma_sha1]

I'd like to take 2-3, can't wait!

 

[aurum]

Der Wichtel will release his 5A/9A soon ....

 

[SmurfTacular]

Der Wichtel will release his 5A/9A soon ....

This is getting exciting. Battle of the boards!

 

[waddup]

3% 35% 100% and maybe a fast strobe is all any light needs imo.

 

[SmurfTacular]

3% 35% 100% and maybe a fast strobe is all any light needs imo.

As long as you don't have to cycle through modes linearly.

 

[luckybucket]

3% 35% 100% and maybe a fast strobe is all any light needs imo.

I'd like a medium setting that allows me to get at least an hour of runtime at the brightest setting or that allows it to run just below too hot to hold, whichever is less. The problem is I don't know exactly how much power it takes to make the light too hot, but I can calculate an hour of runtime.

 

[Fulgeo]

I'd like a medium setting that allows me to get at least an hour of runtime at the brightest setting or that allows it to run just below too hot to hold, whichever is less. The problem is I don't know exactly how much power it takes to make the light too hot, but I can calculate an hour of runtime.

I have played with the SST-50 and the SST-90. I find about 4.2 amps with a SST-50 is about the most I can drive it and still manage heat in a 1 hour or greater run time in a Mag 3D body. The head does get very hot but you can comfortably hold onto the flashlight at just below the switch position ( were most of us normally hold the flashlight ). This is stand alone runs. The SST-90 generates a little less heat so I have found you can crank it up a bit to 5.0 amps for stand alone runs. If you hold onto a flashlight during extend runs your body becomes a secondary heat sink. You might be able to drive a SST-50 safely at 5.0 amps if you keep it in hand. This is at room temperature mind you. When I go for walks at night when it is cooler out heat is not as much of an issue. I think the perfect 2 mode driver for a SST-90 would be a constant runnable 4.2-5.0 amps low setting and a 9 amp high setting. In a Mag 3D body with a good heatsink you will not be able to run a SST-90 at 9 amps for long. But a brief 5 minute burst of light should be no problem.

 

[Walterk]

I am happy when the Led is driven at full Amps from a wide range of powersources.

All other functions, modes and settings are a bonus.

 

[Kaulquappe]

Hi,

Are there any news about the driver?

Regards from Switzerland

Luca