Diode blanking....

[Sourcegeek]

Hi!
In a few days i'll shop a 50mW green laser pen and i'll use it on my homemade projector (i'm not able to get a DPSS module).
I don't want to write/draw with the laser, i just want to make nice beams, so I was thinking on extracting the diode module of the pen and connecting it to a transistor, then the transistor to the parallel port and with the PC make blanking like each ms.
So... Is there any danger of breaking the diode because the fast on-off like bulb?

Thanks

 

[chipdouglas]

you should be fine. but better if you had a driver capable of doing this and not just turning the laser on and off quickly.

michael.

 

[Bionic-Badger]

The transistor should work fine and is probably the safest method of regulating current to your laser short of a full driver. I would make sure that there is a maximum current that can be passed to the laser so that you only need to worry about on and off states.

 

[Sourcegeek]

Hmm
I'm not using the transistor for regulating current, i'm using it for increasing the parallel port voltage. For protecting the port i'm using a diode
I'm just worry about the laser diode

 

[Benm]

You need to regulate the current to the diode whenever its active - that applies to both CW and pulsed operation. Post some schematics of your setup so we can have a closer look at what you are doing!

 

[Sourcegeek]

Hi
I'm using something like this:

 

[Bionic-Badger]

That circuit topology may be dangerous if you're using a bare laser diode. It should be okay for a green laser if you're connecting to the driver.

If you use a bare laser diode, you might want to construct something like this. Then you can apply the blanking signal to the PWM input, while ensuring that the full-on state will be current limited. Those transistor parts can be swapped out for alternates, and the post tells you how to tune the circuit for your needs.

 

[Sourcegeek]

Bare laser diode? Sorry but, what do you mean?
I will get a Green Laser pen and extract the Diode and the driver for it.

 

[chipdouglas]

when talking about greens you should say "module" as of now we don't have green diodes a the hobby level.

bionic was saying your schematic doesn't look good if you are going to use only that and not a driver. by bare diode he means a diode like a red, violet, blue... that is not already hooked to a driver...

your green is a module that has an infra red diode, a crystal set and a driver. and because your green already has a driver he is saying he thinks your drawing should be fine as long as you use it with your driver too.

michael.

 

[Sourcegeek]

Ok, ok..
Now, final question.. I think a Green Pen has a driver, i am correct? I mean, the one that has the pot and so and so..