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Author Topic: How does the Basic Infrared Emitter Detector Basic Circuit work?  (Read 3172 times)

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Arkboy

• Jr. Member
• Posts: 10
How does the Basic Infrared Emitter Detector Basic Circuit work?
« on: July 18, 2012, 04:54:14 PM »
I searched the site but I couldn't find a topic on this.  How does the Infrared Emitter Detector Basic Circuit actually work?
http://www.societyofrobots.com/schematics_infraredemitdet.shtml

I see the voltage going through the IR emitter and I see the voltage go through a resister then either out the Vout or the IR detector to ground.  If the detector does not see anything does its resistance go to infinity and the voltage go towards the Vout and if it does see IR its resistance drops and allows more current to flow through it and less through Vout?  Or am I missing something that would explain it?

Failure is just another excuse to keep playing with your robot.

pterrus

• Jr. Member
• Posts: 37
Re: How does the Basic Infrared Emitter Detector Basic Circuit work?
« Reply #1 on: July 18, 2012, 09:08:11 PM »
If there's no light detected, T1 acts like an open circuit and Vout goes to Vcc.

If there is light detected then Vout is pulled down to GND.

That's the theory anyway.  Make sure your detector is actually a phototransistor, not a photodiode, or you'll need a different circuit.

Soeren

• Supreme Robot
• Posts: 4,672
Re: How does the Basic Infrared Emitter Detector Basic Circuit work?
« Reply #2 on: July 19, 2012, 09:07:42 AM »
Hi,

I searched the site but I couldn't find a topic on this.
Strange, it's one of the circuits I have explained lots of time.

I see the voltage going through the IR emitter and I see the voltage go through a resister then either out the Vout or the IR detector to ground.  If the detector does not see anything does its resistance go to infinity and the voltage go towards the Vout and if it does see IR its resistance drops and allows more current to flow through it and less through Vout?  Or am I missing something that would explain it?

Nope, sounds like you've got it
Regards,
Søren

A rather fast and fairly heavy robot with quite large wheels needs what? A lot of power?
Engineering is based on numbers - not adjectives

• Jr. Member
• Posts: 10