Finishing two 3DSS coils

[Qiaozhi]

Thanks 6666.

Hi Qiaozhi - Should I kick off a new thread in the MPP Project area to ask about how to find the R1 value for coil critical damping?

Yes, that might be a good idea.

Be aware that the diagram I posted is a general demonstration of coil damping, and not actually what you will see at the preamp output. That's because the preamp output will be driven into saturation. Also, the MPP preamp signal will initially go negative before settling down to 0V, so don't get confused by thinking that it must go positive first. The output will look different depending whether the preamp is an inverting or non-inverting configuration. I will post another diagram later to make things clearer.

[green]

Yep. That?s exactly the variable resistance rig I put into the R1 position but no amount of adjustment gave us a plot remotely resembling a critical damping curve. This is what the CRO looked like when it was detecting a set of pliers well at a distance of about a foot.

https://www.geotech1.com/forums/atta...5&d=1610967809 _______ What is the scope probe connected to? Volts/div? micro seconds/div?

[Qiaozhi]

A picture is worth a thousand words.

[Roo2]

https://www.geotech1.com/forums/atta...5&d=1610967809 _______ What is the scope probe connected to? Volts/div? micro seconds/div?

Was on 0.5V/div and 0.5mS/div for the time scale.

[Roo2]

Im expecting a DSO in the mail soon so will be interesting to see if its much different to the CRO.