PIC-O-PWM (POP) micro-P DIY & Video

djpark

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Edit: This thread started with the original Subject line "Arc-AAA-Lux Multi Brightness Multi Feature" to introduce the Arc-AAA head modded with a Luxeon and POP (PIC-O-PWM) driver. Now it is turned to a gallery of lights modded with the POP driver. The subject line is changed to reflect it.

Edit: New version of POP driver is made with more features. There is new post below.

Edit: DIY Kit soldering instruction and usage instruction video is added at later post.



I have tasted the sweetness of using PIC micro-processors to control the brightness and provide more features to the lights during H&M Contest 2004, and it rewarded me with well.

Class 2: Arc-AA 8mm ISP + Micro-P Multi Brightness
Class 4: Pager Light with 6 * 100mA LED & micro-P

Since then, I made a few more pills with 8mm led. But I have been always wanting to use the similar logic to control a Luxeon led for Arc-AA or AAA. So at last I got this done.



Arc-AAA-Luxeon-POPL with Multi-brightness, Multi-feature using PIC Mirco-Processor


- Using AAA size li-ion erchargeable battery (300mAh)
- High (300mA) and low (50mA) brightness levels using PWM
- Constant current regulation
- Turn on to last used brightness level
- Survival mode with super low current (15mA)
- Strobe mode and SOS mode

Changing brightness level is done by turning on the light, turn off within 1 second and turn on again. Current regulation is done using TPS73101 and I owe this knowledge to Doug_S.

Survival mode is not on PWM, but direct output from PIC io pin.

5th turning on triggers survival mode (dim mode). 6th turning on triggers strobe mode (5 Hz) and 7th turning on triggers SOS mode.


Head construction

arc-aaa-lux-head.jpg


I used a blank (no HA) Arc-AAA head acquired long ago and ground the front section deeper to U-shape to make it a better reflector. It is not perfect since I had to work with hand tools only, but reasonable after polishing.

I added a little epoxy to top part of the plastic led holder along the side of the dome. This strengthens the bonding of the dome to led so that it will not drop out. It also seals the dome, so it can be exposed to the environment without using a lens or optic to cover. A bit of GID powder was mixed in the epoxy, so it gives slight hint of blue-green when the light is off.

I cut a small piece of aluminum sheet to a round shape as the heatsink. It is made to be very tight fit within the Arc-AAA head cavity. I don't have thermal epoxy, so I mixed Arctic Silver 5 with Devcon 5 minutes epoxy and applied between the Luxeon slug and the heatsink. Then it is inserted in to the head with some force. Then a little more epoxy was added at the back of the heatsink to fix it to the wall. It appears to be quite acceptable. When I turn on the light on high level, the head gets warm pretty fast, but not too hot at 300mA. 700mA made the head quite hot.

The controller board has only 3 SMT parts -- PIC12F675, TPS73101 and 0.1uF capacitor. They are put on the original Arc board after stripping all parts and pcb traces. Without having a facility for pcb making, I had to resort to 3D soldering and also have to skip the reverse battery protection as used by Doug_S.

Crimp back, then the new head is ready.


Beamshots

The Luxeon I use is taken out from Arc-LSH-P and it gives very nice warm tint and I like it. I paid a big buck to get this warm tint.

Due to the poor reflector I made, the hot spot is smaller than 17mm IMS reflector and more to the flood. But it still has a small hot spot in the center and the it is quite well focused. Not just flat flood output.

The following pictures are taken with the light on the floor and 50cm away from the wall. High and low brightness with different camera setting. f2.8 2 seconds exposure gives me the picture closest perception to my eye adjusted to the darkness.

arc-aaa-lux-beam.jpg


Ceiling 3m away.

arc-aaa-lux-ceiling.jpg


To compare the brightness of survival mode.

arc-aaa-lux-level.jpg


Not to forget the strobe and SOS mode.

arc-aaa-strobe.gif
arc-aaa-sos.gif



Run time

This run time chart of the light running on High brightness level. The low brightness level is on logging now and it is still showing no sign of brightness change after 2 hours.

arc-aaa-lux-high.gif


The brightness went up a little during the initial 2 minutes. Then it stayed very flat till 45 minutes when the battery nearly got used up. The sun mode is followed by 15 minutes of gradual dropping moon mode plus long period of star mode.

Considering the battery capacity 300mAh and the current draw 300mA, this run time seems very acceptable.

One thing good about the LDO regulation of li-ion cell is that it never bring the battery voltage below 2.5V with white led since the current will simply drop when the voltage drops. So the over-discharge protection is not necessary.

Here is a logging done with 14500 (AA) li-ion battery, measured battery voltage, current draw and the relative brightness.

arc-aa-lux-14500.gif


The battery was charged during H&M Contest, that means about 6 months in storage. Then it still gave more than 600mAh worth discharge from 700mAh battery capacity.

The battery voltage dropped below 4V immediately, then gradually dropped to 3.2V next 110 minutes. During this period, the brightness and the current flow is very flat. It started showing sign of going off current regulation at 3.2V. Then 15 minutes of moon mode followed by many hours of star mode.

It indicates that the Vf of the Luxeon taken out of LSH-P is very low and the current limit of TPS73101 is very stable.

I will add run time chart of low brightness level when the logging is complete.

Enjoy!

-- dj

Edit: The current values were changed according to the actual measurement.
 

sithjedi333

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Re: Arc-AAA-Lux-POPL Multi-brightness, Multi-featu

Wow, insane work!!! This is my dream light. Any chance this is commercially available as a light or do-it-yourself kit?

/ubbthreads/images/graemlins/happy14.gif /ubbthreads/images/graemlins/buttrock.gif /ubbthreads/images/graemlins/bowdown.gif
 

AW

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Re: Arc-AAA-Lux-POPL Multi-brightness, Multi-featu

I 'm in for a DIY kit if available. Very brilliant work!!
 

AuroraLite

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Re: Arc-AAA-Lux-POPL Multi-brightness, Multi-feature

Wow, that is one sweeeeeeeet light!! Very interesting indeed! 3rd in line? /ubbthreads/images/graemlins/grin.gif
 

PEU

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Re: Arc-AAA-Lux-POPL Multi-brightness, Multi-feature

Great /ubbthreads/images/graemlins/happy14.gif

DJ, your work with PICs inspired me to start learning PIC programmming and also inspired my LEON project.

Thanks


Pablo
 

cy

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Re: Arc-AAA-Lux-POPL Multi-brightness, Multi-featu

WOW forth in line...
 

bmstrong

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Re: Arc-AAA-Lux-POPL Multi-brightness, Multi-featu

5th. I can supply you with my Arc...
 

MY

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Re: Arc-AAA-Lux-POPL Multi-brightness, Multi-featu

6th in line. I can provide the ARC with an extra thrown in for thanks.

Regards.
 

djpark

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Re: Arc-AAA-Lux-POPL Multi-brightness, Multi-featu

Thanks for the favorable comments. They encourage me a lot to go on.

To provide a DIY kit for this mod, there are a few things to consider.

The most time consuming and exhausting part of this mod is grinding the head to enhance the reflector and also cutting the heatsink to fit tight in the head. Unless someone can use a machine to shape the reflector, it is going to be your work to do.

Alternatively arc-AA head can provide adequate reflector without grinding further, just enlarge the hole.

I don't have a good source of nice Luxeon leds. I reply on a few pieces brought by local cpfers. You may have a better source. Likewise the Arc head and body. Of course you can use your own ones.

I can provide pre-programmed PIC and TPS regulator. I suggest 350mA version for AAA head, 450mA version for AA head and 800mA version for bigger lights.

-- dj
 

sithjedi333

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Re: Arc-AAA-Lux-POPL Multi-brightness, Multi-featu

djpark,

Thanks for considering the kit idea. /ubbthreads/images/graemlins/thumbsup.gif Couple of questions/comments for general discussion:
1) Can the grinding and cutting be done with a Dremel tool? If so, that would make many more people able to do it, because this tool is widely available and in the hands of many modders.

2) Buying LEDs separately is no problem, they are available from a lot of vendors on B/S/T.

3) For the head and body, could we use the Peak LED lights? These are much more available and affordable and are quite similar from what I have seen.

Overall I think this is quite doable. Thanks! /ubbthreads/images/graemlins/grin.gif
 

djpark

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Re: Arc-AAA-Lux-POPL Multi-brightness, Multi-featu

I finished the logging of the low brightness level, but find that the logged data is invalid. It went on for more than 9 hours and there was a power failure in between for 1 hour.

That also triggered me to think why it went on longer than expected. So I measured the current flow of the light and found that the initial current values posted were based on expectation and not the actual meter reading.

According to datasheet, TPS73101 has current limitation of min 150mA, typical 360mA and max 500mA. So I expected 350mA, but last 2 pieces I used gave me between 300 and 310mA current flow.

The low mode is PWM of 30% duty cycle and I estimated the current to be around 100mA. But I forgot the fact that TPS73101 has high input capacitance and about 10% of 125Hz was needed to enable the chip. So the current measured using a DMM (I don't claim to be accurate RMS) of 50-60mA is in accordance to the 20% effective PWM output.

For survival mode, a PIC io pin can source up to 25mA current. But when connected to this Luxeon, it took only about 15mA current.

So the original post is modified to reflect the actual current reading. Sorry for unintended misleading if there was any.

-- dj
 

djpark

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Re: Arc-AAA-Lux-POPL Multi-brightness, Multi-featu

[ QUOTE ]
sithjedi333 said:
1) Can the grinding and cutting be done with a Dremel tool? If so, that would make many more people able to do it, because this tool is widely available and in the hands of many modders.

3) For the head and body, could we use the Peak LED lights? These are much more available and affordable and are quite similar from what I have seen.


[/ QUOTE ]

I used a hand drill which looks like Dremel and uses the same bits.

Initially I used these at high speed. It generates a lot of heat and the head had to be fixed on a vice.

dremel-tool-1.jpg


The first one at the left is good to enlarge the front section to get bigger reflector. But the others were no good. Th aluminum was too soft and it sticks to the bits. And the last one was too soft and the bit itself was shaped.

Then I used this one.

dremel-tool-2.jpg


The round one was good. I used it at slow speed and could easily grind small portion by portion without creating heat. So I could hold the head with bare fingers to have better control.

Then I used the middle one to polish it with metal polish. The last one was soaked in the furniture wax to polish and it was used to polish the led dome.

The essence of the mod was the PIC and the current regulator, so it can be done on any light as long as the size allows.

-- dj
 

moraino

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Re: Arc-AAA-Lux-POPL Multi-brightness, Multi-featu

DJ, it's the most excellent work.

Does it work on lights with clicky? I guess not. I am thinking modding Dorcy AA. Maybe I can drill a hole in front for the switch...

Henry
 

djpark

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Re: Arc-AAA-Lux-POPL Multi-brightness, Multi-featu

Henry,

It works best with clickie actually since it is easier to press 2 or 3 times than twisting the tube.

-- dj
 

moraino

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Re: Arc-AAA-Lux-POPL Multi-brightness, Multi-featu

DJ,

I have a ASP Triad running from 18650 Lithium direct driving a Lux 3. It has a tail clicky.

Is your circuit like nFlex that cannot be used with the REAR switch because it needs both plus and minus?

Henry
 

djpark

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Re: Arc-AAA-Lux-POPL Multi-brightness, Multi-featu

Henry,

I believe ASP Triad is using incan bulb and I presume high current. I wonder if constant current has any meaning and also don't know the efficiency of PWM on the bulb (for example, half current for far less than half brightness?).

This circuit is designed to be fit in the head in between the power source and the led, so it also requires the 3 pins -- vin, vout & gnd.

If the head can be modded, it can fit easily since the size is small. Provably, you can just drive FET instead of the regulator IC from the PIC. PWM rate will need to be also adjusted.

-- dj
 

nexro

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Re: Arc-AAA-Lux-POPL Multi-brightness, Multi-featu

Very nice mod indeed. I must mention that I was already impressed when I saw the circuit a few days ago. Too bad it wasn't ready that time.

Anyway, I am in for a kit for the AA.
 
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