I played with the coil today. It's really sensitive. I was able to find a lead bb at 3 inches. It's also deep. I'm able to find bronze targets 1/2cmx1cmx2mm at 8 inches. It's also a very quiet coil. If I keep the coil at a consistent level off the ground (which can be difficult since ground isn't naturally leveled), I notice a very stable threshold every time, which surprised me. Ground balancing helped out a lot with stabilizing this coil.
The only problem I'm having is the aforementioned issue with lowering the coil. As it approaches the ground, the machine sounds like it hits a large target every time. it's really annoying, and I know I could improve the coil by shielding it. I just don't want to ruin the coil by using the wrong shielding material. I really need your advice on this issue guys. My SD 2100 v2 should not be that different from the SD 2000 in terms of components.
Could it be due to the coil having a larger number of windings and therefore more capacitance than the machine could handle? I measured capacitance at 18.98 uF.
I also read some where that the coil needs to be grounded. What does that mean? How would you go about grounding a coil housing? where would you ground the wire? right now, the two sole wires from the microphone cable I'm using are connected to the RX and TX terminals. I striped the copper ground wire mesh that was inside the cable to stabilize the coil.
By the way, some more coil specifications in case you don't have a LCR meter, and would like to construct the coil:
Windings: 39 turns
Outer Diameter: 7 and 1/2 inch (exact)
Wire type: Litz 330/46 with nylon shielding
Inductance: 301 uH
Resistance: .898 OHM
Capacitance: 18.98 uF (measured at connector)
I was able to attain a better inner circle by winding the coil to 7 1/2 inches (The eight .10 US dimes were placed at 2 inches from the center), and then removing 5 turns from the inner circle. It allowed me to remain very close to the required 300 uH inductance. However, resistance is close to .9 OHM and is not effecting performance as I expected (Could the coil be even more sensitive if its resistance was at .5 OHM?). The coil remains quiet sensitive.
Last issue that I'm having is the coil's sensitivity to hot rocks. I dug faint signals thinking they were small lead shards. Once I dug faint signals, I noticed they were hot rocks. It frustrated me since I particularly got rid of my old vlf metal detector because I got tired of digging the hot rocks. Is the spiral coil design not suitable for hot rocks?!?!? I was told PI was better at avoiding them.
The only problem I'm having is the aforementioned issue with lowering the coil. As it approaches the ground, the machine sounds like it hits a large target every time. it's really annoying, and I know I could improve the coil by shielding it. I just don't want to ruin the coil by using the wrong shielding material. I really need your advice on this issue guys. My SD 2100 v2 should not be that different from the SD 2000 in terms of components.
Could it be due to the coil having a larger number of windings and therefore more capacitance than the machine could handle? I measured capacitance at 18.98 uF.
I also read some where that the coil needs to be grounded. What does that mean? How would you go about grounding a coil housing? where would you ground the wire? right now, the two sole wires from the microphone cable I'm using are connected to the RX and TX terminals. I striped the copper ground wire mesh that was inside the cable to stabilize the coil.
By the way, some more coil specifications in case you don't have a LCR meter, and would like to construct the coil:
Windings: 39 turns
Outer Diameter: 7 and 1/2 inch (exact)
Wire type: Litz 330/46 with nylon shielding
Inductance: 301 uH
Resistance: .898 OHM
Capacitance: 18.98 uF (measured at connector)
I was able to attain a better inner circle by winding the coil to 7 1/2 inches (The eight .10 US dimes were placed at 2 inches from the center), and then removing 5 turns from the inner circle. It allowed me to remain very close to the required 300 uH inductance. However, resistance is close to .9 OHM and is not effecting performance as I expected (Could the coil be even more sensitive if its resistance was at .5 OHM?). The coil remains quiet sensitive.
Last issue that I'm having is the coil's sensitivity to hot rocks. I dug faint signals thinking they were small lead shards. Once I dug faint signals, I noticed they were hot rocks. It frustrated me since I particularly got rid of my old vlf metal detector because I got tired of digging the hot rocks. Is the spiral coil design not suitable for hot rocks?!?!? I was told PI was better at avoiding them.
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