Can search coils be use for different machines? Why or Why not??

Jo ann · Sep 5, 2014

Can search coils be use for different machines? Why or Why not??
I`m trying to learn more about metal detectors, it`s not too far off that I will be upgrading, I have way outgrown my first one, I have the ace proformance coil, and hate to see it wasted, also would like to see if I would like a higher or multi frequency before spending way too much.
Sorry if this is a repeat question, I looked for the answer but couldn't find anything.
Thanks.

ohiochris · Sep 5, 2014

Unfortunately most coils wont interchange between detectors , with a few exceptions. I believe Garrett ace coils will work on any of the garrett ace detectectors but they wont work on anything else.

JoeR · Sep 5, 2014

2 reasons they don't normally interchange.
1) the connectors are different between the brands.
2) they are tuned to different frequencies. They can't be used at different frequencies for the same reason you can't use the wrong guitar spring in the wrong place..

There are probably more reasons as well.

Joe

Jo ann · Sep 5, 2014

JoeR said:
2 reasons they don't normally interchange.
1) the connectors are different between the brands.
2) they are tuned to different frequencies. They can't be used at different frequencies for the same reason you can't use the wrong guitar spring in the wrong place..

There are probably more reasons as well.

Joe

Hey Joe, thanks for that, I did notice that the ace 250, 350, and at pro will use that same coil, but those three are differant frequencies, I wish I could wrap my brain around it better.

Jo ann · Sep 5, 2014

ohiochris said:
Unfortunately most coils wont interchange between detectors , with a few exceptions. I believe Garrett ace coils will work on any of the garrett ace detectectors but they wont work on anything else.

Yep, and they do have differant frequencies.

ohiochris · Sep 5, 2014

Jo ann said:
Hey Joe, thanks for that, I did notice that the ace 250, 350, and at pro will use that same coil, but those three are differant frequencies, I wish I could wrap my brain around it better.

The 250 and 350 should use the same coil , but the at pro will not. Though it would be great if they used the same coils as the ace.

papaharley03 · Sep 6, 2014

Jo ann said:
Hey Joe, thanks for that, I did notice that the ace 250, 350, and at pro will use that same coil, but those three are differant frequencies, I wish I could wrap my brain around it better.

It's hard to grasp unless you understand electronics theory in general. Suffice it to say, there is a thing called "resonance". A circuit containing inductors (coils) and capacitors will have a resonant frequency based on the values of those components. If your detector wants to radiate a signal into the ground at 7 khz, then the search coil and associated components must have values that make the circuit 'resonate' at 7 khz. Change the windings in the coil, you change its value and thus, shift the resonant frequency of that circuit to a value other than 7 khz. Why is this important? Because the power won't all radiate out of the coil, some will be reflected back to the unit. That can damage the components and the detector won't operate very effectively, if at all.

I hope it's a lighter shade of mud now.

Papa

Big Boys Hobbies · Sep 6, 2014

JoeR said:
2 reasons they don't normally interchange.
1) the connectors are different between the brands.
2) they are tuned to different frequencies. They can't be used at different frequencies for the same reason you can't use the wrong guitar spring in the wrong place..

There are probably more reasons as well.

Joe

Great post!

Toast · Sep 6, 2014

JoeR said:
2 reasons they don't normally interchange.
1) the connectors are different between the brands.
2) they are tuned to different frequencies. They can't be used at different frequencies for the same reason you can't use the wrong guitar spring in the wrong place..

There are probably more reasons as well.

Joe

Did you mean to say "guitar string"'? Boing.

JoeR · Sep 6, 2014

Toast said:
Did you mean to say "guitar string"'? Boing.

Duh!! I'm never happy unless I'm making an idiot of myself! :lol:

You mean guitars don't have springs? I suppose they don't have shock absorbers either....

Joe

JoeR · Sep 6, 2014

Jo ann said:
Hey Joe, thanks for that, I did notice that the ace 250, 350, and at pro will use that same coil, but those three are differant frequencies, I wish I could wrap my brain around it better.

I wasn't aware that they did that....but there's LOTS of things I need to learn yet. Maybe the 250 and 350 can use the same coil because they operate at similar frequencies, and the coil they use is obviously capable of operating at a range of different ones...but probably not too wide of a range.

Joe

Surfchunker · Sep 7, 2014

whammy bars (tremolos) on guitars have springs

Rudy · Sep 7, 2014

papaharley03 said:
It's hard to grasp unless you understand electronics theory in general. Suffice it to say, there is a thing called "resonance". A circuit containing inductors (coils) and capacitors will have a resonant frequency based on the values of those components. If your detector wants to radiate a signal into the ground at 7 khz, then the search coil and associated components must have values that make the circuit 'resonate' at 7 khz. Change the windings in the coil, you change its value and thus, shift the resonant frequency of that circuit to a value other than 7 khz. Why is this important? Because the power won't all radiate out of the coil, some will be reflected back to the unit. That can damage the components and the detector won't operate very effectively, if at all.

I hope it's a lighter shade of mud now.

Papa

Papa,

Most modern VLF detectors are purposely not run at the coil's resonant frequency.

For VLF detectors with a Target ID (TID), the receive coil inductance and capacitance are picked to make sure that the phase response is on the linear part of the curve (think of a plot of phase angle versus frequency).

SeabeeRon · Sep 7, 2014

papaharley03 said:
It's hard to grasp unless you understand electronics theory in general. Suffice it to say, there is a thing called "resonance". A circuit containing inductors (coils) and capacitors will have a resonant frequency based on the values of those components. If your detector wants to radiate a signal into the ground at 7 khz, then the search coil and associated components must have values that make the circuit 'resonate' at 7 khz. Change the windings in the coil, you change its value and thus, shift the resonant frequency of that circuit to a value other than 7 khz. Why is this important? Because the power won't all radiate out of the coil, some will be reflected back to the unit. That can damage the components and the detector won't operate very effectively, if at all.

I hope it's a lighter shade of mud now.

Papa

Rudy said:
Papa,

Most modern VLF detectors are purposely not run at the coil's resonant frequency.

For VLF detectors with a Target ID (TID), the receive coil inductance and capacitance are picked to make sure that the phase response is on the linear part of the curve (think of a plot of phase angle versus frequency).

I love it when you guys start talking "dirty" like this!!

Jo ann · Sep 7, 2014

ohiochris said:
The 250 and 350 should use the same coil , but the at pro will not. Though it would be great if they used the same coils as the ace.

papaharley03 said:
It's hard to grasp unless you understand electronics theory in general. Suffice it to say, there is a thing called "resonance". A circuit containing inductors (coils) and capacitors will have a resonant frequency based on the values of those components. If your detector wants to radiate a signal into the ground at 7 khz, then the search coil and associated components must have values that make the circuit 'resonate' at 7 khz. Change the windings in the coil, you change its value and thus, shift the resonant frequency of that circuit to a value other than 7 khz. Why is this important? Because the power won't all radiate out of the coil, some will be reflected back to the unit. That can damage the components and the detector won't operate very effectively, if at all.

I hope it's a lighter shade of mud now.

Papa

TY Chris, I thought that the aces and at pro used the same double D, profomance and sniper, I find it so difficult to understand the advertisements.

JoeR said:
Duh!! I'm never happy unless I'm making an idiot of myself!

You mean guitars don't have springs? I suppose they don't have shock absorbers either....

Joe

ohiochris · Sep 7, 2014

Jo ann said:
TY Chris, I thought that the aces and at pro used the same double D, profomance and sniper, I find it so difficult to understand the advertisements.

You are welcome. The pro and ace have whats basically the same looking double D coils , though the internal circuity or wires may be different , but at the very least the connectors are completely different. That had me confused at first too since they look the same.

Rudy · Sep 7, 2014

papaharley03 said:
It's hard to grasp unless you understand electronics theory in general. Suffice it to say, there is a thing called "resonance". A circuit containing inductors (coils) and capacitors will have a resonant frequency based on the values of those components. If your detector wants to radiate a signal into the ground at 7 khz, then the search coil and associated components must have values that make the circuit 'resonate' at 7 khz. Change the windings in the coil, you change its value and thus, shift the resonant frequency of that circuit to a value other than 7 khz. Why is this important? Because the power won't all radiate out of the coil, some will be reflected back to the unit. That can damage the components and the detector won't operate very effectively, if at all.

I hope it's a lighter shade of mud now.

Papa

Rudy said:
Papa,

Most modern VLF detectors are purposely not run at the coil's resonant frequency.

For VLF detectors with a Target ID (TID), the receive coil inductance and capacitance are picked to make sure that the phase response is on the linear part of the curve (think of a plot of phase angle versus frequency).

SeabeeRon said:
I love it when you guys start talking "dirty" like this!!

Yeah, the old BFO type detectors where indeed run at resonance, but not the more modern VLF types. :lol:

papaharley03 · Sep 8, 2014

Rudy said:
Papa,

Most modern VLF detectors are purposely not run at the coil's resonant frequency.

For VLF detectors with a Target ID (TID), the receive coil inductance and capacitance are picked to make sure that the phase response is on the linear part of the curve (think of a plot of phase angle versus frequency).

Thanks for setting me straight on that. Admittedly, I am more of an RF guy. I'm going to go back and re read that paper on Minelab's site which had the most in depth detector theory I've seen yet.

In my defense, when you look at the situation superficially, it seems that detectors which run at a different frequency always require a different coil. So I presumed it had to do with resonance.

Regards,

Papa

JoeR · Sep 8, 2014

This information begs an answer to the original question then. Why not the same coil for a 3.5K machine and a 15k machine?

Joe

Rudy · Sep 9, 2014

JoeR said:
This information begs an answer to the original question then. Why not the same coil for a 3.5K machine and a 15k machine?

Joe

Because they are designed by different engineers, using different electronic circuitry, and who work for companies that have no interest in trying to define/create an electrical/mechanical standard that insures coil interchangeability.

Can search coils be use for different machines? Why or Why not??

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