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Hey.. Can someone let me know how this circuit works?

http://www.freeimagehosting.net/4iynj
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I can see how it works, but I can't explain it.

The (-) input is kept at a voltage above the middle with the 3k3 and 10k.
The (+) input is the middle between the output and the power (perhaps 5V or 12V).

The 'set' pulls the (+) input to ground, so the (-) input is higher, resulting in a low output and the led turns on. The low output keeps the (+) input in the middle, so that is still lower than the (-) input. The output stays low.

The 'reset' make the (-) input always lower than the (+) input, so the output goes high. If the output is high, the (+) input is always higher, so the output stays high.

Does this explanation make any sense ?
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Throw it in to:
http://www.falstad.com/circuit/
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I really dont understand what you said. I can understand how, but I need to know why this is used.

http://www.falstad.com/circuit/ ...

Should I download something from here.. I dont know where to input my ckt.




{{{{{{{{{
Circuit:
http://www.freeimagehosting.net/4iynj
}}}}}}}}}}
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I really dont understand what you said. I can understand how, but I need to know why this is used.

The "why" can be due to many factors. The person deciding how to build the circuit would evaluate all those and build the circuit a particular way. One of those factors might be, "that's the parts I have on hand". Or maybe it's a circuit to demonstrate the use of a particular component. We could speculate endlessly on this. Perhaps you could supply some context?
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Quote
Can someone let me know how this circuit works?

Clue:  hysteresis
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Context..errmm.. This was designed by Alan Tyger. and its called Flip-Flop Memory Op-amp.

The op-amp has a positive feed back and I know that it has something to do with hysteresis..I tried to understand, but just cant figure out how this works..
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It's an RS latch (without a complementary output.)  http://cs.fit.edu/~wds/classes/comp-org/Logic/sequential.pdf
I don't know who Alan Tyger is, but that circuit is as old as the hills.
It'd be better to use a dedicated comparator.  A comparator can be made from an opamp, but a comparator (LM339) is better suited to the task.
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oh.. Ok.. so the link which you gave me is similar to the circuit which i posted?
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