Flashlights/Step-Up for violet laserdiodes?

[krutzbeuazen]

Hi,

I am playing with my prrrecccious violet laserdiode. I read too late that there is that new version of DX' Elly flashlight, which is not capable of outputting the needed 5v with enough current, which I can confirm.

I couldnt find much info about other flashlights or their converters..
I would like a converter which uses 1.5v input like the Elly. A nicer (=slimmer) body would be appreciated as well! A flashlight which takes a CR123a or CR2 would be nice, too.

So, which flashlight would drive a violet LD as well? Anything from DX or Kaidomain would be much appreciated, since most nice flashlights are not available here in Germany.

Thanks in advance!

Manuel aka Krutz

 

[Corona]

If you feed the new Elly circuit with more than 2V, it will power a violet LD OK. But you still need to make some simple modification to the circuit to avoid sending voltage/current spikes to the laser diode. I've posted details on that, which you probably have seen.

For example, a CR123 battery powered flashlight will work OK, if you can fit the Elly boost PCB inside, because the voltage is 3V. The new Elly boost will raise this to about 7V...

 

[krutzbeuazen]

Hi Corona,

thank you for your reply!
yes, i read all i could find, and i read your name many times! thank you very much, on this way!
my initial plan (after discovering that 1.5v isnt enough for an elly) was to use a cr123a or better cr2 cell. but then i need a different host, and then i can get a lamp with a suitable converter for 1.5v as well.
here its so bad with buying flashlights in shops, that you cant really get *anything* which uses a single cell, be it 1.5v or lithium. so i have to order online anyway.

by the way and topic:
obviously the small AAA dorcy light works for the violet LD. those two (old Elly and dorcy) were the only names i found out, so far.

since the old luxeons have a high voltagedrop, any driver for those should be suitable, i believe? can anyone comment on this?
and yes, please, anybody playing with those LDs, read about how to make those converters safe, and take care about ESD!

any hint is much welcomed!

manuel

 

[Corona]

The Bluray (violet) laser diodes have a voltage drop of almost 5V, and Luxeon whites are only about 3.7V.

UV LEDs have a similar voltage drop and can be used to test a driver to see if it will work with a Bluray laser diode - if it won't drive the ultraviolet LED to >40mA, it won't work with a violet laser, either.

The 3-cell (4.5V) LED flashlights won't work with UV LEDs or violet laser diodes, of course.

You COULD use a Lithium thionyl chloride (3.6V) AA, and then won't need to change anything about the Elly, mechanically, and have plenty of voltage to operate the Elly boost.

Here's a link to some suitable Lithium batteries; hopefully there is a supplier near you that also has batteries like this (maybe you can find them without the solder tabs, which will need to be removed to fit the Elly):

http://www.all-battery.com/index.asp?PageAction=VIEWPROD&ProdID=1375

 

[krutzbeuazen]

yes, true with the regular luxeons. i meant the luxeon 5w, which has a drop of over 6v. obviously, there wont be a flashlight with a lux 5w and only a single cell, since it would need, uhm, over 4 amp? such a lamp would have some slight problems with runtime, heat, and exploding batteries, i guess! *smile*

anyway, perhaps i find a 5mm led lamp which produces up to 5v.. the dorcy aaa has a single 5mm led as well.

with such cheap converters on DX/KD and rel. cheap complete flashlights, it would pay off very fast, instead of looking for expensive (here) 3v primaries, or a even a charger extra. but then, if nothing else works, i'll have to get 3v cells.

thinking about it.. i have a cheap+noname singleAA 5 LED lamp somewhere.. lets see how much voltage it puts out!

i'm surprised noone has a hint about flashlights.. i read quite many posts with people playing with these bluray diodes? am i the only one trying to build a pointer with it?
would the electronics or LED thread be more suitable?

anyway, will keep all readers updated..

manuel

 

[Corona]

I did not realize that the Lux 5W have such a high voltage drop! It does somewhat explain why the new Elly boost goes to 7 volts (although this is 7V only when unloaded, with a single 1.5V cell)

I've built a few violets around the Elly, and there are a few others that have done this with the Dorcy, and some other platforms, but it seems most guys are more interested in a laser that burns things, than a violet laser.

So there are many "DVD burner" red laser / flashlight-based designs here, but few Bluray projects. Also the cost of the violet laser diodes is several times that of a DVD red diode, another reason you don't see many violet efforts. The drive circuit approaches taken by many of the DVD-red efforts would result in instant destruction of a violet laser, so it's probably a good thing not too many of us are trying their hand at a violaser...

So you are among the elite few who are into making your own Bluray laser pointer! I am looking forward to hearing about your efforts, and what you finally settle on.

 

[krutzbeuazen]

tried it..
(after adding a zener and a capacitor).
it puts out 4.4v, and with the bluray diode on it, 18mA maximum. which seems to be exactly the lasing treshold. i had one multimeter in series with the diode for current monitoring, and another one parallel to it for voltagedrop. perhaps i would get a few mA more when removing the DMMs and the pot (which was turned all down anyway), but i'm too afraid to drive it without monitoring. so i'll just forget that driver altogether.

it was surprisingly small, diameter of perhaps 1/2 inch, or 1cm, and with only one two-pinned chip, a capacitor, and a black thing exactly the same size as the capacitor, some coil as it seems. i'm somewhat surprised my diode still lives, i tested with a red one before though.

this lamp was the only one available here, over ebay. anything else would be over 60 dollars or from international shops.


will keep you updated.. no more ideas here atm though.

manuel

 

[Kenom]

I'm trying to find a simple circuit that will increase voltage from 2 AA's currently. that and it needs to decrease teh current down to 80ma or so. I really don't wanna destroy the bluray diode. I've found a riverrock that has an ordinary led (kinda) in it and it's really small output currentwise would be ideal if it was a higher voltage.

Looks a little like this

By kenkassdy at 2007-06-22

I'm hoping you've got some idea's corona.

 

[krutzbeuazen]

Kenom:

with 3v input, you can get the driver from an elly. measure the diameter of your current driver, perhaps it fits? ellys are so cheap, you can just get one, five, and try it. if you can wait for perhaps two weeks, though! *smile*

can you post a pic of the top side of the current converter, uhm, the converter in your riverrock? at least at the elly, they connected the led at the "wrong place". for safety you will need a "big" capacitor, as big in rating as it fits your torch, any type, i took electrolytic capacitors with i think 100uF. this will make any "pulses" straight. then get a zener diode, which has a voltagerating, and if the voltage exceeds this rating, the diode will "short it away". 6v would be a safe and working rating, i think (and use). i can help you with the wiring, just so you know first what you need. or read around cpf, you may find these instructions two or three times. oh, i got me a tiny pot(entiometer) as well, 50R would be fine, perhaps even one with several "turns" to be able to set it precisely. any pot between 20R and 100R should work, if you can stuff it inside your torch as well.

sorry if i told you old news, i know i read your name in those bluray threads as well..


corona:
about bluray and dvd-burner lasers:
i was so excited when i found out about these cheap bluray drives on ebay! i already got me a projector's "dichro cube" for it, those weeks until the drives arrived were so hard to bear! unfortunately it doesnt really work to mix such a low wavelength, the (same size) dot appears like three times larger than a red one.. i'm surprised how much those few (like 65) nm change that, since i expect regular blue lasers to blend with other colors nicely..
and even worse, the reactions from friends, which i showed a violet laserdot, was, lets say, not really amazed and enthusiastic.. anyway, that wont stop me! *laughs*

 

[zeraffy]

SPAM edited out
bernhard

 

[Kiessling]

Kenom ... could you please resize that first pic to a maximum width of 800 pixels?
Thanx!
bernhard

 

[Kenom]

is this the elly you speak of? I never really did understand what flashlight was the "elly"
http://dealextreme.com/details.dx/sku.1120

OH and here's the picture of the circuit you asked for.

 

[krutzbeuazen]

howto check and use the step-up converter..

thanks for the photo, good one, everything visible!

well, i only started to "work" with those step-up-converters recently, and almost everything i know i know from cpf.. so no guarantee for anything!
(again, i write this as clearly as i can, expecting this to be read by people who dont know much in that topic yet)
what i think:
i see a resistor, a FET/transistor, some integrated circuit/IC, a capacitor, and an inductor (clockwise from 12 o'clock). this looks like the "classic" elly, which provided constant current over the batterycharge, and was good for driving laserdiodes. the IC is the real converter, everything else is just "support". it switches an external FET, the new elly lacks this, which is why its not suitable for blu-ray-diodes any more. the capacitor is only good for the IC to sense what it is putting out. its way too small to do any filtering!
the important thing is, that we can expect a regulated and constant current. i expect the output to be highly "unclean", kinda pulsed, with perhaps short pulses up to 50 volts! this is fine with the large die of a white LED, but deadly for laserdiodes.

what to do:
(this is just another version of all the infos written here already in other threads!)
get a capacitor, as large in value as possible. 33µF is ok, 100µF should be on the very safe side. a voltagerating of 9v or anything above is fine. the higher the voltage and capacity, the larger it will be. you will (I did) only find electrolytic capacitors suitable, but anything with high capacity is ok.
it will smooth out the voltage spikes, the "output" of this capacitor should be the average of the voltage it got. too small capacity: some spikes will be left.

you connect the capacitor to where the original white led was.

then get a zener diode. it will short any left pulses from the capacitor.
so you need something with a voltagerating slightly higher than the forwardvoltage of the laserdiode. in blu-ray-diodes, the forwardvoltage varies much, but a zener with between 6 and 7 volt should fit every bluray-diode.

you connect this zener in parallel to the capacitor. the mark/ring of the zener is where "positive" is. connect it to the "plus" pin of the original LED (which is "in reverse").

for security, get a big regular diode. "big" like high current, 500mA+ is good. you connect it in parallel to the capacitor and zener as well, with the mark the same as the zener, at the LED "plus". it is to short the output of the circuit altogether, if for some reason the polarity is reversed. that is to protect the laserdiode only. your circuit may fry, or the diode itself, if it is in reverse polarity output too long. a 1N4001 diode is cheap and common. if you use a 3watt-light, you may choose a diode with a higher currentrating.

you could now connect your laserdiode in parallel to the other 3 things. it would then get the maximum current that the circuit can put out at the diode's voltagedrop. this may be a good idea for a fat red (dvdburner-) diode. a bluray-diode will surely burn out instantly. so get a potentiometer and connect it somewhere between the led-out on the circuit and the laserdiode. i connected it between capacitor-plus and the three parallel diodes (zener, diode, laserdiode). that way all three diodes get a reduced current (in fault-condition). a pot with 100R should be fine. 20R or 10R for a red laserdiode (with high current needed).


i strongly suggest to first test the circuit, before connecting the laserdiode! connect the capacitor, pot, zener and diode. then measure the voltage across the parallel things. if its 5v or more, your bluray diode should work! next, measure the current, with the pot down to 0R and max resistance. if you can set it between 20mA and 100mA, you should be able to drive your bluray diode (it was the short-current, the current your laserdiode will see will be lower).
however, you still dont know if the output still has spikes (ripple).
before risking an expensive laserdiode, connect an inexpensive one. you can put some diodes (any will do) in series with your red laserdiode to simulate the higher voltagedrop of a bluray laserdiode. try 3 diodes in series for example (4.5v bluray-drop - 2.5v red-drop = 2v # 2v : 0.7v per diode = 3 diodes).
if your red laserdiode dies, something is wrong. if it survives, chances are good, that your bluray-diode will too.

important with all step-up converters:
NEVER connect the battery, and then the laserdiode! the charged capacitor will immediately, and unavoidable kill the laserdiode! i "checked" this with a dvd-burner diode.. aww. to be on the safe side, short the capacitor/wirtes where the laserdiode will go before connecting the laserdiode, and connect the battery afterwards.


since i couldnt run my bluray-diode with that new elly circuit, i connected a(nother) red dvd-burner diode instead. without resistor/pot at all, it gets around 200mA, and works fine.


i guess i will have to order one of all flashlights from DX, and check their suitability by myself..

questions, or hints, anyone?

manuel

 

[Corona]

One addition - you need a schottky diode in series with the inductor / filter capacitor circuit - the LED served this rectification function and without it, the capacitor will see very high ripple currents and will actually discharge through the inductor to the FET during the FET ON time (energy is transferred from the inductor to the capacitor during the OFF interval in a boost topology switching supply).

Like this: inductor output to diode anode, diode cathode to capacitor (+), capacitor (-) to circuit negative

The parallel zener is a good idea but may not be needed; the capacitor will do a very good job of suppressing the voltage spikes. A "pi section" filter will go a long way to make it even better - this is another capacitor to negative, after the current limiting resistor (directly across the laser diode), and doesn't need to be very large (0.1 to 1uF is fine).

Best way to test the circuit is with a blue or UV LED, having a similar forward voltage drop and current demand as the Bluray diode.

BTW, the threshold current of all the BR diodes I've used is in the 25-30mA range and you want to drive the LD at around 35-45mA. More if you're a gambling man

 

[krutzbeuazen]

I still didnt give up - no way with a violet lasing beauty waiting!

so i ordered four flashlights from DX, all powered by a single AA cell, with a one watt emitter, and all around 4 dollars. the first arrived today, the others will come in four days, i hope. the first one has the same emitter as yours, kenom, shown above. has a "big" electrolytic capacitor, an inductor in the same dimensions, some tiny smd thing which could be anything from a resistor to a transistor, and, ladies and gentlemen, some IC under a blob of epoxy!
it is nearly impossible to open the head without damage, unfortunately.

i will post pics and results from this one soon, i hope not later than weekend. and the other three flashlights will follow eventually..

manuel

 

[dr_lava]

I'm looking forward to your results. They could directly relate to those in the new group buy

 

[krutzbeuazen]

Bad news..
today the last three flashlights arrived. i opened them up (one with a dremel), two had ugly unregulated simple circuits (one coil, one transistor, nothing else). the other two looked better. one had what seems to be a chip, the other one had two transistors (or whatever). i tested them with leds, then a red LD, then the violet LD.. both put out 25mA maximum, exactly as the elly. so, all three (zhe two new ones and the elly) arent even enough to reach lasing treshold for bluray LDs. i made pictures, but sincethey wont work anyway..?

i looked through DX before ordering, and am quite sure to have found all different 1AA flashlights with a 1w emitter.

they are:
elly
1W 1xAA Flashlight Black
1W LED AA Flashlight Black (B-1W)
1W Mini AA Flashlight (Black)
1W LED Flashlight Black (AA)


so.. we need either more voltage-input for those circuits, or some better working circuit, or "direct-drive" with 9v input and currentlimiting?

damn..

*clue- and hopeless*

manuel

 

[dr_lava]

I have looked at an elly circuit before.. is it possible that you can boost it by modifying the feedback or increasing the inductance?
If I remember right the elly goes to 5V open circuit, in an almost regulated manner.

 

[Corona]

I've covered this before, do it one more time for the new guys and forum-search-challenged:

The problem with the new Elly (and others) is the "switch" element in these boost circuits (the internal FET or transistor in the boost controller IC). These do not have a low enough ON resistance (low enough voltage drop) to provide adequate energy storage in the inductor during the ON time. When the FET turns OFF, this stored energy is released to the load, through the rectifying diode. The ONLY way to make these work is to increase the input voltage. 2 cells (3V input) works FINE.

The old Elly circuit with the external FET worked fine too, with a single cell (1.2 ~ 1.5V), but this cost the maker more micropennies and was thus "improved" in later circuits. It only put out 5V, which was barely adequate for a violaser, but had enough guts to make 5V @ 50+ mA no problem.

The later Ellys are regulated to 7V (no load) and would be ideal if it were not for the weak FET inside the IC. As a regulated boost converter, their load curve just plain sucks, due to the weak FET. But - I bet it matches the 1W white LED's voltage/current curve very well - which is, after all, what it's been designed for...

So...in anticipation of "why not add a better FET to the design"? Because the output signal from the boost controller needs to also be inverted to use an N-channel FET. Do-able, but a significant mod, to a tiny circuit. And being a high-frequency switcher, you cannot spider-wire parts onto the board, and expect it to work very well unless it is very carefully done (this is why trying to measure the current in the LED results in all manners of senseless readings; and instability - the meter, probe wires, etc. all add parasitic inductance and capacitance to the circuit, and most DMMs are themselves incapable of accurately measuring the resultant complex (garbage) waveform).

The "right" thing to do is design and build a suitable boost circuit, electrically and physically, specifically for the application. And if I had more free time (OK, ANY free time), I'd do it, and sell them someplace.

I may try modding a new Elly with an external FET kludge, if there's interest from the community from those that understand this is NOT as easy "pot mod" type undertaking and are still willing to perform the microsurgery...

??

 

[RDZombie]

has anyone taken a look at the "loose" boost boards DX sells, I bought a bunch of different ones with 1.5v input to experiment with but have yet to actually get around to it. Ill try to snap shots of the different boards and post em up. A couple of them look pretty promising.