by "The Prof"
This project comes from the October, 1988 issue of Practical Electronics. This is a phase-type VLF detector which utilizes a very simple coil configuration. In fact, it is an example of a TR detector that is not induction balance! The author claims that it does well with the "ground effect" but he is talking about ground capacitance, not mineralization, and the design does a poor job (if any) discriminating between precious metals and junk. However, it is good reading for learning about phase detectors and might make a good starting point for designing a decent VLF discriminator.

Practical Electronics is now known as Everyday Practical Electronics , a popular electronics magazine that is owned by UK publisher Wimbourne Publishing, Ltd. I would like to thank Wimbourne Publishing for giving me permission to post this online version.