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LDmicro Forum - interference problems

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interference problems (by luis elizarraraz)
Thanks for your ladder. it is very good. My thread is the follow:

I tested the pic circuits for power handled, specially for ac motor controls. The problems are the resets and erratic operation caused for the power interference and noise.

I tested capacitors, suppresor diodes, vars, etc, but I canīt one solid solution.

I passed to test 2: software solution. For that reason I change my compiler and I used your LD aplicattion. The conclutions are exactly the sames: erratic and noise interference without aparent solution.

If you have any, any thing about this topic, will be welcome, because my idea is to make circuits with commercial (stable) features.

Thanks new and I hope your answer about this.

Luis Guillermo Elizarraraz
Wed Jul 28 2010, 14:06:41
(no subject) (by Jonathan Westhues)
Your problem is almost certainly not related to the firmware or development tools. If the PIC is resetting, perhaps due to glitches on its power supply or large currents injected through the protection diodes on I/O pins, then there is nothing that any compiler can do to change that.

It's not possible to comment further without seeing the schematics and layouts of your switching circuit. But in general, it's a bad idea to attempt a high-power design without a full understanding of the circuit. The result is likely to be unreliable or dangerous.

A conservative starting point might be to build the PIC circuit on a printed circuit board with a ground plane, with a low-side output driver (like an n-FET) to control a relay, and a Zener diode rated for more than the relay's operating voltage (but less than the n-FET's drain-source breakdown voltage) clamping the voltage at the drain of the n-FET.

You then could purchase an "electrician" type mechanical or optical relay, in a separate box and with appropriate isolation between the control and power wiring. Compared to high-power electronics on your own printed circuit board, this is more likely to work, to be safe, and to comply with applicable law.
Fri Jul 30 2010, 04:24:34
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