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Safe Way of Detecting EMP by MCU

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Mechatrommer:
i'm currently tried to detect my camera flash light burst by picking the EMP (EMF?) using a simple inductor. directly connecting the signal to mcu (1), is working ok as the mcu is detecting it as well. but thinking EMP might not be safe for the mcu, i try to change to (2) with a transistor and resistor in between, still DSO indicating not a clear signal in, if possible.. i want to change the ocsilating spike into something smooth like in (3).. any tought?

joelby:
Clamp the signal with a diode and use an ADC input?

Comparator/Schmitt trigger?

Simon:
yea put a diode in series, maybe a capacitor in parallel after the diode and perhaps a 5V zenner diode in parallel with the MCU input

jahonen:
When I first read the subject, I thought that someone really wants to find a safe way to detect the EMP pulse due to nuclear explosion in upper atmosphere, one really does not need the MCU to detect that :P ;D

Comparator with possibly some signal conditioning before the that would make quite tweakable pulse generator to the MCU.

Regards,
Janne

saturation:
You basically want a radio tuned to the output frequency of your flash unit.

So, to build it, you need an antenna, you might want to tune it to the specific frequency you want, then amplify it enough to be useful to the input stage of the MCU.

Otherwise you want a spark gap style radio that just picks up anything and amplifies it, and you'll presume the strongest frequency that bursts is your flash unit.  If you do not tune it, it can also pick up fairly large EMF from motors and such, and just waste energy amplifying noise.

Given the voltage drop across a diode is at 0.6V or so, you need to preamp the input stage after the antenna.

The goal of the preamp stage is to get enough gain to feed the MCU.

Since you are only looking to detect a burst of  specific frequency, you can digitize the input signal in the MCU and make a digital filter to isolate the peak or make the filter an amplified band pass filter before the MCU, thus passing only the desire signal for analysis.

I see to summarize:

antenna, RF pre amp, diode, optional filter, mcu

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