Can't be much different than this project of Carl's. Maybe cost you $50 to build. Remember, if you can't use the L-rods these type of locators will not work for you no matter how much they cost or how many bells a whistles they have. Most people never learn to use the L-rods because they won't take the time and effort to learn some basic form of meditation to achieve a Zen-like state. Most people are quick to blame the locator or builder, but it's the person with the L-rods in their hand.
https://www.geotech1.com/cgi-bin/pag...mfd1/index.dat
And if i was going to build one I would buy a cheap DDS frequency generator and substitute it for the 8038 chip which is unstable and outdated, near obsolete.