Need this circuit printed circuit board

[Freddy67]

Hello to all

The results of my latest research. I have 110 Hz on pin 3 of IC4. If I touch points 1 and 2, 8 and 9 from Ic2 with my meter, sound comes out of the speaker as if an object is detected.
The coil is disconnected and the transistor T1 and R 6 are lukewarm. As soon as I plug the coil T1, R6 and coil heat. Other components are ok.
Some thoughts on the failure?
greetings

[jap]

Hi Freddy67

R8> 180 ohms
The coil is made of wire of 16 m in a diameter of 25 cm, or 21 turns.

R8>>180~1.1K ?
What wire diameter?
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The coil is disconnected and the transistor T1 and R 6 are lukewarm. As soon as I plug the coil T1, R6 and coil heat.
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-Suspicion a percentage of a large mistake in the coil.
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The results of my latest research. I have 110 Hz on pin 3 of IC4. If I touch points 1 and 2, 8 and 9 from Ic2 with my meter, sound comes out of the speaker as if an object is detected.
---------------------------------
-This Normal.
best time
j.

[Freddy67]

Hi Jap

Thank you for the answers. The diameter is 0.5 and the length of 16 m> 21 turns. The transistor Q1 and R6 even heat the coil disconnected. I think a reversal of transistor T1 or mass problem. 'll Check today.
Greetings

[Freddy67]

I found the HUGE failure. In fact, printed circuit error. R5, instead of being connected between base and emitter and + 12 V, was connected between the base and ground. Transistor T2 permanently saturated. The location is good but the circuit layout to be reviewed. As I put the components where there were holes .....
Thank you for your explanations helped me to deepen my research.

Ps: any npn transistor T1 works. I detect a € 2 coin to roughly 20 cm. I tried a coil roughly 80 turns. It works but the yield is slightly reduced. I will continue to wound others to compare the results.

[kt315]

I just design now.
I added a resistor.
Let's see how it looks.

try to find and install FinePrint and you will get good pics from your CAD.

[jap]

Hi Freddy67
I understand where the mistake as u explained .This excellent work.
This is one of the excellent projects - tried to work coil appropriate for with the pcb and you will get excellent results . -- Try Coil, 20cm diameter of 25 windings of insulated copper wire 0.6mm= (~22AWG).Do not waste time about 80 tu.
best time
j.

[Watanabe]

Thank you eessoo
Thank you kt315

I finish my Polish-PI, and he works!!!!!!
But sensibility is small ...
I don't have 24AWG wire, so i used 26 AWG... i need verification it (turns, diameter...)

As soon as possible i send the details.

Best regards for all.

[eessoo]

congratulations!!
what did you do? i still can't get mine to work
and the coil should be approximately 16 m wire with a diameter of 0.5 ... 0.6 mm.
coiled in a circle with a diameter of 30 .. 40 cm.

[jap]

Hi Watanabe,eessoo
>Watanabe good completed work ,Polish-PI is one of the excellent projects can get good results.
use Standard Coil, 20cm ,25tu,.6mm= (~22AWG).
if u have .4mm=26 AWG Coil 20cm,24tu,.4mm.
Coil 40cm,16tu,.4mm.
>eessoo
if u have .5mm=24 AWG Coil 20cm,25tu,.5mm.
Coil 40cm,16tu,.5mm.
best time
j.

[Watanabe]

Hello folks!!!

Well, i give details:
IC1 (LF357): I used TL071.
T1 (BD911): I used 'TIP41.
coil: 24cm, 24 turns. 26AWG
Sensibility: 2,5cm diameter coin ( 1 "real" from Brazil ) = 15cm distance (not so good... )


But, at this time D1 (zener) burn ... (OH **** )...
Next monday I repair...

Greetings from Brazil!!!

[jap]

Hi Watanabe
T1 (BD911,TIP41)not equal of point amps , and this is important.
Read reply#35,36,37 , about D1.
best time
j.

[Watanabe]

Hello Jap.
You're right:
BD911 = 15A
TIP41 = 6A.
But the operating current is much smaller than 6A, then no problem.

Yesterday I tried to change the TL01 for TL081 and it worked well, but no improvement in sensitivity.

After, the circuit has stopped working ... Tomorrow I will check it at work (I not have an oscilloscope in my house...).

I find it strange connection of PR2 in IC4. Acting PR2 to the end of your course, connect +12 V on pin 7 of IC4. Has anyone seen this??

Thanks Jap.
Best regards.

[jap]

Hi Watanabe
- about T1 (BD911,TIP41) see datasheet Section relationship Ic,V,Fbw.(BD911 is a safe).
-lf357=lf356=lm318 best sensitivity.
-about PR2 in IC4 its ...OK.
best time
j.

[Watanabe]

My first metal detector:

http://www.youtube.com/watch?v=6ftcYbugpUM&feature=plcp

I ask for a suggestion for my second metal detector:

Surf PI or Barracuda?? Or other?? What??

Thanks to everyone for the tips.

Greetings from Brazil!!

[Freddy67]

Hi Watanabe

Very good job. Why the pcb upside down?
I am currently completing mine and the next will Tarsos with discrimination.

Regards