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Offline ramTopic starter
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« on: October 17, 2010, 12:35:23 am »
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hello wizzards, i have a little question with regards to pi md,

what is the best transmitter to be used in pi md that could penetrate the ground deeper.
1. multi frequency transmitter?
2. single frequency transmitter?

regards, ram,

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Offline GoldDigger1950
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« Reply #1 on: October 17, 2010, 03:24:46 am »
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Good question and the answer is multi-frequency but with reservations. The reason is that the coil is tuned to the frequency so you will have to have a way to make it work with many frequencies. This is going to require an active circuit in the coil which changes the overall circuit impedance to match the frequency you have selected. If you have 10 frequencies, you will have to have 10 matching impedance circuits. The coil will be a fixed value but you could use different capacitors and resistors in the circuit and switch them with solid state relays to give you the matches you need.

A complex problem for you, mate. Good luck.

You already know why the use of many frequencies is good so I won't go into that for you but for others who are reading this in passing. The conditions under which we hunt is always a variable we cannot possibly predict. Using a frequency compatible with the area in which we find ourselves increases the odds in our favor. Even in a small patch of ground we can find varying conditions so being able to switch to another frequency is very advantageous.

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« Reply #2 on: October 17, 2010, 04:56:46 am »
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thank you gd1950, a very valuable information you gave to me..so..i know w/c is the best.
thank you very much for the info,


regards, ram,

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« Reply #3 on: November 09, 2010, 07:59:56 pm »
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a very BIG THANKS !! to you GD1950 because of your very valuable explanations about coil i can design now a maching coil for dp metal detector big or small coil in single frequency transmitter! i have to study deeper the multi frequency matching circuits for automatic tuner.

GD 1950!!! thank you ! thank you ! thank you!

regards, ram,

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« Reply #4 on: November 09, 2010, 09:37:39 pm »
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Cornelius is MIA!

Problems with the PI is the hearing time,

You Pulse, You listen.

If you try to do the same during multi times you run short on time.

I don't see where you gain much by doing two time sets and samples between the two.

You may gain some Ground balance between the two, you may obtain some differential info between the two but you not going to get any more depth.

Whites and Garrett uses two time samples (Differential On Amp) to take a average and looses some noise, and jitter.

The Dual Field, I have no Idea about.   They must be taking a sample after the first , but when?


They could be running two independent detectors and linked?
 

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« Reply #5 on: November 09, 2010, 11:22:32 pm »
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hello homfire, i was confused to your explanation, i really understand the you pulse,you listen  rx/tx timings in pi. i built and tested now the multi frequency transmitter in delta pulse w/c i checked and read in zeitnitz oscilloscope, the transmitter i built is transmitting a frequency from 100hz to 6khz back and forth, the result is working well it detects different kinds of metal and depth, so i concluded that if the metal is detected it was the correct frequency for the metal to create exact eddy current. now the problem i maybe encountered is the coil, it was designed for 100hz but now transmitting 100hz to 6khz. in 100hz it will yield 50watt power output but in other frequency maybe lesser. so, i should design the auto tuner, if i could, one thing iv'e noticed to multi frequency transmitter it automatically select the ground condition to detect the metal under. gd1950 explanations were real now,except the tuner.

regards, ram,

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« Reply #6 on: August 13, 2011, 01:03:12 pm »
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the best ferekansi 135 HZ for deep

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