Society of Robots - Robot Forum
Electronics => Electronics => Topic started by: Conscripted on March 29, 2010, 02:46:39 PM
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Good afternoon all,
I'm in the design phase of a new project. I need to connect a laser to a microcontroller and I'm not sure what the best approach is. I intend to use a cheap off the shelf laser. I suspect that the laser may draw to much power to be powered by the microcontroller itself. Anyone have any experience with this?
Thanks
Conscripted
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If you use a cheap laser could you not just use the battery that came with it and put a transistor where the switch normally is? Yes, a laser would draw to much current :)
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Hi,
I need to connect a laser to a microcontroller and I'm not sure what the best approach is. I intend to use a cheap off the shelf laser. I suspect that the laser may draw to much power to be powered by the microcontroller itself. Anyone have any experience with this?
A simple NPN transistor and two resistors will do, if the LASER can live off the same voltage as the controller. If it's a standard 3-cell pointer, a diode like 1N400x inline will drop a 5V line to around 4.35V, which should be just right for a 3-cell.
Do you need a schematic for this?
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Be careful with the super-cheap laser pointers. I've found that the laser itself has about the same operating life as the batteries. Maybe I just got a bad batch, but it could be endemic!
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Do you need a schematic for this?
A schematic would be great thanks
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Replace LED and resistor with laser:
(http://www.techshire.com/freebies/LED4dummies_images/LEDNPN.jpg)
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Hi,
Replace LED and R1 with LASER and diode, in case of a 5V supply.
Make R2 somewhere around 3k3 to 4k7.
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I just thought I'd tag this on while we're talking about it. I tried this one with a spare transitor and a cheap laser, but I didn't work completely. It was on constantly (even when it wasn't supposed to be) but it got brighter when power was applied to the transisor. Suggestions?
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Hi,
It was on constantly (even when it wasn't supposed to be) but it got brighter when power was applied to the transisor. Suggestions?
You clearly didn't drive the transistor from a CMOS output, so it didn't shut off the transistor fully.
If you just used a switch, a push button or a functional equivalent which didn't drive the base low, put a resistor (say 10k) from the base to the emitter/ground.
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I like using these bad boys:
http://www.datasheetcatalog.org/datasheet/fairchild/4N35.pdf (http://www.datasheetcatalog.org/datasheet/fairchild/4N35.pdf)
they are easy to use, and a laser malfunction won't damage your micro!
It's also a good idea to use these with serial port/USB diy projects, your ports will be safe from little errors that could damage them...
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Hi,
they are easy to use, and a laser malfunction won't damage your micro!
It's also a good idea to use these with serial port/USB diy projects, your ports will be safe from little errors that could damage them...
A transistor (in OC configuration) won't backflow a malfunction either. It's a waste of money using opto-couplers here.
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Not what you wanted to know, but still fun to watch :P
http://www.societyofrobots.com/robotforum/index.php?topic=4887.0 (http://www.societyofrobots.com/robotforum/index.php?topic=4887.0)
Robotic Cat Toy (http://www.youtube.com/watch?v=6sxnma4btrg#ws)
(http://afrotechmods.com/cheap/cat_toy/completed.jpg)