My Pulse Oscillation detector project.

[reptooyep]

Hi,
Firstly, thanks Teemo for his great work and sharing files.
I've just finished two boards. If someone is interrested into building SMD version (only 5.5cm X 2cm... and could be much less!! ), i share my work here.
I've added a BC848 transistor to get more power on the piezzo and i've taken off the diode which i don't know the use.
I power it with a single 3.7v battery with a dc to dc board (it can give more than 16v with 3.7v in and cost 1€ on ebay), see pictures.
Teemo 12F1840 SMD.zip

[6666]

http://digiwood.ee/8-electronic-proj...tector-circuit

http://digiwood.ee/shop

I did not have a problem and received an email from him as well
no connection to him just thought I liked this thread so would order one.

Thanks the web links early in the thread no longer work.

[David_1]

http://digiwood.ee/8-electronic-projects/2-metal-detector-circuit

http://digiwood.ee/shop

I did not have a problem and received an email from him as well
no connection to him just thought I liked this thread so would order one.

[6666]

just ordered a kit from Teemo mainly to show support for his open source attitude.
David

Where from his website no longer works ?

[David_1]

just ordered a kit from Teemo mainly to show support for his open source attitude.
David

[waltr]

O, what version software did you put into the PIC?
I run v1.8 so could make a difference.
Also, there are several modes, I run in Mode 1.

[reptooyep]

Oh, strange, i did not noticed any pitch difference with differents objects.
I'll test tomorow.
I have another coil to test with (the one from the video is the one from the right,
Tomorow, i'll test the other one

[waltr]

Here is the air test with a 20cm spider coil (350uH).
The pitch becomes lower when a coin comes close to the coil, it should be higher ???

non-ferrous object produces a Lower tone.
Ferrous a higher tone.

Try an iron/steel object then copper, brass, aluminum, lead objects.

[reptooyep]

Here is the air test with a 20cm spider coil (350uH).
The pitch becomes lower when a coin comes close to the coil, it should be higher ???

https://youtu.be/S2-BtTLF2VQ

[reptooyep]

First, thanks for your reply.
I read all thread quickly ... Maybe too much
My coil is 20cm circle.
I've put a BC 547 to drive the piezzo. It's a bit louder.
I've made several test with the parallel capacitor and get not so bad results
with 80nF instead of 47nF.
I wanted to use a 5v power bank but the one i have is not good.
I'll do the same as i always do : a 18650 battery with a dc to dc converter. I'll post results tomorow.
I have about 15cms for coin so, not so bad for a homemade kid toy.

[waltr]

reptooyep
Did you read through this entire thread?
The one observation is lack of depth compared to other MDs (PI or VLF).
What are the coil diameters?

It should not be too sensitive to coil but the high value cap, 1000uF, is a must and is best connected close to the MOSFET/Coil.

The piezo speaker is not loud at all. An audio amp is needed to drive a speaker.

[reptooyep]

Hi every one.
I'm making my son's first detectorand this circuit seems simple and tiny enough for a light rod detector.
I'm having troubles with coil. I've tested a 25 turns of 0.15mm coil and had a poor depth (about 5 cms for 1€).
Then, i've tested a spider coil with 0.5 mm copper wire and have a better depth but not so good comparing to other detector i made before (10cm for 1€).
I then made a simple coil with 20 turns of 0.5mm copper wire and have no functionning at all. I think my powr supply is quite light for this 0.5 ohm coil.
When adding a serial 1ohm resistor, it turns on but no detection.
Is there any adjustments on componment value to fit the coil ?
The sound is also VERY VERY low. It lacks a transistor to power a speaker. I'll do this tonight.

[waltr]

The diameter of the coil is about 125 mm, I used DVD cake box as a form. I have good results, but only in my garden, because in my country treasure hunting almost impossible legally. Even in my garden is illegal... I think this pinpointer very accurate in soil.

Ok. A shame its illegal. My grandparents came from Hungry in the early 1900's.

[fekemil]

I had old version of MPLAB IDE, today I have no problem with the new version. (After the stupid password-for-advaced-settings)

[fekemil]

The diameter of the coil is about 125 mm, I used DVD cake box as a form. I have good results, but only in my garden, because in my country treasure hunting almost impossible legally. Even in my garden is illegal... I think this pinpointer very accurate in soil.