Need this circuit printed circuit board

[eessoo]

not recommend changes I made. (lm308 with lf357) can be a sample. lf357 have lf356 otherwise use sensitivity drastically decreases.

u mean i should change the lm308 back to lf357??

[cristi71]

if you do not sound at all, the fault is with 555 and end audio oscillator. need to hear sound from the speaker even if part of the scheme with lm308 not work.,

[jap]

I tend more to the second part of answer .
j.

[eessoo]

there is somthing wrong with my NE555P or the BD140?
is there a diffidence between NE555 and NE555P?

[eessoo]

the speakers are working now
but it can't detect any metal
any idea what could be wrong?

[kt315]

the speakers are working now
but it can't detect any metal
any idea what could be wrong?

wrong? wrong... wrong!

no thanks i wanna build it my self

[eessoo]

????!!!!!!!!!!!!!!!!!!!!

[Watanabe]

Hello friends.

I mounted this circuit on breadboard, but could not make it work .

I have no response signal and once the T4 transistor (BD140) very heated.

Another thing that caught my attention is the link of PR2. Look at that, acting on PR2 to the end of your course, we connect +12 V direct discharge pin (pin 7) of IC4 which causes an internal short circuit in the 555 (IC4).

I know the wiring diagram is right because it is like the links in printed circuit board, however this seems very strange connection PR2... ...

Can anyone give me a help? Any tips?

I could also indicate some software (free ) for calculation of coil? Well in that case I'm using 27AWG wire (is what I have available here ...) and do not know how this affects the circuit ...

Thank you.
Greetings from Brazil!

[Watanabe]

Hello friends.

I mounted this circuit on breadboard, but could not make it work .

I have no response signal and once the T4 transistor (BD140) very heated.

Another thing that caught my attention is the link of PR2. Look at that, acting on PR2 to the end of your course, we connect +12 V direct discharge pin (pin 7) of IC4 which causes an internal short circuit in the 555 (IC4).

I know the wiring diagram is right because it is like the links in printed circuit board, however this seems very strange connection PR2... ...

Can anyone give me a help? Any tips?

I could also indicate some software (free ) for calculation of coil? Well in that case I'm using 27AWG wire (is what I have available here ...) and do not know how this affects the circuit ...

Thank you.
Greetings from Brazil!

[Watanabe]

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

[eessoo]

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

Nice work

[Freddy67]

Hello friends

I mounted the detector but I did the sound. The heater coil and the transistor T1 is hot. Where is the problem? R14 is 100 k in the diagram and 100 ohms in the list. What is the real value? Thank you for your answers and sorry for the google translation, I'm French.

[jap]

Hi Freddy67
-Test and Check the components in terms of value and correct the situation in place components in area ic4,t2,t1.
-Be sure to specification of coil.
-Be sure of value R8.
-R14=100k ,real value=91k.
best time
j.

[Freddy67]

Thank you Jap
I'll check these components. Ok for R 14 = 100 k.
R8> 180 ohms
The coil is made of wire of 16 m in a diameter of 25 cm, or 21 turns.
Greetings

[jap]

Hi Freddy67
Carefully read all the explanation in responsein reply#19.
best time
j.