Tweet
Yes, these things actually do seem to work, once I was able to correct all my stupid mistakes.
Right now I have an upackaged PCB board, built up as Option 1, hooked up to a 10.25" coil. Upon power-up, it air-tested a penny at 6.5". It has NOT been tweaked or tuned to any extent, so perhaps it's just dumb luck. The thing is probably woefully out of tune.
I can tell you that I set the frequency at 1 KHz, and the pulse width at around 20 uSec. The other settings?? I haven't a clue at this point, but eventually I'll sort them out.
Two things I noted so far. First, the 16 Ohm speaker wasn't very loud. Perhaps that's due to my use of a slightly abused transistor to drive it. Second, I found that the thing was MORE stable when the pinpoint mode was engaged than without. It seemed real rock solid. But maybe that's just the bad tuning it is currently suffering with.
All in all, it seems like a nice unit with a lot of potential to tune for specific targets.
Say Carl..... it would be real helpful if you could add additional info to your writeup in regards to tuning the thing with an oscilloscope. You did a bit of that already and it was great, but I wouldn't mind seeing some more, especially in the later stages of the circuit. Nice job....
Right now I have an upackaged PCB board, built up as Option 1, hooked up to a 10.25" coil. Upon power-up, it air-tested a penny at 6.5". It has NOT been tweaked or tuned to any extent, so perhaps it's just dumb luck. The thing is probably woefully out of tune.
I can tell you that I set the frequency at 1 KHz, and the pulse width at around 20 uSec. The other settings?? I haven't a clue at this point, but eventually I'll sort them out.
Two things I noted so far. First, the 16 Ohm speaker wasn't very loud. Perhaps that's due to my use of a slightly abused transistor to drive it. Second, I found that the thing was MORE stable when the pinpoint mode was engaged than without. It seemed real rock solid. But maybe that's just the bad tuning it is currently suffering with.
All in all, it seems like a nice unit with a lot of potential to tune for specific targets.
Say Carl..... it would be real helpful if you could add additional info to your writeup in regards to tuning the thing with an oscilloscope. You did a bit of that already and it was great, but I wouldn't mind seeing some more, especially in the later stages of the circuit. Nice job....