Moderator: Jeff Kinzli

First Task: Measure Inductances, Etc.

Jeff Kinzli
Advanced Member
Jeff Kinzli
Advanced Member
Joined: May 14th, 2005, 2:43 am

April 11th, 2007, 11:25 pm #1

So, the first task in building your probe is you need a target for your probe to roughly match the production coils.

Depending on detector, some use the resistance, resonance, or a combination of both to complete the transmitter circuit. So, regardless of what detector you have, it's a good idea to measure your current coil, and model your probe after that.

So, measure the inductance, capacitance and resistance of your current transmit (TX) coil.

Then, get the ferrite rod you ordered, and begin wrapping turns of wire on the center of it until you get close to what the stock coil parameters are. You will not likely be able to match all of the values, but shoot for resistance first, then inductance. Don't worry about how much capacitance your probe TX coil shows at this point.

You will want to place your oscilloscope across the TX and note the waveform, and compare it to the waveform that you observe when transmitting into the stock coil. If your resistance and/or inductance values are off, you'll likely see a malformed wave. This means not only is the TX operating under stress, but also either inefficiently or it might not work at all (when combined with the RX coils).

Again, depending on machine, you'll see different types of waveforms. Some are nice clean sine waves (like Whites single-freq machines), while others are square waves (Minelab) or sawtooths.

So, that's your project now...wind the TX coils and see what you get.

Again, depending on detector, you might get 15 turns, or you might need 100 turns on the ferrite before you get in the ballpark...


My So-called Hobbies:
Metal Detecting Cars
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Jeff Kinzli
Advanced Member
Jeff Kinzli
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Joined: May 14th, 2005, 2:43 am

May 1st, 2007, 9:48 pm #2

Anyone home? :babies:
My So-called Hobbies:
Metal Detecting Cars
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Rudy
GMOAP
Joined: May 14th, 2005, 11:27 pm

May 2nd, 2007, 1:39 am #3

Hey Jeff,

I once knew a guy named Henry. :dude:

He wouldn't give me admittance into Kirchoff's park. :ph43r:

So I pulled a Siemens on him. :spaz: :quack:

:bow:

MXT, HH Wader



Sometime I wake up grumpy, other times I let her sleep.
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AmadorAl
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AmadorAl
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Joined: May 14th, 2005, 4:55 pm

May 2nd, 2007, 3:20 am #4



Nothing personal here Jeff, but I think you may be expecting too much from us MDers here.

Now if you want to tell everyone how many HP that blown Chevy of yours has, that might be easier to follow. BTW, what kind of ET and MPH can that Chevy do in a quarter mile? Can it keep up with the mopars out there?
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