According to reviews on the Internet, the spider coil can work with any pulsed metal detectors, but for proper processing of discrimination and selection, you need to make the coil as close as possible to the parameters of the author’s coil. The result should be a coil with a small parasitic capacitance, with the following parameters: L = 400 uH, R = 1.7 Ohm.
This search coil consists of 2 parts, 24 and 18 turns.
For winding the coil, you need to draw out the frame and make in it gash. The easiest way is to print and cut this template, attach it to the future frame and make notes for files.
In blue and red color designated the sizes of parts of the coil, green – zaplly.
This is how the coil will spin if you look at the coil from the end of the frame. Here brown is the frame with the gash, black is the round of the wire. The coils dangle “snake”.
At the end, it should look like this. Since the coils are wound with a “snake”, on the one side of the frame we will be able to see only half of the coils (12 sides.), The second half will be on the other side.
Coiling the first part of the coil, go to the second, containing 18 turns. We continue winding on the same principle, only on other gash. As a result, there should be 9 turns on each side of the frame.
After finishing winding we can measure the parameters of the coil using multimeter.