JM-SST feedback

[JimmyM]

Well, it's been a while since feedback was posted here, so I'll make a couple of announcements regarding further development.
Batch 3 will have an additional component. A MOSFET driver.
In testing some CPFers SSTs that had been returned for repair, etc I figured I'd try employing a proper MOSFET driver between the comparator and the FET. It worked fantastically! It swept smoothly from <50% up to 100% under heavy load with none of the previous twitchiness seen in some SSTs under heavy load. So I returned their JM-SSTs with the MOSFET driver installed.
Sooo.
1) I'll be decreasing the resistor values used in the soft start / Duty cycle setting circuit.
2) Increase the soft-start capacitor size (to compensate for #1 above.)
3) Change oscillator components to increase voltage stability.
4) Add a TI TPS2829 MOSFET driver.
An added bonus of this is that it can now easily drive dual external FETs and possibly QUAD FETs. Testing will need to be done.

The beautifull part of it is that the FET driver can be installed piggyback on the comparator. I've yet to investigate redesigning the board.

 

[Bimmerboy]

:rock: Sounds great, Jimmy!

Missed batch 2... I WON'T be missing batch 3.

 

[CancerLad]

Just eagery waiting for these.

 

[JimmyM]

If I can just find the time now. I've got a regulator design to work on as well as finish a Mag458 mod for a CPFer. I'm so close with the regulator I can taste it. It just reacts too slowly. Current design is good for 14 volts input, but I already have a different FET driver that's good to 18V. I recently found a PWM controller that will go up to 52V and has a built in P channel FET driver with a -8V limit for the FET gate. Only drawback is that only goes to about 95% duty cycle (97% RMS). That means that it can never be fully on. This isn't a problem when the pack voltage is always above the desired bulb voltage. Anyway, food for thought. I'm trying to keep component count down so it's easier, thus cheaper, to build. I have a feeling that AW may beat me to the digital regulation punch.

 

[Bimmerboy]

My opinion on this (though nobody asked).

To be honest, even if your driver comes out first, I believe AW will have the means to fill the regulation market much more effectively in terms of large scale availability of product; Something this niche has always been sorely lacking. Hell, people could even buy their Li-ions right along with their driver!

I also believe that even if you can sell yours cheaper, many will choose to pay the extra money for a clean looking, no hassle, drop in solution similar to his non-regulated soft-starters, and will have all the fancy features to boot (multi-levels, last-setting memory, etc.)!

This is really going to leave the DIY, low cost soft start niche wiiiide open.

Straight up NTC's? They have their issues. Rather have a "real" soft starter.

Personally, I don't want multi-levels for my Mag85... a light I've been waiting for all the "right" parts to come along for the last three years. I also don't need regulation. The cells I'll be using should easily give a flat enough discharge for any length of time I reasonably forsee using the light. I just don't want to instaflash bulbs... that's all.

A third batch of JM-SST with the MOSFET improvement from this past April would be the final "right" part for me. :thumbsup:

 

[Bimmerboy]

BTW, the preceeding post was not meant to discourage against getting a regulated driver out. With two quality products available (yours, and AW's), the variety of choice will ultimately be a good thing. However, it still would leave a lot of us looking for a simple, straightforward (in CPF terms anyway... lol) hi-po incan that doesn't blow bulbs, AND break the bank, waiting that much longer.

And, it's been a torturous wait! :hairpull::mecry:

 

[JimmyM]

No sweat, Bimmerboy. I'm not a sensitive guy. Your feedback is only what I've been thinking anyway. AWs multi-level softstarters are a great idea. especially considering the drop-in nature of them. When his regulated version comes out the drop-in convenience of them will definitley leave my "board only" regulator version lacking. His design is based on a microcontroller and a regulated version wouldn't take a lot of additional components over the soft start. Mostly programming changes. My version is "old school". Bits and pieces. It is screwdriver adjustable though.
In any case, i'm still working on the design. It's stabe now and holds voltage without overshoot. Softstart works nicely.
Who knows, maybe my niche is uber-powerful incan regulators that don't fit in a Mag light.

 

[JimmyM]

To my softstarters, I have a board design that can be submitted for manufacturing so I don't have to deal with the etching part. Things are just too hectic and money is tight.

 

[cat]

You take it easy. Talking about money is tight, that reminded me that I have to go to the gas station tonight - the price is going up by about 7% at midnight. Last month it went up about 5%. :sigh:

My v2's are still sitting unused. My bulbs from svetila never arrived, and again I found out that I don't have much time for projects.

I'm not technical enough here to explain my logic, but I think the JM-SST fits some applications that the AW switches don't.

And......... I'm such a dolt! :shakehead
My DMM needed a new battery.
It strikes me now, it needs some kind of low battery indicator. I suppose I'd have thought that it would just go dead, read zero.

 

[littlejohnle]

Jimmy,

Can i get an update as to the progress of your new soft starters.

Maybe a bit late to mention, would the new regulator or jm-sst be able to work at 6V? I recently did a 5761 build using KD 7.2v D lith batts and jm-sst (batch 2), and suprising it works very well although it is rated at input voltage >9V.
There is a good market to suit your design on this bulb as the 5761 is very touchy and prone to instaflash alot.

 

[JimmyM]

Jimmy,

Can i get an update as to the progress of your new soft starters.

Maybe a bit late to mention, would the new regulator or jm-sst be able to work at 6V? I recently did a 5761 build using KD 7.2v D lith batts and jm-sst (batch 2), and suprising it works very well although it is rated at input voltage >9V.
There is a good market to suit your design on this bulb as the 5761 is very touchy and prone to instaflash alot.

The JM-SST will work down to 6V. But at reduced capacity. The FET I use is HUGE and can deal with the load of the 5761 even with the reduced gate drive supplied by a 6V pack.
The new design, JM-SSC (Soft Start with Compensation), has been tested at 9-10V and works well. I have some testing to do to confirm operation at 6V. I need to etch a couple of prototype boards before sending them out for production.