Metal detector with meter discriminating

[Qiaozhi]

I see that in the circuit that you give the + and - are reverced!!
Is this because I am begginer,and cant read between the lines?Or there is mistake?
Thanks

p.s.can I use 50-0-50 ma meter for this scematic?

Hi Geto,

Some people will draw an opamp with the - (inverting) terminal at the top and the + (noniverting) terminal at the bottom. Others like it the other way around. You just need to be careful when you build the design, and note the correct connections. This can often lead to mistakes, especially when the two are mixed together in the same schematic, which is not good practice.
In other words, just make certain that you connect the inverting terminal to pin 2 and the noninverting to pin3. Essentially it makes no difference which method you use.
It looks like this detector requires a 50-0-50 uA meter, but Sasho should be able to confirm this.

[Geto]

to Sasho-bg

I see that in the circuit that you give the + and - are reverced!!
Is this because I am begginer,and cant read between the lines?Or there is mistake?
Thanks

p.s.can I use 50-0-50 ma meter for this scematic?

[Geto]

NOT To Qiaozhi SASHO!

I post this question!NOT Qiaozhi
I am now trying to make PCB for this schematic of yours and found that:

To Qiaozhi
No.Schematik is correct.

[Qiaozhi]

Hello,
Sasho.
I am trying to make this PCB,but its look like pin configuration on IC CA3140 is reverced!!+and-????
Am I right?
Please explain!
Thanks

Why do you think the inverting and noninverting inputs are reversed?
Looks ok to me.

Hello,

Hello,
Sasho.
I am trying to make this PCB,but its look like pin configuration on IC CA3140 is reverced!!+and-????
Am I right?
Please explain!
Thanks

to Sasho-bg

Hello,
Thanks Sasho!
I will try to build this hope it will work as expected!
This will be great.
Thanks

ps.What is this 50-250 scale?
I easy can find 50-0-50 mA!Can I use this?
In your chematic you have marked that scale is +0- 0.05mA????

sfd106-sfd112=germanium diod-no problem.
meter 50-250 mikroamper.Adj. with R29.

No. Work well with VCO sound oscillator.

to SAsho

Hello,
I have found sfd112!
How do you think can I use this?
Will this affect the circuit?
Thanks.

to Sasho-bg

have you thinked for LCD?
I see that there are aveilable it will,be much more easy then searching 0,05-0-0,05 ma scale!
What do you think?
Thanks

to Sasho-bg

Hello,
Thanks!
I will try this!
Can this baby handle whit so called hotrocks,or you havent chance to check this?
If you have invent this its realy a thing that you can feel proud off!

D for coil -0.27mm or 0.31mm
sfd107,8,9=germanium diode
Coil positioning to minimal level signal without c5.

to SAsho

Hi,
Can I use some other diode insted of sfd107?
I cant find this one!
Please avice me.

sasho-bg?

Hello,
Very intersting!
Well done,nice job!
Did you invent this or its your tuning on somthing else?
What is d for coil?
Thanks