Target Time Constant Chart

[hobbes_lives]

Does anyone have available a chart that shows the time constant for various coins and/or other targets? I'm specifically curious about old silver coins, such as Spanish reales. Perhaps the TC of a silver quarter would be pretty close, but I don't know that value either.

[Tinkerer]

Target time constant

Does anyone have available a chart that shows the time constant for various coins and/or other targets? I'm specifically curious about old silver coins, such as Spanish reales. Perhaps the TC of a silver quarter would be pretty close, but I don't know that value either.

bbsailor has supplied some information about target time constants, that came originally from Eric Foster.
We have discussed the subject somewhat in the threads EDDY CURRENTS and TARGET TIME CONSTANTS.
I have not done the testing of long TC's yet, I suspect that the TX pulse length has some influence on the TC of the targets.

To find the TC of a Spanish silver 8 Reales, I think we need to setup the test circuit to be able to make a TX pulse of several hundred uS, with a "flat top" of at least 100uS. Then read the decay curve over at least 500uS.

Having this circuit setup, it will be interesting to do various tests on TX pulse lengths to observe differences.
The point in question is the influence of a prologued "flat top". This has been the cause of heated discussion on several forums, but still the opinions are much divided.

Tinkerer