SPICE Simulation Challenge

[green]

Charted the 1oz copper coin and the screw with the smaller coil to get decay out to 600us.

TX has to be 5 times greater than the higher of the target tau and the coil tau to see no more pulse width effect.Carl's reply from https://www.geotech1.com/forums/show...977#post253977

Was thinking tau is infinite with constant rate Tx. Recorded the coin, screw and a US nickel at 100us, 1ms and 10ms Tx on times. Thinking the US nickel might chart three different lines but it didn't.
The deck screw didn't chart as straight a line log-log out to 300us with the smaller coil.
Target was placed on coil and recorded at each Tx time without moving target.

[Davor]

no. don't know if bipolar Tx would improve charting target decay curve

I'm think it would. Log amplitude is very sensitive to offset. Unipolar pulses response has offset removed by means of a late EF sample, but in a case of ferrous targets that have less steep decay, their tail is knocked down by EF pulse, effectively introducing a negative offset.

[green]

I'm think it would. Log amplitude is very sensitive to offset. Unipolar pulses response has offset removed by means of a late EF sample, but in a case of ferrous targets that have less steep decay, their tail is knocked down by EF pulse, effectively introducing a negative offset.

The reason for offset to voltmeter, lower right of schematic https://www.geotech1.com/forums/atta...3&d=1556831504 adjust amplifier out to less than .5mV(no target) before recording data.

Unipolar might help if I was charting integrator out. Charting amplifier out and logout from amplifier. No EF sample.

[green]

The reason for offset to voltmeter, lower right of schematic https://www.geotech1.com/forums/atta...3&d=1556831504 adjust amplifier out to less than .5mV(no target) before recording data.

Unipolar might help if I was charting integrator out. Charting amplifier out and logout from amplifier. No EF sample.

Bipolar might help not Unipolar. Brain not working today.

[Locator]

Does anyone know the Iron time constant for pulse induction metal detector?

Thank's in advance!

[Qiaozhi]

Does anyone know the Iron time constant for pulse induction metal detector?

Thank's in advance!

A metal target's time constant depends on more than what it's made of. The time constant is also affected by the target size, shape and thickness.
Asking for the time constant of iron is like asking "How long is a piece of string?".

[waltr]

Does anyone know the Iron time constant for pulse induction metal detector?

Thank's in advance!

Like all targets it depends on the SIZE of the iron.
Smaller targets have lower TC. Example: A US silver quarter has a higher TC than a US silver Dime, even though both are the same metal.

Also, for non-round targets it depends on the orientation. A nail on end has a much different TC than on its side.

This is the main reason Discrimination can not be done by TC.

[Locator]

Thank you for your replies!