The PhD-M6 thread (programable hotwire driver for the SF-M6) ...

[wquiles]

The PhD-M6 thread - proto board received!

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Edit: July 26, 2010

We are finishing up tweaking of various settings, so we are almost ready to start the formal sales thread. Given this, I am going to ask a moderator to go ahead and close this thread.

Thanks much,
Will


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Edit: June 28th, 2010

The production boards for the PhD-M6 V1 arrived today:

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I have been working with Alan and Jim for a couple of months on the PhD project (programmable hotwire driver) and I have always been wanting to create a variant for the SF-M6. The goal is to leverage the work done on the main PhD project thread but to tailor a version specifically for the SF-M6, since the M6 is a different beast, with unique battery choices, with two possible bulbs (MN20 and MN21), and no traditional switch like on a Mag. Here is the main PhD thread:
http://www.candlepowerforums.com/vb/showthread.php?t=209098


Of course the precursor of this project/idea/variant is the outstanding M6-R project by js, which used rechargeable NiMH cells and a hotwire driver from Willie Hunt set for the MN21 bulb:
http://candlepowerforums.com/vb/showthread.php?t=79916

We had additional projects like the PIR1 and the HDM6, so this is not the first time this has been done. Still, in my book, we still owe Jim (js) credit for not only being the first one, but for giving us the bar by which such projects are judged.

So what do we have today? It is very early, but we have an outstanding development board done by Jim and great code created by Alan. I have been modifying this code somewhat, and will be making additional modifications to make this project M6-specific:

The goal is still to have a regulated circuit with soft-start, and I would like to offer the ability for the end user to select between the MN20 and the MN21 bulbs, so that the same pack can be used with either bulb (once selection has been made). Right now I am thinking to use a switch on the battery pack and a tiny LED to indicate what bulb has been selected, but I am wide open to suggestions/ideas. We can also consider and add other features, but we should perhaps keep the initial version simple and then consider adding other "stuff"

To get started, I would like to discuss:
- what batteries we should consider? NiMH, LiIon (protected!), or both?
- should we consider again a special tailcup insert like HDM6?
- should we require an extension tube for the body as sold by FM?
- should we initially just consider the MN20 and MN21 only?
- how would be the preferred way to select between bulbs?
- what do we want the driver to do when the battery pack is depleted?

Questions, suggestions?

Will

 

[zx7dave]

I think that you will find end users that are interested in just about all the options you mentioned...
But I think the most popular would be designs that keep the M6 looking factory externally...
Maybe bring the tailcap mod back?

 

[wquiles]

I agree - the same overall form factor would be best, as Jim did on his M6-R. Here are some photos of when I made my own M6-R pack with parts that I bought from Jim:
http://www.candlepowerforums.com/vb/showthread.php?t=124058


At some point I also considered something like this one, but I don't think this could provide the amperage for the MN21:
3x 17670

And of course, the ill-fated HDM6 form factor that depended on the short tailcup. Short part in the middle, with a late model M6 cup on top and a very old M6 tailcup on the bottom:

I am also thinking that the 2x18650 holder from mdocod might be really good and maybe a version of this holder would allow a converter/driver on the sides of the cell:
http://www.candlepowerforums.com/vb/showthread.php?t=204701


Will

 

[cnjl3]

Wow!
What a great project Will. I know that this will be a success only because there are so many CPF's interested in multiple bulb/battery solutions.

I wonder though about the 18650 battery carrier-because it is "only" 2200mah of juice.

You and I have AWR's HDM6 3300mah pack which uses six AW 17500's.
Are these the Li-ions you are talking about?

My vote is for:

- Li-ion cells which might or might not need the special tail cup.
- MN21 and MN20 initially with 'JS' recommended MN15 later?
- switch to select bulb selection [damn, I am smiling as I type this]
- driver needs to shut down before cells are damaged.

A big thanks to you and Alan and Jimmy for all your hard work.

 

[wquiles]

Wow!
What a great project Will. I know that this will be a success only because there are so many CPF's interested in multiple bulb/battery solutions.

I wonder though about the 18650 battery carrier-because it is "only" 2200mah of juice.

You and I have AWR's HDM6 3300mah pack which uses six AW 17500's.
Are these the Li-ions you are talking about?

My vote is for:

- Li-ion cells which might or might not need the special tail cup.
- MN21 and MN20 initially with 'JS' recommended MN15 later?
- switch to select bulb selection [damn, I am smiling as I type this]
- driver needs to shut down before cells are damaged.

A big thanks to you and Alan and Jimmy for all your hard work.

Like I was telling Jim (js), for this project my goal is not to make money, but to put my effort/time towards finding a way to try to fulfill on the desire/need for a rechargeable, regulated pack for the M6, for all of those who were left with nothing during the whole AWR HDM6 fiasco.

You and I were some of the very few that got "something" from AWR before he ran away with the money of many here in the forums. That being said, the technical aspect of the 6x 17500 Protected LiIon pack along with the new tailcup was a sound idea, and my two packs have been performing flawlesly, and it can drive both the MN20 and the MN21, so we should consider it again for this project as a possible way of implementing this battery pack.

Will

 

[LuxLuthor]

Will, great pursuit. I think having a dipswitch to choose between the two bulbs would be fine, as it is unlikely that people will be changing bulbs frequently. I can see having 3 choices available would be even nicer.

You will get more mileage with Li-Ion's, so some combination makes sense. The 6x17500 cells gives a lot of options, and makes more sense than 2 x 18650. Ability to replace cells would make this a long term & more useful idea. (i.e. once the JS & few AWR M6-R's reach end of NiMH life, most users will not easily replace those cells.)

For long term planning, you may want to consider a platform (in terms of batteries and form factor) that takes into account some of the flexibilities that DM51's thread outlined which would work with same battery solution. I don't think it's unreasonable to consider capability of setting other voltage choices with program update in with AVR.

I would rather see low voltage cutoff at 2.8 or 2.9V for Li-Ion, rather than most PTC's set at 2.4 to 2.5V. I like the idea of PWM Low/Med/High switch controlled settings...which would require a clickie. I also like the momentary on/off pushbutton. Wonder if there is a way to use both.

End of battery either shuts off light, or reduced output for 1-2 mins then shutoff...giving you enough emergency light to do something.

Just a few ideas off the top of my head.

 

[jayflash]

The ability to use stock MN21 or MN 20 is important to me as I don't want to use bi-pins. No extension tube; that would destroy the M6 for me. Low battery warning rather than abrupt cutoff. The soft start is a plus and availability of a lower level(s) would be nice, but not absolutely necessary.

How would six 17500 cells fit or did I misread?

Good luck and thank you.

 

[wquiles]

Will, great pursuit. I think having a dipswitch to choose between the two bulbs would be fine, as it is unlikely that people will be changing bulbs frequently. I can see having 3 choices available would be even nicer.

You will get more mileage with Li-Ion's, so some combination makes sense. The 6x17500 cells gives a lot of options, and makes more sense than 2 x 18650. Ability to replace cells would make this a long term & more useful idea. (i.e. once the JS & few AWR M6-R's reach end of NiMH life, most users will not easily replace those cells.)

For long term planning, you may want to consider a platform (in terms of batteries and form factor) that takes into account some of the flexibilities that DM51's thread outlined which would work with same battery solution. I don't think it's unreasonable to consider capability of setting other voltage choices with program update in with AVR.

I would rather see low voltage cutoff at 2.8 or 2.9V for Li-Ion, rather than most PTC's set at 2.4 to 2.5V. I like the idea of PWM Low/Med/High switch controlled settings...which would require a clickie. I also like the momentary on/off pushbutton. Wonder if there is a way to use both.

End of battery either shuts off light, or reduced output for 1-2 mins then shutoff...giving you enough emergency light to do something.

Just a few ideas off the top of my head.

Thanks - excellent ideas and suggestions. Since I will be using the Tiny85 controller, those settings would be easy to set.

What did you mean by this: "I like the idea of PWM Low/Med/High switch controlled settings.." what exactly you have in mind? Driving the specific bulb at a lower point than its rated voltage?

I also went ahead and posted an invitation in DM51's thread you linked to get additional feedback

Will

 

[wquiles]

The ability to use stock MN21 or MN 20 is important to me as I don't want to use bi-pins. No extension tube; that would destroy the M6 for me. Low battery warning rather than abrupt cutoff. The soft start is a plus and availability of a lower level(s) would be nice, but not absolutely necessary.

How would six 17500 cells fit or did I misread?

Good luck and thank you.

You did not misread. You can fit six 17500 LiIon cells, in three parallel banks of 2x serial cells each, which even when using protected cells (and with the soft start) allows enough drive current for the MN21. Of course, there is a small catch - namely that the original tailcup's insert has to be swapped out for a smaller (less tall one) which then allows the longer battery pack to fit inside the M6 without any body extenders. That is what I meant in my post above when I posted this picture showing the shallower tailcap insert:

Will

 

[LuxLuthor]

Thanks - excellent ideas and suggestions. Since I will be using the Tiny85 controller, those settings would be easy to set.

What did you mean by this: "I like the idea of PWM Low/Med/High switch controlled settings.." what exactly you have in mind? Driving the specific bulb at a lower point than its rated voltage?

I also went ahead and posted an invitation in DM51's thread you linked to get additional feedback

Will

Will, I meant along the lines of AW's multilevel driver. When you start using its 3 settings, like many LED driver options, you realize there are many changing scenarios that benefit from reduced/higher outputs. Admittedly, I don't use the 30% duty cycle setting all that often with incans because the color is too orange, but I flip between the 60/100% a lot. I suppose the better settings would be 40/70/100% duty cycle.

 

[LED61]

Will, believe it or not (I have already talked to Jim about it) I have been running my MN21 with the 7.5V regulated pack I bought from you (thanks so much). The runs have been limited to 1 minute and the bulb lasted about 7 hours total time in 1 minute bursts. The issue was that the heat created blackened my first MN21 and to avoid this I did not do extended runs.

But I would be willing to bet that with the soft start the MN21 could run at 7.0V with more decent bulb life (15-20 hours ?). We'd be driving it harder that the M6-R at 6.8V but I'd gladly trade the lower lamp life for a more white beam.

 

[tumblingdice]

Hi Will - An outstanding project. Having an M6 powered by 6X14500 cells is an excellent idea. My pennies worth: Avoid altering the external appearance/size of the fabulous M6 design. I'll be watching developments in this thread with great interest. Best of luck - Tumblingdice.:twothumbs

 

[tumblingdice]

Oops - that's 6x17500 cells.

Hi Will - An outstanding project. Having an M6 powered by 6X14500 cells is an excellent idea. My pennies worth: Avoid altering the external appearance/size of the fabulous M6 design. I'll be watching developments in this thread with great interest. Best of luck - Tumblingdice.:twothumbs

 

[DM51]

Great project! I've added a link to this in the shootout thread.

The safe high-current IMR18650 cells from AW would be a very good choice for the MN21.

 

[BSBG]

Here are my thoughts...

• Keep the form factor unchanged. I have a 2C extension and really don't like it, in spite of the admirable run time with the MN20 or a WA1111.
• The monetary option is important - one of my only objections to AW's 3 level soft starter is that it is constant on only.
• Less than 15 minutes on the MN21 is too little IMHO.
• Another option is 3x17670 with the MN60 and 61 - not too much current draw and a beautiful white light. Taking a couple of tenths of a volt off the pack and the soft start should extend the bulb life considerably.
• Teh 6x17500 is viable if the modified tail cup can be made readily available, or part of a kit.
• The bipin options on either 2 or 3 Li Ion should be considered - the WA1111 or 1331 are good alternatives to the SF bulbs.

I am sure more will occur to me...

 

[brunt_sp]

So far as running the MN21 is concerned, what is the advantage of the 6 X 17500 over the 2 X IMR18650 ? Is it just runtime ? Is softstart really necessary ?
I gather that the real aspect of this proposal is the regulation so there will be constant brightness level throughout the runtime of the cells - Interesting.

 

[wquiles]

So far as running the MN21 is concerned, what is the advantage of the 6 X 17500 over the 2 X IMR18650 ? Is it just runtime ? Is softstart really necessary ?
I gather that the real aspect of this proposal is the regulation so there will be constant brightness level throughout the runtime of the cells - Interesting.

Good questions. Nothing is perfect, but here are some advantages of the 6x17500 pack over the 2x18650:
- 6x 17500 gives you more capacity, so yes, longer runtimes.
- 6x 17500 sags puts less stress on the cells (each cell sees 1/3 of the rated MN21 current over 100% of the rated current for the 2x 18650)

Is soft-start really necessary? In my opinion, yes. I would not bother working in this project if we did not have it:
- Imagine that you "really" need the light to come "ON" - do you want to mess with double/multiple taps until you can fool the protection circuitry of the cells, or do you want a light with a soft-start so that it comes "ON" every time?
- A well implemented soft-start circuit extends the life of the bulb - pretty important in my book. It is during the initial ON that you have the highest risk of blowing the bulb.

On top of the soft start, we then of course use regulation to keep the bulb at the optimum voltage while the batteries drain, and with regulation using a micro-controller (Tiny85 in this case), we can also easily incorporate a low battery monitor which would protect the battery pack from over-discharge.

Lastly, another important factor in favor of regulation is that you can operate a bulb using a battery pack with a higher voltage than the bulb. That first photo on post #1 shows a bulb rated at about 5 volts happily being run from a 12 volt supply. Solutions like the 2x18650 (as shown by member mdocod) really over-drive the MN21, so you are already increasing the risk of killing the bulb, and of course this shortens the life of the MN21 bulb. With a regulated circuit, you keep the voltage to the bulb at a set point so you eliminate this over-driving condition..

Willie Hunt's "legendary" LVR did all of this, although it did not have the ability to be used with different set voltages/bulbs. We are just trying to duplicate it, and to provide the ability to have multiple voltages

Will

 

[leukos]

Will,

First of all, thanks so much for the hundreds of hours you, Alan, Jim and put into this project already! :bow:

I'll give my quick answers to your questions:
- what batteries we should consider? NiMH, LiIon (protected!), or both?
LiIon is the way to go, more energy density and less weight. 3x 17670 batteries is the most you can pack in there without modification, though I really do like the simplicity of 2x 18650 (6x 17500 is just too many batteries!). Besides, huge battery improvements seem to be around the corner, with all the talk of nano silicone wires we may soon have 18650's that can power the MN21 for 8 hours on a charge. Unlike js' M6-R packs, it would be nice if it wasn't a shrink wrapped kit, but something that we could pop the batteries in and out of for charging.

- should we consider again a special tailcup insert like HDM6?
Keep it simple and stock for now.

- should we require an extension tube for the body as sold by FM?
Keep it simple and stock for now.

- should we initially just consider the MN20 and MN21 only?
How much trouble would it be to make the Vout variable? With FM's excellent bi-pin adapters, there is a plethora of lamps I would like to experiment with at various voltages. I really would like a low powered lamp option with runtimes of up to four hours if the voltage could be user selected.

- how would be the preferred way to select between bulbs?
A switch makes sense if you only plan to offer two options.

- what do we want the driver to do when the battery pack is depleted?
I have always thought that blinking renders the flashlight useless. Makes more sense for there to be a moon mode for the last few minutes before cut off.

 

[Grox]

Thanks Will and everyone else who's been working on the PhD project. I have looked at that thread many times but have never been able to contribute constructively, lacking the knowledge.

Here's my 2 cents:

- what batteries we should consider? NiMH, LiIon (protected!), or both?
Li ion.

- should we consider again a special tailcup insert like HDM6?
I'd prefer not to have an insert. I appreciate the ability to swap out rechargeable packs and go back to primaries without having to fiddle with a tailcup. KISS is a good approach at least initially. Perhaps that could be an option further down the road.

- should we require an extension tube for the body as sold by FM?
Again, I'd prefer the M6 in stock form.

- should we initially just consider the MN20 and MN21 only?
For me, the most crucial feature would be MN20/21 support. However, it would be very handy if other bulbs could be powered. I'd love a variable Vout.

- how would be the preferred way to select between bulbs?
Switch or pot for variable Vout. Or... computer interface :candle: As simple as possible please!

- what do we want the driver to do when the battery pack is depleted?
It would be lovely to have a low batt indicator for example a dim pulse every few seconds.

 

[wquiles]

It is of course early, but so far:

- most want to use LiIon cells

- seems like most want to keep the overall original size of the M6 as is, with no extensions. Some are willing to replace the tailcap insert to gain more capacity (7x17500)

- most want to support the stock MN20/MN21, and some want even more bulb choices

- most like the idea of a simple way to select bulbs by the end user


Let me talk more about the voltage selection, since most of you are familiar with the AW soft-start/multi-level Direct Drive PWM circuit, the FluPIC, and LED drivers from TaskLED. If you go and read the PhD thread, you will note that the "normal" PhD platform (which from now on I will just call the PhD - I will continue using PhD-M6 for our unique variant) assumes the following:
- that the host is a Mag
- that the Mag has the switch converted to momentary (like we do for the drivers from TaskLED)
- that the battery is always connected to the micro-controller (which from now on I will call the Tiny), and it is constantly looking at the momentary button to determine when to turn ON, OFF, etc..
- that there are almost infinite battery possibilities (OK, I am exaggerating a "little", but clearly having anywhere from a 1xC to something like the Elephant means far more battery alternatives than for the M6 host).


In the PhD-M6, since we want to keep the basic flashlight "as is", we have to consider some limitations that come from this unique form factor:
- We don't have a simple way to both having a momentary button AND having the battery always connected to the Tiny. If you release the button on the M6 the circuit is open and the bulb does not get to stay on. So the M6's switch can't be considered "momentary" - it is either ON or OFF, and in our case OFF means the circuit is open.

- For the M6, we have very few battery alternatives if we stick with the OEM body configuration, so this makes the design of the PhD-M6 both simpler, but also more limited compared to a Mag host.

True, for multiple levels we could come up with some solution like on the FluPIC where multiple taps get the driver in various modes, but unlike the FluPIC and the AW driver, the PhD-M6 is a buck regulator, so it "can" output a voltage higher than the bulb can take – a mistake in the menu and/or sequence of presses/taps could result in a very expensive blown bulb!

When Jim (js) came up with the superb M6-R, he wired the LVR from Willie Hunt so that it would be connected to the battery pack, and the main switch would just close the circuit and turn everything ON. The LVR was programmed for the MN21 (set to 6.8V rms) and that was it – nothing to select. It just worked. Simple. Reliably. No double taps

At least to start, I am looking at a similar, very simple solution that works the same way for the PhD-M6. Here is my initial proposal (please feel free to punch holes in this, agree, disagree, offer alternatives, etc.):
- Each PhD-M6 will be wired like the M6-R, in a very simple manner. No assumption of multiple button presses. Just ON and OFF, just like the M6 works today.

- The PhD-M6 will provide a regulated output via a varying duty cycle PWM signal, and it will also offer a soft-start. For example, you can run a 7 volt bulb from a 12 volt supply.

- Each board will have two dip switches (or something similar, but changeable for the user), to select one out of 4 possible bulb combinations.

- Each time the Tiny in the PhD-M6 wakes up, it reads those values, and sets the output accordingly:
0 0 – bulb 1
0 1 – bulb 2
1 0 – bulb 3
1 1 – bulb 4

- Battery low level set depending on the battery solution used (9x NiMH, 7x 17500, 2x 18650, etc.).

Note: If in the future we have more battery choices, we could then use the next higher pin count Tiny processor (with more additional inputs) and have two or more battery alternatives. At least for this first iteration, I would like to suggest that we keep it to just one battery pack so that we can get the project moving along.

Why I am thinking this would be a good way to get started:
- This initial solution would therefore require no double taps, no alterations to how the M6 works today

- You would not have to set the bulb choice, nor the battery alternatives via button presses/multiple taps. You can't accidentally change those values by getting confused on the menu. Remember that here the driver "can" output a higher voltage than a bulb can take.

- If you forget what bulb you have programmed now, simply "look" at the battery pack and read the dip switches. This will prevent "ops" when assembling different bulbs in the M6.

- Keeping it to just a few single alternatives will be quicker and simpler to manufacture and implement.

OK, so lets hear it. Ideas/suggestions/changes/alternatives?

Will