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

This kit is poor. There are no instructions and the part values in mine don't match what is labeled on the silkscreen. It doesn't detect metal worth a hoot. I have to touch an object to the coil to get it to trigger but then it triggers on non-metal objects as well. They also made a poor choice for the transistor footprints, making it difficult to hand solder.

Great circuit even though VR1 pot is labeled as 1K ohm the pot is actually 100 ohms. I ran an external wire from the buzzer input line with a 10K pull down resistor to my external circuitry. It works very well.

Assembly took about 1 hour , with 1 resistor missing from kit, that I supplied myself. As there are no instructions care must be taken over the 2 different types of transisitors and the polarized components such as transistors, LED & electrolytics. The metal detector worked immediately and well, so for the price this is a good product but not something most kids could assemble correctly without assistance.

The PCB itself has enough silk screening to know what goes where, but I'm not sure this kit actually includes the right components or components that aren't trash anyway. One of the silk screens looks like it might say 200k but there's no 200k resistor. It might be a cut-off R, which is closer, but it comes with a 220 ohm resistor, not a 200. There are two spots for '104' ceramic capacitors, which should be 100 nanofarad (100000 pF). There's a 104 marked cap, but it measured 74 nF and a cap marked 10 that was 65 nF. I assume the 4 just didn't get stamped or got rubbed off. But being 35% off is way out of any tolerance range. I'm also not sure what would be a viable power supply for this to even mess with it around the house. I guess I need to find a 5v wall wart and cut the plug off the end? Or use a bench supply and only use it near where I assembled the thing? Either way, it was ok for a few components to practice the soldering itself, but very poor for having a toy to play with at the end. Just landfill junk once it's complete.

My kids had a lot of fun assembling these metal detectors, but they don't really work. At best, there is a constant squeal and it changes pitch when it detects metal. YouTube videos confirm how they work. Worth the $5 but clearly not a usable metal detector.

Both kits missing the 9012 transistor leaving the boards useless. No included instructions. Resistor values don't match instructions on listing.

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

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.