Bigger coil for Surfmaster ¿?

[solmer2]

Hi, I'm finishing my surfmaster PI and wonder if I can use another coil apart of the standar one. Using a coil calculator program I've checked the suggested coil (0.5mm thick. 23cm diameter 20 turns) and it gives me an inductance of 0.282 mH. I need to know if I can use another coil (bigger) if it gives me the same inductance.

Thanks in advance for the info.

[hobbes_lives]

Yes, a larger coil will work fine, so long as you match the resistance and inductance, shield it properly, and keep the capacitance low.

I built an 11" coil for my Surf PI Pro, and it works very well. Note that with a larger coil, there will be more response from the wet sand and waves if you use it at a saltwater beach. The depth on coin-sized objects is better, though.

[solmer2]

Thanks for the info.

Hi hobbes Thank you so much for the info. I'll start building a 11" coil and try how depth can it go.

[bernte_one]

Yes, a larger coil will work fine, so long as you match the resistance and inductance, shield it properly, and keep the capacitance low.

I built an 11" coil for my Surf PI Pro, and it works very well. Note that with a larger coil, there will be more response from the wet sand and waves if you use it at a saltwater beach. The depth on coin-sized objects is better, though.

can you post or link some pictures of your coil with datas
i would be helpful to improve my surf pi thx

[hobbes_lives]

Here are some pics of my Surf PI Pro. I used an 11" Hays Electronics coil housing, which he doesn't list on his website any longer. I built the coil following bbsailor's fast coil article. Just match the specs for the original Surf PI coil, 230uH, 1.37 ohms, and you should be good to go.

[Micheal]

Hi hobbes_lives .....Is this the dual field model surf pi or the previous model?
Also what kind of improvements have you seen with this coil....Can you please share with us the details ....


I have the dual field and am looking at making a 10"mono coil ....

The other thing is I have tried the 950 coil from the earlier model but it didnt work too good in the water I was getting too much chatter...So put the original back on .

[hobbes_lives]

It's a Surf PI Pro, the predecessor to the Dual Field. The larger coil provides more depth on rings and coin-sized objects than the stock 9.5" coil, however, it also picks up more interference from wave action in the surf.

I had a chance to use a Dual Field in the surf for a couple of hours some time ago. The Dual Field definitely seemed quieter than the Surf PI Pro. Whether it's due to the new coil configuration, or due to modifications that Whites made to the circuitry, I don't know. I didn't get to use it long enough to really get a sense of whether the machine is more or less sensitive to coin-sized objects, so I can't provide much more feedback on that point.

[mario]

Hi, this Surfmaster PI detector seems to be very popular on this forum.

Would you mind sharing with us depth ranges with your 11" coil.

thanks in advance

[hobbes_lives]

I've done several other modifications to the machine, aside from adding the 11" coil. With that being said, the last test I did, I was able to detect a nickel at approximately 13". That was an air test.

[mario]

Thank you for your honesty. That is a very respectable depth. I've noticed that with my SD2100V2, the depth increases in relation to coil size. In other words, I'm expecting an inch+ increase for every inch gained in coil size, which I always found interesting (coming from VLF, I never expected these gains in increasing coil size)

Also, for comparison, I'm getting a similar range. I'm constantly dissecting my unit so can not air test at the moment. However, my expected range on a nickel is around 11"-12".

The exception is ferrous. I have dug bottle caps and bronze scraps deeper.

Anyways, happy hunting and good luck on your modding.

[bernte_one]

I've done several other modifications to the machine, aside from adding the 11" coil. With that being said, the last test I did, I was able to detect a nickel at approximately 13". That was an air test.

I want an evidence !!! Cant believe it.

[hobbes_lives]

I want an evidence !!! Cant believe it.

I'm not sure how I can provide evidence for you. I just retested it under non-ideal conditions (indoors under fluorescent lights with lots of large metal nearby) and am getting 11-12" on a nickel in those conditions. I guarantee it will get 13" in a quiet area. I usually test and calibrate in the middle of my back yard where there's much less noise.

[bernte_one]

post a video(link)

if i go in my backyard to test the surf pi my neighbors think it try to test a gamma ray weapon (old people)

[Vortxrex]

Thank You Hobbes Lives

I am in the middle of my Surfmaster project & I am going to build an 11 inch coil as well as several other sizes to play around with. Thanks Andy, APBerg & EVERYONE who has shared all the great info.

Dave Frank

[hobbes_lives]

post a video(link)

Perhaps I will next time I'm out there working on it.

if i go in my backyard to test the surf pi my neighbors think it try to test a gamma ray weapon (old people)

My neighbors must wonder what the heck I'm doing too. I've been out in the middle of my back yard several times with the Surf PI and an oscilloscope.