Photo transistor with ADC

Tricky Nekro

Hello again...

I'm just confused about this... How would I be able to connect a transistor with a ADC (I'm still confused and I need help)...
The transistor only consist of an emitter and collector (the sd 1440 serries)...
Is a current liting resistor needed... And is the other input of the ADC grounded..


Thank you...
Provas, Greece...

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Chris Savage

I hope I understand what you're trying to do...Photo Transistors only have an emitter and collector.· In this case you could tie the emitter to ground and the collector to the ADC input, pulled-up by a 10K resistor.· What this would give you is an inverted reading.· What you could do it subtract the ADC value from the maximum count value.· For example, if it's an 8-bit ADC you could do 255 - ADC Reading to normalize the inverted readings.· If I lost you, the readings would be inverted in the sense that more light would give a lesser value on the ADC at the transistor pulls closer to ground.· I hope this helps.· Take care.

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Chris Savage
Parallax Tech Support

Tricky Nekro

Thanks for your reply,

Based on your advice, is this going to work...

Look down for·the .rar

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-Rule your Destiny-
--Be Good. Be Bad. Be Provas--

The hellinic (Greek) robots portal: Greekbotics
Many Projects and Schematics by the users·and also robotic news
(Translate using babelfish)

Post Edited (Provas) : 9/12/2006 7:49:09 PM GMT