The Kid FM2 circuit is a bit complicated compared to the simpler "Kid FM”, Added new parts, added light indication of metals, the sound in the speaker is amplified (headphones are not needed), and the device itself has become more stable in operation. But all these improvements will not hinder to assemble it to people far from electronics.
The device is powered by a simple crown 9c, the detection depth is basically no more than the diameter of the search coil. Perfect homemade metal detector for the beach or to the lookout.
For assembly we need:
1) Textolite
2) Drill
3) Varnished copper wire 0.3mm
4) Soldering iron
Here is a diagram of the improved Kid FM2
I specifically made the board for DIP components, it’s easier to mount
I must say right away that the capacitors C2-22nF and C6-100nF should be film
We place all the details on our board according to the scheme
There are circuit boards on the Internet. But they are all in SMD, I did not find in DIP, so I did mine. I will post the file with the board below, but the details and jumpers are not signed on it, so it will take you to collect from the photo or make your own board or SMD.
Well, everything is soldered into place
Voltage stabilizer AMS1117 -3.3v.
I advise you to take the LEDs in different colors, I took red for ferrous metal and blue for non-ferrous.
Proceed to winding the coil. The diagram says about a coil with a diameter of 15cm. But I decided to do less, because the smaller the coil, the finer the find she sees, if the coil is large, then the detection depth is slightly larger. But she sees little goals. Since the detection depth is not very large in this metal detector, I decided to make a 10-11 cm coil for myself. To do this, you need to wind a wire on a 10 cm mandrel (I don’t have 0.3, I wound 0.4) 130 turns.
Coil as in first baby wrap with tape and screen.
Here is a photo of the entire device assembly
Next, you need to flash the microcontroller and you're done.
When you turn on the device should make a sound (peak-fute), if the Fute is, then the device turned on and started working.If at all, I didn’t pick it, then the error in the board or not working quartz.
If you pick it up, but there is no treasured Fute, then either the coil is not wound correctly or the wrong capacitor C2 is 22nF. It didn’t start for me for a very long time, everything was picking and picking, but there was no treasured Fute. It turned out that instead of a 22nF film capacitor, I put a simple ceramic one and did not tighten the coil tightly and did not shield it.
Basically, the device is not very difficult to assemble, the main thing is to flash the microcontroller, who does not have a programmer, please contact, I will help with the firmware or in comments.
Below I posted a video of the metal detector, as well as firmware and board files in DIP.
VIDEO WORKS
FIRMWARE
PAY