Ximimark 2Pcs Metal Detector Kit Electronic Soldering Practice Kit Non-Contact Sensor Board Module Electronic Part Metal Detector DIY DC 3V-5V 60mm

i built an automated robot with mapping abilities and programmed it to use metal detectors and search an area for items made of metal. they have proven very reliable

0/8 purchased kits had the one required S9018 NPN transistor + two S9012 PNP transistors. Most kits had two transistors only usually NPNs. In addition 8/8 kits included one 4.7K ohm resistor (not required), but were all missing the one (required) 470 Ohm resistor. No instructions, no part orientation warnings for polarized capacitor, polarized LED, and polarized switch none of which (of course) are keyed. You must carefully place parts by (1) silkscreen hints (like silkscreen notch on switch), ground plane that connects to polarized capacitor (-), and LED anode must be identified from LED datasheet (not included). Does not include case, battery holder, mounting hardware or handles required for actual use. Purchased as gifts, but probably not worth the money when all issues are considered. CAVEAT EMPTOR indeed! No schematic diagram or explanation of circuit theory (a lost opportunity to inspire our overly video game addicted society; a shame really as this kind of kit is exactly what got me interested in Electrical Engineering many years ago. I do not yet know if it actually works, with 8 kits and not enough parts of the right kind to finish even one. I saw no way to simply get the parts I am missing from the vendor; sending the kits back is not worth the postage. AVOID.

Fun project to kill an hour or two. Yes, the sensitivity is <60mm! More like 10mm. Wish the assembly instructions were included with the parts. The 470 ohm resistor was delivered as a 4.7k ohm. Don't know why an extra 10uF capacitor was included. Works with a 2032 button battery.

Okay, so I actually bought these because I needed something to check boards for nails, staples or pins before I tried to saw them. I'm still working on that.The devices are easy to solder together correctly if you are careful. The silk-screened component values on one side of the board is the only guide you have, there are no written instructions. There are a couple of YouTube videos where folks have posted their assembly experience. Be careful though, I watched at least one video that reversed the polarity of the main power switch, they complained that the switch turned on and off in the opposite way that they expected. Apparently they didn't see the small notch in the picture which illustrated the correct orientation.But, even if you do put it together correctly, variations in assembly and the values of the various resistors may leave you with a device that is not sensitive enough to be useful for your application. A slightly better design would have remedied this, I think. It's like the sensitivity adjustment doesn't quite turn far enough (LOL). There is some variation between the various editions of this kit available on Amazon. They are distinguishable by the quality of the printing on the board. Some, like this one, are missing the part number for one of the transistors. Once you place the two that are labeled, the one that's left...well, you get the picture. (See Q1 in the attached photo).Of course, after you put it together, you'll be faced with what kind of case to use for it. I'm still working on that too. By the way, the power supply needs to be 3 to 5 v. I've found that it works about as well with a 3v supply as a 5v one. So, a couple of AA batteries in a holder is all you need.

Very useful metal detector to start making a big one. Good and affordable price!