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Does This Circuit Destroy an Op Amp
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eev_carl:
Hi,

I pulled this schematic from "Op Amp Circuits: Simulations and Experiments" by Sid Antoch.  I replicated the results with an LT Spice simulation but when I breadboarded this with a 14588, I noticed that my current protection kicked in after about a minute.  Two chips seemed to respond ok initially in terms of current and voltage.  However, they both started pulling in 150mA which is my power supply cap.  I watched this happen to two ICS.

Do I need a current limiting resistor on the V+ for this to work?  I verified each of the three voltages (-10,10,5) from the power supply with a DMM.

Thanks,
Carl
T3sl4co1l:
Did you forget bypass caps?

Tim
eev_carl:
I didn't have any on.  Should I put a pair of ceramic 0.1uF ones on V+ / GND and V- / GnD?
T3sl4co1l:
Yes, or 10uF electrolytic, or both is even better.

You should probably pay attention, to when things are getting... hot, and smelly and burned. ;)  It sounds like the chip was, I assume oscillating (without an oscilloscope, it's not easy to prove), causing excess current draw, causing it to heat up.  Eventually it got past maximum temp rating and failed shorted.

Tim
capt bullshot:
Did you turn on the 5V last?
If you apply a low impedance voltage source to the Op Amp inputs without the supply voltage you might damage the IC. A series resistor to the + input isn't necessary in theory, but helpful in practice (1k ... 10k should do the job here).

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