Simplest PI detector possible?

[brucester]

R2 can be played with using a 555 timer calculator. Google one.

R7 is tricky without a scope to set. Just trial and error a bunch of values from 100 to 400 ohms. But the default one in the schematic worked for me.

My coil is 10cm diameter, 400uH, 42 turns of 0.5mm copper enamel wire.

[Watanabe]

Russian Pirate PI Metal Detector (2nd Attempt).

Some modifications and a slight improvement.
Nice work's, but still not good enough.
Suggestions for enlarge deep range ?
Thank you.

[mikebg]

More deep with IB search head

[QUOTE=Watanabe;167004]Some modifications and a slight improvement.
Nice work's, but still not good enough.
Suggestions for enlarge deep range ?
/QUOTE]

For more deep range, use induction balanced search head (separate RX coil). Three IB configurations are suitable: DD, concentric and orthogonal.

[Watanabe]

For more deep range, use induction balanced search head (separate RX coil). Three IB configurations are suitable: DD, concentric and orthogonal.

Thanks Mikebg, but it will not change much the essence of this idea is to create an PI circuit as simple as possible?

Well, I have not the slightest idea how to do what you said ... Could you make an electronic scheme?

Thank you.

[mikebg]

VERY SIMPLE

Thanks Mikebg, but it will not change much the essence of this idea is to create an PI circuit as simple as possible?

Well, I have not the slightest idea how to do what you said ... Could you make an electronic scheme?

Thank you.

Simply disconnect R8 from TX coil and connect it to RX coil. No need to change PCB.

[Qiaozhi]

Simply disconnect R8 from TX coil and connect it to RX coil. No need to change PCB.

You will (more than likely) also need a damping resistor across the RX coil.

[bernte_one]

hello

if you make a separated coil (rx and tx)
take a bigger wire diameter for tx and an inductance which is small
wire 0,5mm+ and L max 300microH (22turns)
and for rx
0,3mm and around 1mH-1,3mH (50 turns)
balance to a null voltage under 10mV or better

specs fit to the coil shells 27cm dd till 32cm dd offered also here in forum

good luck

[mikebg]

You will (more than likely) also need a damping resistor across the RX coil.

No need of additional damping resistor because there is negative feedback. Resistors R8 and R11 form a nonlinear damping network. Linear analysis shows that input impedance at inverting input of opamp is in theory zero.

[Carl-NC]

Linear analysis shows that input impedance at inverting input of opamp is in theory zero.

At steady-state, yes, but not during transients. Ringing will depend on the amount of coupling with the TX coil.

[Watanabe]

Thanks everyone.
I go try something.

[Watanabe]

I made several attempts, with coils of various types, and not get better than this result:

http://www.youtube.com/watch?v=SqNeJegCjHU






I can not say, but I believe that better results are possible only with great changes in this circuit.


Thank you all.

[tittus]

I did the layout # 14 6666. Works perfectly, 5 euro cent coin to 20cm, 90mm round iron 50 cm, I used 13007

[6666]

Thats good news tittus.

[WM6]

I did the layout # 14 6666. Works perfectly, 5 euro cent coin to 20cm, 90mm round iron 50 cm, I used 13007

Conratulations. Can you post some photos of your work?

[Watanabe]

I did the layout # 14 6666. Works perfectly, 5 euro cent coin to 20cm, 90mm round iron 50 cm, I used 13007

Congratulations tittus.
Please, can you show us your job??


Thanks.