Metal detector for medium-large objects

[haylaz0036]

Hi haylaz0036,

If you want to make a single-layer PCB, be aware that it will either be impractical or end up the size of a dining table. Why do you want to make a single-layer board? I used to etch and assemble almost all my PCB projects in two layers at the kitchen table. By the way, the PCB for the GS5 Lite is already available.

Dear Engineer Geomax, I just couldn't manage the double-sided printing—the holes wouldn't align—so I'm going to make a single-sided PCB. I watched the video; the range is excellent, and the sound is fantastic.
Is it possible to get a list of materials? Where can I find it?

[haylaz0036]

Is it possible to get a list of materials? Where can I find it?

[dbanner]

Is it possible to get a list of materials? Where can I find it?

Sprint Layout, open components window.

[dbanner]

missed some holes.

[haylaz0036]

[haylaz0036]

Dear Banner, what do these trimpots do? Also, I don't have a VU meter, so can I short-circuit the input terminals? And what are those LEDs for? I would appreciate it if you could mark the trimpots on the PCB layout.

[dbanner]

VR1 - Input Offset Voltage Nulling (or Balancing)
VR2 - Frequency adjust (2.6kHz - 3kHz). This is the pulse repetition frequency (PRF)
VR3 - Sample Offset Calibration
VR4 - Tone
VR5 - Adjustable battery low-voltage monitor / warning indicator circuit.


Note: VR1 is a manual, one-time setup calibration trimmer. By physically rotating VR1, you micro-adjust the internal emitter/collector current balance inside the op-amp's differential transistor pair. This allows you to apply a precise counter-voltage internally until the output of U1 sits perfectly at 0V DC when no metal target is present at the coil.

Don't you have a schematic? Of course you do. So don't ask. You have everything you need. Good luck.

[haylaz0036]

Dear Banner, thank you very much for your interest. Finally, how should the coil be made—is it a dual coil or a single coil?

[dbanner]

Single mono-coil. PVC insulated 24 gauge AWG wire.

Anything between 300uH to 400uH is optimal.

[dbanner]

This type of wire makes a faster coil (less coil capacitance, higher SRF)

[pito]

Metal detector for medium-large objects = show pictures of the objecst and tde distance of detections

[GeoMax]

This type of wire makes a faster coil (less coil capacitance, higher SRF)

Hi Dbanner,

Which type of wire do you mean? Do you have a picture or specs or description?

[dbanner]

Teflon(PTFE) wire is very good for low interwinding capacitance (jumble wound mono-coil), PVC insulated is better than magnet wire.

Here is a search coil I am building at the moment. It is a dual field coil for my Minipulse detector.

[dbanner]

I use this circuit to quickly measure the coil parameters:https://www.robkalmeijer.nl/techniek...e48/index.html

I find that it is most accurate if care is taken in its construction It allows me to find the actual coil capacitance and inductance of my DIY coils. And SRF.


I made an app for my desktop based on the equations. So it is super easy for quick measurements. A frequency meter is all that is required.

[Detectorist#1]

Hi dbanner,
Thank you for this very interesting information! Just one problem - 2N5245 is very old and now it is very hard to be find. It will be useful for all us if you have possibility to test this design with J113 transistor. This type is still in production.