tester97
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Joined: Fri May 16, 2014 2:49 pm

Make Logic High (>3V)

Wed Aug 06, 2014 5:47 pm

Hello,
I'm building a laser circuit and it says the Laser is only on when "A" is logic high (>3V).
Where do I have to connect A and how do I programm it?.
Greetings tester97

rgrbic
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Re: Make Logic High (>3V)

Wed Aug 06, 2014 5:53 pm

You should provide more details about laser and driving circuit.
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rpdom
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Re: Make Logic High (>3V)

Wed Aug 06, 2014 5:56 pm

Have you got a link to the specifications for the laser?

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davef21370
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Re: Make Logic High (>3V)

Wed Aug 06, 2014 6:02 pm

What kind of laser is it? Do you have a part number?
Some lasers are switched on just by powering them up, others have a constant power supply but are switched on and off (modulated) by a separate source eg. 3V logic.
If it's the latter you could possibly switch it from any of the GPIO pins but the former will probably need an small switching circuit.

Dave.
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Burngate
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Re: Make Logic High (>3V)

Thu Aug 07, 2014 8:06 am

The GPIOs put out 3.3v. That may be enough above 3v to work.
If not, you'll need a transistor of some sort - look for level shifters, as used for I2C for example.

tester97
Posts: 7
Joined: Fri May 16, 2014 2:49 pm

Re: Make Logic High (>3V)

Sat Aug 09, 2014 3:52 pm

Thanks for the replies.
This is the Laser Circuit i build: http://1.bp.blogspot.com/-ewI7TGlE0q8/U ... driver.png Its the 650nm red laser from a dvd rw.
I used a 470 Ohm resistor because i didn't find a 500 ohm resistor in my country, I hope that will work too.

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