What is the relationship of uH and sensitivity?

[Beach]

Hey there!

Been a while; Mostly I have been out detecting. This summer I have found 1 gold ring, a gold watch, three silver rings, silver jewelry, a lot of coins, both domestic and foreign, and last night I found 3 cans of beer buried in the sand just waiting for me to drink them.

But here is the thing….I saw an experienced detectors on the beach the other day and he was moving through it like a machine. His detector was not that much better then mine, yet he was finding things that I was missing. He has been detecting for 35 years and it was a joy to watch him operate. I learned a lot just watching him and I realized that his coil was picking up things that I miss.

So I have decided to build a different coil for my detector. Yes, I know I could just buy a better coil, but I would rather have fun building one. Which brings up my question?

Is there any relation to the uH of a coil and its sensitivity? Does a coil become more sensitive as the uH gets higher?

Any thoughts or links would be helpful.

Thanks!

[Carl-NC]

Generally, a lower L on the TX coil increases depth at the expense of power consumption. A higher L on the RX coil increases depth at the expense of bandwidth. Many detectors use tuned coils so moving them either way will hurt depth.

What detector are you using?

[kasparov747]

what is a lower L

Carl when you say a lower L on the transmit coil will help depth will more battery usage, what is meant by a lower L? Thank you for your time.

[Carl-NC]

For a given coil diameter, supply voltage, and transmit frequency (assumes sinusoid), a lower inductance increases the transmit field strength.

[Beach]

For a given coil diameter, supply voltage, and transmit frequency (assumes sinusoid), a lower inductance increases the transmit field strength.

OK, let me see if I can rap my beedie little mind around this....

If my stock transmit coil reads 100 uH and I wind one that is 90 uH, I can gain 10 percent more field strength?

[Beach]

What detector are you using?

It is a sharper Image express. The down side is that it is cheep, the up side is that it paid for itself in 5 months this summer.

The readings on the coil are Tx 2.1 uH at 7Ω. Rx 96 uH at 27Ω.

[wam]

Hi, if you would ever open it, could You post some photos from inside?
I am not sure if You get right Your uH numbers - it is a litle unusual.
Have a good fun.
Regards,

[6666]

Maybe this one

[Qiaozhi]

The readings on the coil are Tx 2.1 uH at 7Ω. Rx 96 uH at 27Ω.

Did you mean to write mH?
I don't know of any detector that uses (or can use) a TX coil of only 2.1uH.

[Beach]

Maybe this one

They might be the same ones, but mine looks a bit different...

[Beach]

Hi, if you would ever open it, could You post some photos from inside?
I am not sure if You get right Your uH numbers - it is a litle unusual.
Have a good fun.
Regards,

I am afraid to open it because I might break it. Also I ment mH not uH.

[Beach]

Did you mean to write mH?
I don't know of any detector that uses (or can use) a TX coil of only 2.1uH.

Yes I did mean mH. Thanks for the correction.

[Beach]

For a given coil diameter, supply voltage, and transmit frequency (assumes sinusoid), a lower inductance increases the transmit field strength.

OK, now I am all confused....

I have done some experimenting with magneticlly levetated pulse motors and have found the bigger coils i used (meaning more copper and turns) the faster my motors went. The asumpting being that the more copper I used the higher the inductance therefore the higher the inductance the more powerful the coil....

So how can a lower inductance increase field strength? I am getting something wrong here....What am I missing?

Thanks!

[WM6]

So I have decided to build a different coil for my detector. Yes, I know I could just buy a better coil, but I would rather have fun building one.

It is hard to buy different coils for Chinese detectors even if you wish only to replace stock one.

Detector you have is one of the better Chinese detector in its class.

It make sense to build better coil, say DD one.

Wish you all success with DIY.

[ivconic]

Yes I did mean mH. Thanks for the correction.

Seems that is "same old" machine, packed in several different packages, which usually came from different manufacturers from China.
Complete chaos there in their market! God only knows who is copying whom there!?
I had same machine with same coil data, named "Black Knight".
It is descent as start up.
I was satisfied with it's stability and Disc on mineralized soils.
Yet i was not satisfied with depths.
Coil data and some stages in machine mostly reminds me on Fisher...
So it would be good advice you to try it with some original Fisher coil.
Closest would be coil for Fisher's 1265, 1266, 1236.....
Pick one and try...
Or... DIY coil for SMW, explained somewhere on forum. Search it.