Pages: 1 [2] 3   Go Down
Author Topic: Rapidly spinning laser to create one-lined image  (Read 1710 times)
0 Members and 1 Guest are viewing this topic.
Dubuque, Iowa, USA
Offline Offline
Edison Member
*
Karma: 45
Posts: 2474
View Profile
 Bigger Bigger  Smaller Smaller  Reset Reset

The Transistor as Switch section shows setup. Also read the "Connecting a transistor from the output of an IC" for an explanation of what's going on. Heck, read the whole page and you'll be a lot smarter in the end smiley-wink

The current drawn by a laser pointer is very low so pretty much any N-channel transistor you have will work.
Logged

Phoenix, Arizona USA
Offline Offline
Faraday Member
**
Karma: 39
Posts: 5557
Where's the beer?
View Profile
WWW
 Bigger Bigger  Smaller Smaller  Reset Reset

Something like this?

Yes! Exactly. smiley

Something you might have to play with is finding the right photo-transistor; most are at best sensitivity in the IR region (look at the datasheet), but you can get ones that are sensitive in other bandwidths.
« Last Edit: May 13, 2012, 01:12:04 am by cr0sh » Logged

I will not respond to Arduino help PM's from random forum users; if you have such a question, start a new topic thread.

0
Offline Offline
Tesla Member
***
Karma: 141
Posts: 9470
Arduino rocks
View Profile
 Bigger Bigger  Smaller Smaller  Reset Reset

I've driven a cheap laser pointer using a transistor without issue. No problem switching it at 38KHz for use with an IR receiver.

Interesting. How sensitive are the IR receivers to the visible red spectrum of the cheap laser pointers?
Logged

Consider the daffodil. And while you're doing that, I'll be over here, looking through your stuff.   smiley-cool

0
Offline Offline
Sr. Member
****
Karma: 0
Posts: 340
Arduino rocks
View Profile
 Bigger Bigger  Smaller Smaller  Reset Reset

The Transistor as Switch section shows setup. Also read the "Connecting a transistor from the output of an IC" for an explanation of what's going on. Heck, read the whole page and you'll be a lot smarter in the end smiley-wink

The current drawn by a laser pointer is very low so pretty much any N-channel transistor you have will work.
Why do I need to use a transistor? If the end result is still the laser being rapidly cycled then what's wrong with just using one of the digi out pins?
Logged

Gosport, UK
Offline Offline
Faraday Member
**
Karma: 21
Posts: 3113
View Profile
 Bigger Bigger  Smaller Smaller  Reset Reset

Probably the current drawn is too high.
Logged

Dubuque, Iowa, USA
Offline Offline
Edison Member
*
Karma: 45
Posts: 2474
View Profile
 Bigger Bigger  Smaller Smaller  Reset Reset

I've driven a cheap laser pointer using a transistor without issue. No problem switching it at 38KHz for use with an IR receiver.

Interesting. How sensitive are the IR receivers to the visible red spectrum of the cheap laser pointers?
That's a tough question to answer; given the nature of the coherent beams of lasers it should be sensitive at "any" distance. I quickly got a signal at ~12 meters distance (the longest clear span in my house) without tweaking the laser focus, frequency, or power and didn't take it any farther. My goal was only to build a laser tripwire and I wasn't attempting long distance communication.
Logged

Manchester (England England)
Online Online
Brattain Member
*****
Karma: 603
Posts: 33416
Solder is electric glue
View Profile
WWW
 Bigger Bigger  Smaller Smaller  Reset Reset

Read this for driving a laser:-
http://www.repairfaq.org/sam/laserdps.htm
Logged

0
Offline Offline
Sr. Member
****
Karma: 0
Posts: 340
Arduino rocks
View Profile
 Bigger Bigger  Smaller Smaller  Reset Reset

Read this for driving a laser:-
http://www.repairfaq.org/sam/laserdps.htm
That's too much info. Why can't I buy some cheap, green laser from eBay and rapidly turn it on/off using a digi out pin (assuming the voltage is not more than the required amount for the laser)?
Logged

Offline Offline
Edison Member
*
Karma: 5
Posts: 1730
View Profile
 Bigger Bigger  Smaller Smaller  Reset Reset

Why can't you? Lol try it or search online if someone did before, I haven't tried it(couldn't get it open)  and don't know of anyone who did
Logged

Offline Offline
Edison Member
*
Karma: 64
Posts: 2465
Now, More Than Ever
View Profile
 Bigger Bigger  Smaller Smaller  Reset Reset

Why can't I buy some cheap, green laser from eBay and rapidly turn it on/off using a digi out pin (assuming the voltage is not more than the required amount for the laser)?
It's not the voltage, in that case - it's the current.
Do you have a laser pointer or a similar, simple laser module (5V or 3V) at hand?
Logged

"Hello, I must be going..."
"You gotta fight -- for your right -- to party!"
Don't react - Read.
"Who is like unto the beast? who is able to make war with him?"

Offline Offline
Edison Member
*
Karma: 64
Posts: 2465
Now, More Than Ever
View Profile
 Bigger Bigger  Smaller Smaller  Reset Reset

Getting something done with a low-power module will be a lot easier than something "high-power".
There's not a PnP, "one-size-fits-all" solution for you.
Logged

"Hello, I must be going..."
"You gotta fight -- for your right -- to party!"
Don't react - Read.
"Who is like unto the beast? who is able to make war with him?"

Manchester (England England)
Online Online
Brattain Member
*****
Karma: 603
Posts: 33416
Solder is electric glue
View Profile
WWW
 Bigger Bigger  Smaller Smaller  Reset Reset

Quote
That's too much info.
That makes me sad.
You can't be bothered to read this simplified web page. What ever makes you think you are going to understand what to do.

Quote
Why can't I buy some cheap, green laser from eBay and rapidly turn it on/off using a digi out pin
Well that page would have told you.

Quote
(assuming the voltage is not more than the required amount for the laser)?
Hint:- it is.
Logged

0
Offline Offline
Sr. Member
****
Karma: 0
Posts: 340
Arduino rocks
View Profile
 Bigger Bigger  Smaller Smaller  Reset Reset

Quote
(assuming the voltage is not more than the required amount for the laser)?
Hint:- it is.
If the laser wants 3v, then I just add the appropriate resistor right? Problem solved. Is there something I'm missing or is it not that simple? If I am missing something, why can't it be mentioned in one or 2 sentences? Like this, "That won't work because X, Y, Z"
Logged

0
Offline Offline
Tesla Member
***
Karma: 141
Posts: 9470
Arduino rocks
View Profile
 Bigger Bigger  Smaller Smaller  Reset Reset

Quote
That's a tough question to answer; given the nature of the coherent beams of lasers it should be sensitive at "any" distance. I quickly got a signal at ~12 meters distance (the longest clear span in my house) without tweaking the laser focus, frequency, or power and didn't take it any farther. My goal was only to build a laser tripwire and I wasn't attempting long distance communication.

Did you use a modular IR receiver like is used in typical home IR remote controlled electronics? If so, which particular one did you use?   
Logged

Consider the daffodil. And while you're doing that, I'll be over here, looking through your stuff.   smiley-cool

Manchester (England England)
Online Online
Brattain Member
*****
Karma: 603
Posts: 33416
Solder is electric glue
View Profile
WWW
 Bigger Bigger  Smaller Smaller  Reset Reset

Quote
If the laser wants 3v, then I just add the appropriate resistor right?
Wrong.

Quote
why can't it be mentioned in one or 2 sentences? Like this, "That won't work because X, Y, Z"
This won't work because a laser presents a varying impedance to the thing driving it and so a simple resistor will not be able to give it the constant current it needs.
Logged

Pages: 1 [2] 3   Go Up
Jump to: