Electronic – How to limit current of an AC signal

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For my project, I'm trying to work with the principle of electrovibration. This principle is about simulating textures using low current electricity on an insulated conductive surface (see Wikipedia).

In order to do this, I will be experimenting with generated AC signals of 80 to 160 Vpp at 60Hz to 400Hz. I will do this by using an DC – AC converter, usually used for EL lamp applications.

My only concern is how to limit the current coming from the converter. Are the techniques for limiting AC current the same as DC, by using a simple resistor? Or is it, as I expect, more complex?

I need to limit the current to 0.5mA, for safety reasons.

Best Answer

First, you say the conductive surface will have insulation over it. That will limit the current by itself.

If you want to additionally limit current in case this insulation is removed or circumvented somehow, put a resistor in series with the voltage source. No, it's basically the same as with DC.

You say the highest voltage is 160 Vpp, which is 80 V peak, which is 57 V RMS if the waveshape is a sine. By Ohms law, 57 V / 500 µA = 114 kΩ. The common value of 120 kΩ should be fine.