Pin-pointer metal detector front end not working. Answered
I breadboarded the pin-pointer metal detector and am having trouble with the front end. pcounterA reads 11-14 on the serial port monitor.
See previous question on instructibles reproduced below:
Asked by jont4e 2 days ago
Hi, I bread-boarded your circuit for just the end coils to start, and loaded the sketch. It seems to be pulsing the coil OK but the leds aren't responding nor the buzzer. I uncommented the serial port code and it shows ledthreshold1 always at .97, pcounterA at 12, and calav1 at 81. Is this OK? (The other reported variables are always 1000.) I wound the end coils with some bifilar wire I reclaimed from a microwave HV supply transformer. I assumed that was OK? Do you have a flow chart or description of how the code works so I can troubleshoot? Any help or hints would be greatly appreciated. Jon T
Answer from TechKiwi... 2 days ago
The pcounterA value should be much higher 200 to 800 at least. My advice is to focus on one channel. Try reversing the polarity of one of the coils as this often is the problem as the pulseIn function needs to have a clean leading edge to trigger the timing process. Ensure your breadboard connections to the coil are short and well grounded. If this does not work direct message me with a link to some photos of your setup and I will try to assist. I'm just building a second unit so your timing is fortuitous as I can provide some test measurements.
Attached are images of the front end scope traces and a shot of the breadboard. Coils are off screen to the left.
Swapping coil polarity did not seem to change any waveforms.
Hope someone has some suggestions I can try.