Hi guys, I hope you can help me with this project. I have to find buried pipes (up to 3 meter deep) constantly and I need to build a locator. Did some research, found out that a transmitter inserted into the pipe can be detected at the surface, with a "locator" that has some kind of directonal antenna. There are expensive devices out there that work even in metal pipes, but I live in South America and have no way to get those gadgets. A small transmitter and receptor may sound not a big deal, BUT it has to work at 512 Hz (yeah, that low) frequency. The reason is that low frequency signals can reach to the surface much better than HF, even through metal pipe and concrete paving. That is where it gets complicated, since I cannot find much information about low frequency oscillators, amplifiers and antennae. Any info or linkl will help.