Uni-PI - Universal Pulse Induction Metal Detector board for microcontrollers like Ardiuno, PIC, AVR.

[green]

mickstv has been using a longer ground sample time than I have. Did a test today varying some of the delay and sample times with my bench circuit. Kept the Tx the same, varying it would probably effect the readings. Charted meter readings at integrator out. The longer ground sample time does increase the signal, have to try detection distance to see if signal increases more than noise, think it will. Doubling or reducing signal to half should effect detection distance about 1 inch. Changing delay time between target sample and ground sample had little effect.

[Wahyu]

Hi, Green,

what effect delay between target sample and ground sample? ,
i found at field if delay 10us - 15us, signal target not loud and clear, long TC between sort TC sometime same tone, but if delay betwen 6us - 8us, target it's loud and clear sound, and for control Ground Balance wide not touchy.
my preamp gain 150

Regards,

Wahyu

[green]

Hi, Green,

what effect delay between target sample and ground sample? ,
i found at field if delay 10us - 15us, signal target not loud and clear, long TC between sort TC sometime same tone, but if delay betwen 6us - 8us, target it's loud and clear sound, and for control Ground Balance wide not touchy.
my preamp gain 150

Regards,

Wahyu

Which sample do you adjust to cancel ground signal(first delay, target sample, second delay or ground sample)? I think adjusting either one could be used to cancel ground signal, not sure which one is best. I adjust the target sample time with the others fixed. I'm charting signal change caused by adding the target. The meter filters the noise, maybe a 1count change with or without the target. Looking at the data I think I'll stay with 4usec for the second delay. Need to repeat the top four lines varying ground sample time with target swinging on a pendulum to see if I see a change in detection distance. My preamp gain 450, integrator gain 100*sample time usec/1000usec.

I have a pot to increase first delay time if needed, maybe salt water. The shorter the first delay the higher the signal strength.

[Wahyu]

i mean , delay time between target sample and ground sample, my sample width fix 20uS, target sample, ground sample, and EF sample,
and i found effect delay target, 6us-7us its good sensitive and distance at test Air, but at ground it's bad, so adjust to around 8uS - 10uS good result, my target gold ring 22K at 20cm

[green]

i mean , delay time between target sample and ground sample, my sample width fix 20uS, target sample, ground sample, and EF sample

My error. I don't use a micro and forgot you might adjust ground sample gain to cancel ground. Increasing the second delay time would require increasing the gain of the ground sample, increased noise. Probably shouldn't have replied in this thread since I know little about micro's.

[Wahyu]

^_^ . ok , thank for reply and for share mr green.

[green]

Would adding an integrator before the A-D and using the micro to control and sample the integrator vs sampling amplifier out with the A-D be better or worse?

[Wahyu]

I,m sorry Mr. Green, i don't know about micro, my project MIMITI_PRO , just use IC analog