Lab -1: Burn out your AD524 Instrumentation Amplifier

In keeping with the spirit of negative numbers, you will received credit for Lab -1 by NOT doing it.

How can you burn out the 524? Most likely way: connect +Vs to - 12v and -Vs to +12 volts--reverse the power supply inputs. Notice in the pinout below that +Vs and -Vs are right next to each other... +Vs (pin 8) should go on the bottom corner, on the same side as the dimple or triangle marking pin 1.

Why do we care if you burn out a 524? Because one of them costs $17. Almost like taking a match to a 20$ bill; not quite...the twenty takes longer to burn...

What can you do to lower the probability that you will burn out your 524? #1 Ask your lab partner, "Does it look like I hooked up the circuit correctly?" Then if she answers, "Yes," and you turn on the power supply and see a puff of smoke come from the chip, you can blame her.

How can we tell if it's your 524? At the beginning of the semester we will issue you a 524 in its own socket, marked with colored-coded dots from a Sharpie.

What to do if it burns out? Throw it in the trash? No. Don't throw any "bad" chips in the trash. Give it to us and we'll put it in the transparent plastic urn of burned out chips. We can show the urn to other students and say, "Don't let this happen to you."

How can you tell if burned out the chip, if you don't have firm evidence of smoke, or reversed power supply? In fact, you probably didn't burn out the chip. You probably forgot to connect pin 6 to ground, or to strap pins 9 and 10 together, or your differential input is too great for the gain you selected. Or you didn't strap for any gain. Or you forgot to turn on the power supply, or push the Track button on the power supply. But if the chip is wired up properly for a gain of 10, and you put 500mv across pins 1 and 2, you should see 5 volts at the pins 9-10 output.

At any rate, if you really did burn out your 524, we'll issue you another one and erase our initials from your scorecard noting you no longer have credit for Lab Minus One.