Whites Surf PI schematic

[Mustafa]

Quote from Mr. Bill:
"...
Pulse delay of mentioned units:
Surfmaster PI,: around 22uS. to 24uS. Depending on who, and when it was set up.
Surfmaster PI Pro.: It should be at 15uS. Not certain it quite makes it to this, with factory adjustments.
Judging from the performance from the Garrett MK II, I would say between 18uS., and 22uS. The Tesoro isn’t any faster.
The Headhunter PI.: Specs. call for 15uS. "

Would someone please explain how does the result 22uS - 24uS calculated from schematic.
Regards,
Mustafa.

[cordius]

Surf data:

[Mustafa]

Thanks cordius, but these are transmit pulse rate and transmit pulse width.
I have no problem understanding the 555 part.
I want to learn how integrator sample delay and secondary integrator sample delay achieved using 4093.

[Mustafa]

Hi,
I am working on replacing timing logic with PIC12F675/683 on Surf PI like Carl's Hammerhead II.
I have all of the components to build except P-channel mosfet.
So I changed the coil driver for IRF740 but I am confused.
Is this coil driver works?

[1843]

Hi,
I am working on replacing timing logic with PIC12F675/683 on Surf PI like Carl's Hammerhead II.
I have all of the components to build except P-channel mosfet.
So I changed the coil driver for IRF740 but I am confused.
Is this coil driver works?

It won't work. Try to use a PNP transistor like MJ2955 instead of IRF740.

[Noemio]

Q1 is always turned ON!

[Mustafa]

Thanks 1843.
IRF9640 is in my shopping list.
I am trying to learn by modifying simple designs.
Best regards,
Mustafa.

[Mustafa]

Are these settings meaningful for Surf PI?

Main Sampling Delay 50us - 120us
Secondary Sampling Delay +165us - +235us

[kuraja]

HI!

This is my Surfmaster PI. Coil 18 cm detects coin 2.5 cm at 25 cm in air. It has transparent coil head for easy pinpointing. Drawback is I find a lot of pulltabs, nails...but also some coins too!
I also have a very cool housing design for TGSL. Something you can assemble in a quick step and pack it up in a backpack!

[cordius]

Good work Kuraja
This is my final version of surfmaster.
There is only one pot tresh
the disc pot is setting onbord trimmer R25 50K and bridge 100K pot for full performance.
Coil is 20 cm diameter.

[kuraja]

Excellent work friend!!!! I like it!

[Qiaozhi]

Good work Kuraja
This is my final version of surfmaster.
There is only one pot tresh
the disc pot is setting onbord trimmer R25 50K and bridge 100K pot for full performance.
Coil is 20 cm diameter.

Where did you get the stem and the search coil housing?
Is this something you bought separately, or did you use an old detector as parts?

[cordius]

hallo Qiaozhi,
i buy house coil and stem on italian electronics-kit site.
excuse my english.

[Qiaozhi]

hallo Qiaozhi,
i buy house coil and stem on italian electronics-kit site.
excuse my english.

Do you have a link to the site?

[cordius]

Yes, i write it on private