Red and green LED's circuit

adams

Oct 19, 2013
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Oct 19, 2013
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2
Hi All,
Can you help me with this circuit?
I want to design a circuit that includes 12V Bulb, red and green LED's. When the bulb is lit I want green LED only to light as well. When the bulb is blown (current not flowing throuh it) I want red LED to light only.
Thank you for any suggestions.
 
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KrisBlueNZ

Sadly passed away in 2015
Nov 28, 2011
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What is the power or current rating of the light bulb?

Are you using a 12V DC supply?
 

adams

Oct 19, 2013
2
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Oct 19, 2013
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DC. 12V battery or 2 if required.
5W Bulb.

I am working on the project for college. It is an assembly machine for bulb 501 to push fit to bulb holder. One of the station of that design will test the bulb if its working properly. I want to connect it to the plc through a relay and if its ok dump it to one box, if it is blown dump it to reject box.

Would look nice if on top of that station I would have two LED's red and green to indicate wheter the bulb is OK or not.
 
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(*steve*)

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Jan 21, 2010
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OK, so you don't actually need the lamp to light.

All you want to know is if it's blown or not.

That's an easier problem.

This would be my first solution:

attachment.php


However, when I looked at this I realized that a far simpler solution is:

attachment.php


Note that neither circuit can distinguish between a working and a shorted bulb.
 

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