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SparkFun Electronics will be closed on July 3rd, 2015 in observance of Independence Day. Any orders placed after 2:00pm MT on July 2nd will be shipped out after the weekend. Thanks!

squircle

Member Since: January 13, 2012

Country: United States

  • Hello- This works very well for an encoder wheel with laser printed 1/8 marks. I have it about 1/8 inch away with the sensor oriented so that the mark crosses the emmiter and detector at the same time. I have a 220ohm resistor on the LED for 5V, (you could go as low as 100) and a 4.7k pullup resistor on the output. I have output with emmitter to ground, collector to the arduino pin, and 4.7k from the arduino pin to 5V. You can play with the resistor values to change the sensitivity. Also if you need to you can use a 74LS14 to clean up the output or use a 2n2222 to make a darlington pair on the output and increase sensitivity but you should not have to. You may have too many marks or they may be too small, in which case you have to be right against the paper. If you need to be further away make your marks wider. Oh, and it has a ‘sunlight filter’ but it really works best if you block room light. If you can cover your sense area to keep out light it works much better.

    I love this thing, it works great!

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