Tweet
I'm designing a PI detector for coins and relics (no nuggets). I'm sampling at 50us so I haven't spent much time working to create a super fast coil. Air tests on a US quarter have been between 7" and 9" using brute force methods (high current, etc.). I think this sounds pretty low and I'm looking for ways to increase depth.
The question is, just how important is coil construction when it comes to depth for this type of application? I know that proper coil construction is critical for gold nuggets and smaller items where you want to sample at 15us and below. But this is a coin machine. What kind of depth increase could I expect by tweaking my coil's parameters? Could I double depth or would I only expect something like a 10% increase?
My current coil is a 10" monocoil with 20 turns of 24awg stranded speaker wire. The jacket is probably PVC. I have not shielded the coil as I've read that it probably isn't that necessary for such a long sampling delay.
Should I be looking to improve my coil or should I concentrate on other areas of the circuit to improve performance? I'm looking to increase depth by concentrating on "low hanging fruit" first. Getting a 10% increase in depth by spending significantly more time and money on a coil does not appeal to me. But doubling depth through improved coil design would be worthwhile. What have you found in your own coil experiments? Have you been able to make drastic increases in depth through improved coil design or is there a point of diminishing returns?
The question is, just how important is coil construction when it comes to depth for this type of application? I know that proper coil construction is critical for gold nuggets and smaller items where you want to sample at 15us and below. But this is a coin machine. What kind of depth increase could I expect by tweaking my coil's parameters? Could I double depth or would I only expect something like a 10% increase?
My current coil is a 10" monocoil with 20 turns of 24awg stranded speaker wire. The jacket is probably PVC. I have not shielded the coil as I've read that it probably isn't that necessary for such a long sampling delay.
Should I be looking to improve my coil or should I concentrate on other areas of the circuit to improve performance? I'm looking to increase depth by concentrating on "low hanging fruit" first. Getting a 10% increase in depth by spending significantly more time and money on a coil does not appeal to me. But doubling depth through improved coil design would be worthwhile. What have you found in your own coil experiments? Have you been able to make drastic increases in depth through improved coil design or is there a point of diminishing returns?
...Do not excpect sensitivity out of this design...better stick with an the old integrator and analog switch design.
Comment