Comparator LED circuit

Thread Starter

frisbee4all

Joined Feb 22, 2009
13
Question: Using an open-collector output comparator, draw a circuit that could be used to turn on an LED when an input voltage exceeds 5V.

So far I just have a capacitor in series with a reverse-biased LED...I'm just not sure which direction the LED is supposed to be in.

Thats all the information they give you in the Question, and there are no additional images. I'm not sure if they want the values for each circuit element but I'm pretty sure they do. I just don't know where to start for the calculations. Any help?
 

Thav

Joined Oct 13, 2009
82
I'm not sure why you would have a capacitor in series with an LED. Where is your comparator? It will help if you draw a schematic so we can help guide you rather than just give you the answer.
 

Thread Starter

frisbee4all

Joined Feb 22, 2009
13
I'm just rewriting the question as it is given. There are no example images in the book. All the question says is what I typed in above. So I'm assuming its just two voltage sources, one connected to the + terminal and the other to the - terminal of an ideal op-amp with a voltage out terminal...
 
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