Measuring time

[RobN]

At what point do you measure the speed of the coil? Is it at the arrows as I indicated?
Old Surf PI kit I found in one of my boxes of junk. It was missing some parts but got it all together and seems to be working fine at first try.

[Polymer]

Hmmm, interesting question I hadn't thought about yet.

So far I've measured up to the point where the yellow line hits the zero on the y-axis.

The delay I adjust earlier on the curvy bit, in your picture that would be around 15-18us.
It works for me, but maybe could be done better ...

Hope some more knowledgable people give their take on this. Would like to know too.

[RobN]

Everybody talks about a fast coil and I just want to know at what point in the dip or wave they measure it. This is a flat spiral coil made with speaker wire and was trying to figure out how it is performing. And if anybody wants to look at my scope picture and give me comments how the surf PI is working I would very much appreciate it .

[waltr]

In my limited experience with PI MDs the time of Arrows in the scope picture are dependent on the Pre-amp Recovery more than the coil speed.
Do try two different coils and see if the time of Pre-amp recovery changes.

The only way I have been able to get faster pre-amp recovery (using same pre-amp circuit) is using an IB coil.
See my thread in the HH II sub-forum for discussion and scope captures.