PSPICE Model :throw:

[hobbes_lives]

Does anyone know if there is a method to simulate an object passing a search coil in a circuit simulator, such as SPICE or PSPICE (OrCAD)? I imagine Eric Foster, Mr. Bill or another one of you electronics pros have perhaps tried something like this?

Thanks for any input!

 

[Carl-NC]

I haven't actually tried this, but if I were to try to do it, this is what I would try...

Make the RX coil part of a mutually coupled pair (M1), with the other coil being driven by a sporadic target "signal". Where would you get the target signal from? Well, you could create another mutually coupled pair (M2), with one side being the TX coil and the other side used to drive a sporadicator; that is, a circuit that takes N number of TX periods, and does amplitude (and phase, for VLF) shaping that simulates the coil passing overhead.

If you are simming a PI mono coil setup, then split the mono coil into 2 inductors, say, 90% and 10%. The 90% becomes the TX coil for M2, and the 10% is the RX coil for M1. You can further adjust the coupling factors for target strength.

Sound complicated? I think so, too. Lemme know if you get it working, then tell us how you did it!

- Carl

 

[hobbes_lives]

I am trying to simulate a PI mono coil setup. Here's what I've done.

I used a transformer in place of the search coil, with the primary side of the transformer used for the search coil and the secondary is used as the target. I set the transformer up with an inductance of 300uH for both the primary and secondary, and used 100% coupling. I placed a load resistor across the secondary side that can be changed to simulate a target. Note that a very high value resistor (I used 1000Meg) must also be placed from the secondary circuit to ground to be able to simulate the circuit.

At a high value for the load resistor (1Meg), there is no effect on the width of the pulse signal at the search coil. With a low value for the load resistor (50ohms), the pulse width is drawn out, similar to what would be expected when a target is near. I don't know if this is similar to real-life analysis, but I think it can be used for simple simulations.

Perhaps there is a better circuit to simulate real-life findings?