How To Make Your Metal Detector Operation Wireless - Tutorial, page 6
Make Optimal Container for Digital Transmitter
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Since the transmitter must be electronically connected to a metal detector, one hole must be made in the transmitter's container to run a connecting cable through it. To achieve full protection for the transmitter against water and dust, I had to do the following: 1) make a sizeable depression upward in a lower corner of the container (when it is set upright against the armrest) to prevent the water from reaching the hole, and 2) make a hole inside the dimple, which would be tight enough to prevent a 3.5mm plug of the connecting cable from moving back and forth inside the hole once the plug is implanted into it.
To make a sizeable dimple in the container's corner, I filled a metal Saute pan half way with water and brought it to a boiling point on my cooking stove. I also prepared a second pan with ice cold water.
My idea was to press the container's corner against a hot bottom of the Saute pan being heated to soften the corner while the boiling water would prevent the plastic from melting.
Soften Plastic Container's Corner Pressed Against Heated Metal in Boiling Water
As soon as the plastic was soft enough, I took the container out of boiling water and pressed a dull end of a wooden cooking spatula (be careful not to break it) against the container's corner.
Make A Depression In Container's Corner
As soon as a little depression was made, I immediately submerged the plastic container into the ice-cold water to harden the plastic so that it would not return into its initial shape.
Cool Plastic Container Down in Ice Cold Water
Since my method was not highly efficient (but better than nothing), I had to repeat the above-described procedure a few times to get, little by little, desirable results - the depression was deep enough to conceal at least a half of the sticking-out connector. Another good use of the corner depression was to protect the plug from accidental knocking off as, without a dimple, it would be sticking an inch out of the container and fully exposed to external damaging forces.
Sizeable Dimple in Container's Corner