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Andrew P (Krazykiwi)
New member
Username: Krazykiwi

Post Number: 1
Registered: 3-2007
Posted on Wednesday, March 14, 2007 - 1:29 am:   Edit PostDelete PostView Post/Check IPPrint Post   Move Post (Moderator/Admin Only)Ban Poster IP (Moderator/Admin only)

I am having difficulties with the free space laser data transmiter. I have checked all the components and joints and all I can think of is the transistor is not the correct type. It is a 2N3904402. Is this the problem? Thank you.
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Simon Quellen Field (Sfield)
Senior Member
Username: Sfield

Post Number: 1659
Registered: 12-2004
Posted on Wednesday, March 14, 2007 - 10:54 am:   Edit PostDelete PostView Post/Check IPPrint Post   Move Post (Moderator/Admin Only)Ban Poster IP (Moderator/Admin only)

Your 3904 should work, it is a general purpose NPN transistor.
Does the LED light up?
Does the laser light up?
Do either of them flash as you send data?
Did you connect the LED and the laser in the right direction?
Does the LED light up when you connect it between pin 5 and pin 4?
If you connect it that way, does it flash when you send data?
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Andrew P (Krazykiwi)
New member
Username: Krazykiwi

Post Number: 2
Registered: 3-2007
Posted on Wednesday, March 14, 2007 - 6:15 pm:   Edit PostDelete PostView Post/Check IPPrint Post   Move Post (Moderator/Admin Only)Ban Poster IP (Moderator/Admin only)

The LED doesn't light up. Niether does the laser. And they dont flash when I send data. And the flatened side of the LED is connected to the transistor. As far as I can figure, the laser is connected properly.
Do you mean taking the LED out of the circuit and attaching it directly to the pins?
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Simon Quellen Field (Sfield)
Senior Member
Username: Sfield

Post Number: 1661
Registered: 12-2004
Posted on Wednesday, March 14, 2007 - 6:22 pm:   Edit PostDelete PostView Post/Check IPPrint Post   Move Post (Moderator/Admin Only)Ban Poster IP (Moderator/Admin only)

You don't have to take it out of the circuit.
Just connect the end that isn't connected to a pin to the other pin.
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Andrew P (Krazykiwi)
New member
Username: Krazykiwi

Post Number: 3
Registered: 3-2007
Posted on Wednesday, March 14, 2007 - 6:32 pm:   Edit PostDelete PostView Post/Check IPPrint Post   Move Post (Moderator/Admin Only)Ban Poster IP (Moderator/Admin only)

You lost me. The end of what that isn't connected to a pin?

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