Author Topic: USB IR pen  (Read 8342 times)

Offline ae804

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on: January 27, 2008, 11:38:42 AM
Just an idea--USB provides a +5 and GND(+0) line through the specifications.  Couldn't we make an IR pen using those power lines to turn the pen on.  It'd be a lot more compact than a AA battery(or two AA batteries).

Just a thought.  The circuit would be very easy.

+5->(about)220 ohm resistor->IR LED->GND

Any thoughts?



Offline ZaPPZion

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Reply #1 on: January 27, 2008, 05:12:08 PM
IR-LED's go up to 100mA, so you'd need a 35 ohm resistor;)
(5V-1.5V (IR LED)) / 0.1A = 35 ohm



Offline bradjudy

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Reply #2 on: January 27, 2008, 05:15:54 PM
This is mentioned on Johnny Lee's page and I think he's using USB powered pens in his videos. 



Offline ae804

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Reply #3 on: January 27, 2008, 11:42:50 PM
Ah--well, I didn't know what the current was... and I hadn't seen any mention of USB pens, so I figured I'd throw the idea out.  The batteries I've seen on a lot of the pens on here seem to be a large eye sore (at least to me)

Well, sounds like it's not new news



Offline Helza

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Reply #4 on: January 28, 2008, 05:46:27 AM
Why would you want to "wire" your wireless IR pen



Offline ZaPPZion

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Reply #5 on: January 28, 2008, 06:50:46 AM
i wired mine as well, so i dont have to do stuff with the battery's :)
(and the battery's didnt fit into my pen, next one they will though)