IR sensor with LM324

one) (Vin) + 9V - |

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-----+-------+----------+---+----------------+--------------------------------------------- GND

Hi, Manimozhi. To start with:

1) Try just attaching the 9V supply to the piezo element. This won't kill it. But usually, beepers that have a specified DC voltage have the oscillator/driver built-in, and all you have to do is apply voltage. You might find your piezo element starts beeping when you apply DC voltage. If that's the case, the second op amp is doing exactly the wrong thing. But if you _do_ have a bare piezo element, you should be able to get much better results by bridging the drive with another 1/4 of the LM324.

2) According to your diagram, you have "IR in" as the inverting input of the first op amp. I'm assuming you've actually got a phototransistor or something like that. I'd like to know what it is, and also how you've got it hooked up. Many IR sensors require a pullup resistor to show a voltage. If you've got a meter, you can test this by just measuring the input to the op amp with the sensor in what should be the "on" and "off" states. It should change. If it's not changing, either something let the smoke out, you've hooked it up wrong, or some combination.

I'll tell you what. Answer those questions, and we can cobble together something that works for you, and put it in ASCII format for your safety and convenience.

What about the beeper -- does it beep with DC applied? What are you using for an IR sensor, and how do you have it hooked up?

Chris

OK, I'll bite: Why would an IR sensor respond to a bowl of snow? Am I missing something here?

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