Driver or not driver ? That is the question...

[deap]

Hello,
(first sorry because my english is quite poor)
I try to turn a DVD diode into a burning laser. And i have a question about HOW to do it. My question is : should i use a driver or not ??

I did some researchs on this forum and on the web, and i found that :
- some ppl use a driver (see laserpointerforums.com/forums/YaBB.pl?num=1185701612 or youtube.com/watch?v=BI7iuBze5I8 )
- some ppl use a capacitor (cant remember the link... some guyz use a capacitor in parallel with the DVD diode)
- ...or a resistance (or a pot) (see youtube.com/watch?v=Xz4v8g6Y4mI )
- ...or a LED (see felesmagus.com/pages/lasers-howto.html )
- ...or nothing ! (see metacafe.com/watch/878163/how_to_make_a_dvd_laser/ he only uses a aixiz module + the DVD diode + 2 AAA batteries without anything more)

I will use an aixiz module + a 16 or 18x DVD burner diode + 2 batteries (AA or AAA) - what should i ass to that list ? a capacitor ? a pot ? a driver (it will not fit in a light torch!) ? nothing ? (it seems to work quite well just with the aixiz module and 2 batteries! see that last link above) :-?

Please help me because i don't know what to do !

Thanks
See you later

 

[deap]

Re: How to make a good DVD burning laser ?

Up !

I read this forum a lot since a few days, but i can't find a comparaison between driverless lasers & lasers with drivers ? Some ppl says that drivers are indispensable/essential, but other ppl made a laser without driver (but with a resistor and/or a capacitor) and it seems to work quite well (but for how long ?)

You can post here your own experience like this :

- laser puissance (in mW) + laser current (in mA)
- driver type (if any, of course)
- if you don't use a driver, then what ? a capacitor, a resistor/pot, etc.
- how often do you use the laser ?
- did you diode fry, or is it still alive ?

 

[rog8811]

Driver-less lasers are usually the ones that die quickly.......
The ones with a properly made and tested drive circuit are the lasers that give hours of enjoyment to the builder.......

- laser puissance (in mW) + laser current (in mA)
- driver type (if any, of course)
- if you don't use a driver, then what ? a capacitor, a resistor/pot, etc.
- how often do you use the laser ?
- did you diode fry, or is it still alive ?

Very bright (in mw) cannot remember (in ma)
LM317
Never felt the need to throw money away
Whenever something needs burning
Still very much alive

I am not being flipant with my answers, I built my burner some long time ago and cannot remember the figures BUT the info is all here on the forum!

Regards rog8811

 

[deap]

Actually i won't use my laser that much. I think i will use it for perhaps 20 or 30 seconds, 2-3 times a day, 1-2 days per week. Should i use a driver or not ?
(BTW, i will run the diode under-spec because i don't need much power, i just want to be able to light matches in less than 20 seconds)

 

[rog8811]

I said

Driver-less lasers are usually the ones that die quickly.......

you then said

Should i use a driver or not ?

I had previously said

The ones with a properly made and tested drive circuit are the lasers that give hours of enjoyment to the builder.......

Can you guess what my advice would be?

At the end of the day it is your choice.........................................

Regards rog8811

 

[FireMyLaser]

You should always use a driver to power your laser, PERIOD.

 

[bcroft]

i agree with firemylaser. drivers dont cost alot either. i make my own for around $5 and i bought some professionaly built ones for $4 each

 

[Gazoo]

Actually i won't use my laser that much. I think i will use it for perhaps 20 or 30 seconds, 2-3 times a day, 1-2 days per week. Should i use a driver or not ?
(BTW, i will run the diode under-spec because i don't need much power, i just want to be able to light matches in less than 20 seconds)

You may not be lighting any matches at all without the use of a driver.

 

[pseudonomen137]

You can make a boat of cardboard and duct tape - my roommate did! It may even keep you afloat for a little bit. If you don't use a driver, its like sailing in your cardboard boat. It can work - but is that type of work what you want to be trusting your diode to?

 

[pseudolobster]

drivers are more or less essential if you want to use your laser more than once or twice..

A capacitor would help to smooth out voltage spikes, though it won't protect you from excessive voltage or current.
A resistor would get you into the right current range, and will help to compensate for the fact that laser diodes have less resistance when hot then they do from a cold start, though they won't protect you from voltage spikes or other dirty power..

The best option is to use a linear regulator chip like the LM317 used in Dadael's driver, which will prevent against power spikes/surges, current drift, overvoltage, etc...
Here's the original thread with schematics and instructions on how to build one:
http://www.laserpointerforums.com/forums/YaBB.pl?num=1185701612

Bonne chance!

 

[lisaril]

Driver or not driver ? That is the question...

I have the same question as deap.

A capacitor would help to smooth out voltage spikes, though it won't protect you from excessive voltage or current.
A resistor would get you into the right current range, and will help to compensate for the fact that laser diodes have less resistance when hot then they do from a cold start, though they won't protect you from voltage spikes or other dirty power..

Since the driver is supposed to regulate voltage and current, could it be possible to combine both a capacitor and a resistor to create a circuit that 1) smooths out voltage spikes, and 2) get you into the right current range? I shouldn't have problems with overvoltage if i only use 2 AAA batteries (1.2v x 2) 2.4 volts, right?

 

[Benm]

You really should use a proper driver.

It is possible to power a laser diode off 2 penlites and a resistor, but it's not reliable at all. Battery voltage will vary with discharge, and just using a resistor will result in too much current on full batteries, too little current on partially discharged batteries, or, usually, both.

The choice is yours, but not using a driver will mean you'll either quickly destroy your diode, or not make use of its full potential in terms of output power and life.

 

[IgorT]

If you're using alkaline batteries, this means the laser is getting 3.2V when they're fresh.. The current through it would be much too high.. And it would get even worse, as it would heat up.


Still a laser like that can work for a while, but the least you would need is a cap on the LD, and some resistors between the batteries and the laser, to limit the maximum current when the batteries are full.

Since the laser diode's resistance drops, when it heats up, this means the current through it increases.. Drivers reduce the voltage slightly in this case, to keep current the same.. This means you have to use a lower current with "direct drive", so that when the LD heats up, the current wouldn't increase over the maximum. To be absolutelly safe, you would have to choose a current 20mA lower, than the one you could use with current regulation. (When i used direct drive on an LD i could see the milliamps increasing every few seconds, as it heated up.)


It also means, that as your batteries would discharge, the laser will become less and less powerfull.



A simple LM317 driver circuit solves all these problems, as long as you feed it more than 6V. You need six Ni-MHs for this, or two Li-Pos. In both cases you get 8.4V when full and 6V when empty. The current through the LD would stay constant over this entire battery voltage range. And it would never go over the one you set the driver to.


So while it is possible to safelly power a laser directly from the batteries (with a cap and a max current limiting resistos) you would have to set the current lower, than you could on a proper driver circuit and the power would be dropping all the time as the batteries discharge..




My first laser was like that, but not because i didn't want current regulation.. It was because i wanted it small. I used a rechargable Li-Po, an 1N4007 diode to drop the voltage, a 1 Ohm resistor to measure the current, a cap, and an 8 pin DIP IC holder, with it's legs soldered together on either side, and put in series between the 1N4007 diode and the 1 Ohm resistor.

This way, i was able to put different values of small resistors into this IC undercarriage, and set the current using the formula (or the calculator) in this link: http://www.1728.com/resistrs.htm


The laser still works but i didn't use it that much, and it was never on for long. Still, this solution was only temporary, and now that i'm getting AAA size Li-Pos, i'll upgrade it to current regulation, with all the benefits (especially constant power as the batteries discharge). I like my lasers, and i want to get as much life as possible out of them.

 

[IgorT]

I shouldn't have problems with overvoltage if i only use 2 AAA batteries (1.2v x 2) 2.4 volts, right?

Ni-MHs when full put out 1.4V each. The voltage would be 2.8V.. This could actually be safe for the LD, since it usually needs a little more than that - 2.835V, combined with a capacitor.. I would also recommend at least a 1 Ohm resistor in this case, for measuring the current (voltage drop across it in mV is the same as the current through it in mA, if it's 1 Ohm exactly)

From two Ni-Mhs you would probably never get full power from a laser diode, so it could actually be safe.. And if you ever put in alkalines in this configuration, the current through your laser would increase so much, that it could kill it.


But it's much safer to use a driver. The main reason i like current regulation with LM317 (besides it being safer), is the fact, that you get a constant power output over the entire battery voltage range, if you select batteries properly - 6 Ni-MH or two rechargable Li-Pos..


You can get AA or even AAA size Li-Pos from DealExtreme, which means, that combined with a 317 you can get a laser as small as it would be with two AA or AAA Ni-MHs.