Inductive signal to Arduino

Forum 2005-2010 (read only) Hardware Interfacing
#1

I want to use a coil to sense a rapid current pulse passing through a wire nearby. I hooked up the coil to oscilloscope and the following is what I see.

The amplitude can be as high as 60 volts and the period is about 25ns. The question is how can I make the signal suitable for Arduino.

I think I need to make the maximum voltage ~5 volts and lower and make a output pulse longer enough so I can pick it up with polling or with an interrupt. Can anyone recommend a circuit?

Thanks.

#2

Richard,

I only need to detect the pulse, the occurrence of the pulse. I don't need the other information.

There probably isn't much current. I think what I saw was the induced current bouncing around in the parasitic RLC circuit of the coil and the oscilloscope probe.

I didn't try LED or opto-isolator. The voltage isn't correct and perhaps the energy isn't sufficient.

Thanks.

#3

For starters I would use four diodes in a full wave rectifier with -ve connected to ground. Then from the +ve end through a series diode and series resistor (100R) to the analogue input of the arduino. In parallel to the input I would put a 1uF capacitor and a 10K resistor across that to act as a peak detector. Finally you need catcher diode (any small signal diode) from the analogue (anode) input to the +5V supply (cathode).

#4

Mike,

Were you describing a circuit like this?

What's the purpose of the diode after the full wave rectifier? 100R means 100 ohms?

Thanks.

#5