IR Diode Driver

[thehaag]

Hi All,

Im fairly new to electronics and would like to build my own laser driver however, I need to to supply an input of 2.2V and 1Amp how could I achieve this??

thanks

TJ

 

[thehaag]

Circuit driver/regulator for LASER Diode

Hi all. would anyone here know how to make a laser driver/regulator that would support 2.2V and 1A to IR diode I'm trying to power I'm fairly new to electronics have basic experience with them but still a newby. Im doing this purely for educational purposes.

 

[Menticol]

Take a look of this bible

https://www.repairfaq.org/sam/laserdps.htm

If you have any question about any type of laser, Sam is the way to go

 

[Sceadwian]

With a constant current power supply that can provide 1amp at around 2.2 volts?

 

[Joe G]

look up lm317 or lm338 regulator, should give a start, the data sheet has some examples.

 

[thehaag]

Yes. I don't mind buying one first then building one but i cannot find anything. battery + driver (needs 2.2v and 1A current) + diode right?

 

[thehaag]

Would a ghostdriver2 power it? Im unsure because of the high voltage and current that it has... over 2.2v and 1A... i don't mind buying one before i build one just to test some things out.

 

[Menticol]

2.2 v is not very high voltage.
Some types of laser require monstrous high voltage and high current power supplies. So big that they cannot provide that power continuously!

I was about to suggest you the LM317 on constant current mode
http://users.telenet.be/davshomepage/current-source.htm

Keep in mind that the voltage and current not only affects the laser brightness, also its service life. Providing a heat sink for the diode may be also required.

Read the article at Sam's site
http://donklipstein.com/laserdps.htm

The following four possibilities exist for the laser diode drivers inside laser pointers. (Unless otherwise noted, this applies to red laser pointers, not the DPSS green types with their high power laser diode pump requirements.)

Series resistor: There is no active regulator. A resistor limits current to a safe value with a fresh set of batteries. The laser diode is driven like an LED. As the batteries are drained, current decreases proportional to the difference between the battery voltage and the diode drop (about 2 V) divided by the resistances. Since output power and thus brightness would also decline dramatically with battery use, this approach is only found in the cheapest of laser pointers. See the section: Laser Pointer with a Resistor for a Regulator.

Constant current: Laser diode current is set to a safe value between threshold and maximum. This takes care of battery voltage variations but still would have problems with changes in the laser diode output with temperature. This is rarely, if ever, found on red laser pointers but is used for green laser pointers since the high power pump diodes for the DPSS laser module do not have or need optical feedback for adequate regulation.

Optical feedback - unregulated reference: Some laser diode drivers use the monitor photodiode to control laser diode current but do not have constant voltage source like a zener diode circuit to use as a reference. This is fairly safe for the laser diode as long as the correct battery types are used. For these, output brightness will vary somewhat with battery voltage and will thus decline as the batteries are drained.

Optical feedback - regulated reference: The best designs (and all those using IC driver chips) will maintain nearly constant output power until the batteries are nearly exhausted.
I'd expect to only see (3) and (4) in modern red laser pointers with (4) predominating in more modern designs. Expect (2) in green DPSS laser pointers (but many or most of these will also be pulsed)."

How are you going to measure the diode's performance? It's IR!

 

[dr pepper]

The third schematic down on this link is a constant current source that will give 1 amp.

You could power it from a 12v battery, the efficiency will be horrible and you'll need a large heatsink, but its a start to get the thing working and only uses 2 components, the resistor needs to be 7w min.

A 2.5a fuse is also a good idea in case something shorts.

https://www.google.co.uk/imgres?img...a=X&ei=XRyaT930IJLT4QTJ-_WqDw&ved=0CDsQ9QEwBQ

 

[thehaag]

I don't know as of yet just trying to get it working first, was hoping someone could give me a diagram that i could follow??

 

[Menticol]

As Joe told you, an LM317 will do the trick. Somewhat unsafe way, but it will do.

**broken link removed**

Much better if you use it as a constant current supply, see the link on the previous post.

Just curious, how are you going to measure the diode's output, as IR is invisible?

 

[thehaag]

thanks Dr. Pepper, I'm extremely basic with this but i have a massive heatsink for it so ill be okay with that. so input would be the battery? whats the 220nf? and output would be wired to my diode but its got a positive and negative leg

 

[thehaag]

im guessing IR 808mw is visible

 

[Menticol]

No pal, your eyes will only see wavelengths from about 390 to 750 nm.

You can use that IR light to pump a die and only then obtain (for example) green, but that's black magic for everyone except laser hobbyists.

Better if you use a blue or red laser from a CD or Blu-ray unit to experiment.

 

[Sceadwian]

12 volts why??! He only needs 2.2 volts, the drop out voltage of of the 7805 is 2.5 volts, so all he needs is a 5 volt supply, it'll only dissipate 2 watts, might not even need a heatsink. The diode itself more than likely will.

 

[Menticol]

He posted the same question over and over!

 

[thehaag]

Sorry im new to this site and I was insure where to post.