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Followup:MOSFET Turning ON

Actually the did not blow up as we found it is working correctly when the gate source is supplied with a DC source of 8V. Let me come out with the problem more specifically. I am actually need to sense a current of 50 mA through a CT. My requirement is that if the CT responds to a current of 50 mA, the MOSFET should operate. Since the output voltage from CT is very low I went for an Voltage Amplifier. I gave the output of the amplifier to MOSFET. The output of the Amplifier was 16V peak to peak pulsating DC filtered using an electrolytic capacitor. I saw that the MOSFET did not turn ON when the amplified signal was fed. But it worked perfectly when I just checked with a 8V DC source. I think I am bit clear now?

Reply to
vijayn
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I assume here that CT means current transformer - that particular acronym has too many meanings.

Your voltage amplifier isn't an open drain/collector output is it? If so you'll need a pull up resistor in there. How is the cap connected? It should probably be wired across the output and a voltage rail - you don't want it in series with the output. What MOSFET was it again? I know you said that earlier but you've started a new thread now which makes it difficult to refer back to your original post.

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Andrew Smallshaw
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Reply to
Andrew Smallshaw

A simple circuit as an image on some web space or an ASCII text circuit would give people more idea as we have no idea what else is in the circuit.

We have no idea of the DC offset of "16V peak to peak pulsating DC" with respect to the pins of the FET, or even if all parts of the circuit are refeneced to the same ground.

We have no idea how you are applying the 8V DC source in particular where the DC source ground is relative to pins of the FET

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Paul Carpenter          | paul@pcserviceselectronics.co.uk
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Paul Carpenter

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