Photoelectric trip switch required for project

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Old 12-05-15, 09:26 PM
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Photoelectric trip switch required for project

Hello forum,
All my searching was fruitless to handle what is likely an easy task for the electrically knowledgeable here.
I have a computer fan running off a 12V dc adapter with the goal of cutting its power when an object is detected within 10mm to 80mm of a sensor. But then starting up after an elective delay such as 5 seconds. And then repeating the process continually.
Thx for lamen help.
R
 
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Old 12-05-15, 09:50 PM
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Welcome to the forums.

A photoelectric switch is comprised of two parts..... a light (transmitter) and an eye (receiver) and when the beam is broken there is activation.

What you are describing is more of a motion sensor switch but to have something like that accurate from 10mm - 80mm (1/2"-3") is difficult.
 
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Old 12-05-15, 10:13 PM
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Thank you for the response which gets me thinking I best describe the project. I have a 12V computer fan creating a vacuum in a shoe box container, when a ball gets sucked up into the container I'm thinking the fan needs to stop for a few seconds so the vacuum ceases and the ball can leave the chamber via tube because it's seal relaxes... Then the fan starts up again. So the project requires a sensor to stop and a delayed before it starts again.
 
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Old 12-05-15, 10:28 PM
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Maybe a photoeye would be the way to go. The ball could block the beam and shut the fan off. You wouldn't need a delay.... the fan wouldn't restart until the ball fell and was clear of the beam.
 
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Old 12-05-15, 11:04 PM
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You might look at circuits for 555 timer chips. Outside my skill set but know enough to think that might be the direction to go. Lots of diagrams on the net.
 
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Old 12-06-15, 05:53 AM
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If the final location of the ball where the photo detector is supposed to be located is that precise, perhaps a sensitive micro switch would work?

Bud
 
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Old 12-06-15, 07:36 AM
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There should be plenty of reasonably priced photoelectric and timer boards available to build your project (Google 12V timer, etc). You may experience problems using photoelectric due to ambient light reflected off the target (ping-pong ball). Experimentation will tell.
 
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Old 12-06-15, 03:06 PM
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Thank you for the advice, I sure will check it out.
 
 

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