OP-Amps smoking! Getting Zapped by static electricity

metron9

I am using an op-amp TLC272CP for project. It drives the gate of an IRF510 Mosfet and that sources 16volts through LED's to ground.

The circuit works fine up untill I walk around the carpet and touch the device that holds the board at some point and just smokes.

The power supply I am using is not grounded, I am using 2 radioshack multi voltage wall warts both at 9V to give me 18V (regulated warts)

Two diodes in series drop the voltage to the op-amp


Any suggestions, perhaps a different op-amp and is the fact that the warts are not grounded the most likely problem if indeed it is getting zapped by ESD?

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Think outside the BOX!

LoopyByteloose

Walking around on a carpet and then touching implies 20-30,000 volts of electricity are zapping your Fet gates -- not good as they will self destruct.

On the other hand, you may have not zapped them, but have released a charge into the board that causes some FETs to go into a 'solenoid lock' mode. If that is the case, reseting from a power down will likely return the system to normal.

Reguarding a better power supply, it might help you gain clairity on the problem. If you purchase an appropriate switcher, it would have a ground to earth as well as substantial filtering. Wall warts come is so many grades and they all look similar except some have labels that specify that they are 'digital equipment grade'. Still they are little black boxes.

You could create your own ground, and you could add in a CORCOM powerline filter. But building all that may just be an exercise in frustration as a 'proven' power supply will give you years of satisfaction by eliminating many doubts.

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"When all think alike, no one is thinking very much.' - Walter Lippmann (1889-1974)

······································································ Warm regards,····· G. Herzog [noparse][[/noparse]·黃鶴 ]·in Taiwan