HAMMERHEAD REV D PROBLEM

[kt315]

Hello
Dear Qiaozhi
I have built HH1 Rev. C and and tested it with GPX 11" coil. I tested its damping resistor and reached to 10K. But my sensitivity still is very low. Do you think there is any tip to do for reaching high sens like TDI? I opened TDI and see that it also has used 1K for RX coil. Is any one succeed to use GPX coil over HH1 with high sensitivity?!

the tester was done for searching of unknown coils. ESPECIALY PROJECTED FOR GEOTECHERS -!!!
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this is MY HELP, if you need help. asking me in email - for what??? i can answer you here!

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[h9361]

Thanks for your replying.
I tested damping resistor tool provides a range between 181R and 1672R, but my result still very weak. For example, i can detect a Nickel coin from 4cm not more!

[Qiaozhi]

Thanks for your replying.
I tested damping resistor tool provides a range between 181R and 1672R, but my result still very weak. For example, i can detect a Nickel coin from 4cm not more!

You've created an extra problem by posting the same question in three different places.
I replied in one of the other threads.

[h9361]

OK, please forgive me dear Qiaozhi.
As you know, HH1 is working in 900-2300 Hz. TDI also is working in 2.6 - 3 KHz.
Since GPX coils easily works over TDI, do you think i should change HH1 range frequency to TDI range?!

[kt315]

HH1 is working in 900-2300 Hz. TDI also is working in 2.6 - 3 KHz.
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you have to learn PULSE INDUCTION principle. NOW!

[green]

Thanks for your replying.
I tested damping resistor tool provides a range between 181R and 1672R, but my result still very weak. For example, i can detect a Nickel coin from 4cm not more!

If your Nickel coin is a US Nickel with a 11 inch coil you have a major problem. Target signal is effected by Tx coil peak current, turns, wave shape, Tx on time and maybe others. A US Nickel has about 10us TC so not effected by Tx on time greater than 40 or 50us. That leaves peak current and Tx turns. After Tx comes Rx, signal to noise ratio. Doubling signal to noise should increase detection distance maybe 4.5cm. I'm guessing the detector should detect the Nickel at around 40cm. No guess why detection is so low. Increasing sample delay 7us would halve the signal, maybe a 60 to 70us delay would come close to what you are seeing.

Including a couple charts I posted awhile back with US Nickel and Quarter targets. Three minor lines on chart doubles or halves the signal.

[Qiaozhi]

OK, please forgive me dear Qiaozhi.
As you know, HH1 is working in 900-2300 Hz. TDI also is working in 2.6 - 3 KHz.
Since GPX coils easily works over TDI, do you think i should change HH1 range frequency to TDI range?!

Changing the TX pulse rate will not make a difference. Crossbow (HH variant) runs at 1000pps, and worked just fine with the Minelab coils.

[green]

If your Nickel coin is a US Nickel with a 11 inch coil you have a major problem. Target signal is effected by Tx coil peak current, turns, wave shape, Tx on time and maybe others. A US Nickel has about 10us TC so not effected by Tx on time greater than 40 or 50us. That leaves peak current and Tx turns. After Tx comes Rx, signal to noise ratio. Doubling signal to noise should increase detection distance maybe 4.5cm. I'm guessing the detector should detect the Nickel at around 40cm. No guess why detection is so low. Increasing sample delay 7us would halve the signal, maybe a 60 to 70us delay would come close to what you are seeing.

Including a couple charts I posted awhile back with US Nickel and Quarter targets. Three minor lines on chart doubles or halves the signal.

Does anyone have a working Hammer Head that could reply with the detection distance for a Nickel. Wondering if my guess of 40cm is way off.

[Carl-NC]

Since GPX coils easily works over TDI, do you think i should change HH1 range frequency to TDI range?!

Does the HH work well with any other coil?

Does anyone have a working Hammer Head that could reply with the detection distance for a Nickel. Wondering if my guess of 40cm is way off.

Probably more like 30cm.

[surfdetector]

Does anyone have a working Hammer Head that could reply with the detection distance for a Nickel. Wondering if my guess of 40cm is way off.

I get about 10" for a nickel on my machine

[waltr]

Does anyone have a working Hammer Head that could reply with the detection distance for a Nickel. Wondering if my guess of 40cm is way off.

Does the HH work well with any other coil?



Probably more like 30cm.

I get about 10" for a nickel on my machine

I get about 25-30cm.

[green]

Thanks for the replies. 25 to 30cm is less than I guessed but if I did my math correct it would still take about 100 times increase in S/N to increase distance from 4cm to 25 or 30cm. Reducing target delay for a Nickel about 40us could be one way, any others?