Success, made PI4 from ITMD

[6666]

Today I bread boarded the PI4 and it works nicely. I used two 5 volt battery packs for spilt power supply and a 3dss coil @ 338 uH, and IRF9640, 4,700uF cap across supply,, 8 ohm speaker,,and a pretty clean signal from pre amp out, the good thing about the PI4 is it uses the + input for the pre amp and you can trim the damping resistor,(460 ohm).
I am getting about 8 inches on a large coin , and it picks up a 3 gram gold nugget, and has reasonable sensitivity.
I like the vco sound, over all I'm happy with the project.

The PI4 seems to handle the EMI well, as it kills most detectors, and interestingly there is no EFE signal when waving the coil.

[bernte_one]

congratulations,
did you made any changes at the schematic, or did it work like it is?

is it possible to make a video, i would like to hear the detection sound

[surfdetector]

I like the vco sound, over all I'm happy with the project.

I would also like to hear what the vco sounds like as well if you could do a short clip.
Cheers

[6666]

congratulations,
did you made any changes at the schematic, or did it work like it is?

is it possible to make a video, i would like to hear the detection sound

Hi , I will try and make a video, just got to find my camera.
I made the project as per the circuit in the book except for a couple of changes in parts because I used the parts in the junk box.
I used two 5 volt battery packs not the 5532 virtual earth
4,500uF cap across the supply, not 1,000
both the transistors are BC549C
the pre amp is a single ne5534, not a ne5532
IRF9640 fet
I only had a 50K pot not 100K for delay

[6666]

Video clip of bread board PI4 from ITMD, shows 3dss coil and audio with coin waved over coil, used a single 5534 for pre amp, works nice , has pre set threshold, the delay works and will detect a one gram gold nugget at about 2 inches

https://youtu.be/G6qpXoIAnyE

[surfdetector]

Very nice audio. Thank you for posting the clip.
Cheers

[WM6]

Nice relaxing voice!

[6666]

I wonder if you could use the 12f1840 as a stand alone VCO ?

[bernte_one]

maybe you can add this
https://www.geotech1.com/forums/show...ht=pulse+audio

[bernte_one]

i forget that i did pi4 in the past but i cant find any of my files

i hope someone can upload the complete itmd book files as container
codes, gerber, shematic.....

[Qiaozhi]

i hope someone can upload the complete itmd book files as container
codes, gerber, shematic.....

Please do not request copyrighted material to be uploaded to the forum.