help with surf pi, trying to make it work!!

[ApBerg]

some help please? this thing is totally unstable

Power ok now, the currents are normal .. , have you updated the NE5534 ?

Can you find now a zero DC at NE5534/6 when adjusting the offset pot ?
If so then turn the delay potentiometer and see if you can detect gold..

[pavlos_x]

Power ok now, the currents are normal .. , have you updated the NE5534 ?

Can you find now a zero DC at NE5534/6 when adjusting the offset pot ?
If so then turn the delay potentiometer and see if you can detect gold..

NE5534/6 is adjusted to zero and with offset to midle(changed the pot with a diferrent one)

http://i.tfcdn.com/img2/J98tLk4AY5r8...OAA**/fyVMtP8A

''have you updated the NE5534?'' we had problem with 2n3906 and i putted a bc307a, but i had it otherway around now i fixed it's fine. i detect iron at 10cm and gold at 2cm i changed 4 coils and still the same results.

[pavlos_x]

coils that i tried are

wire(with pvc shield) 0.5mm 17turns 20cm diameter ----> big iron at 7cm
wire(with pvc shield) 0.5mm 22turns 20cm diameter ----> big iron at 10cm
wire(with pvc shield) 0.5mm 17turns 27cm diameter ----> big iron at 10cm
wire(naked copper) 1mm 17turns 20cm diameter ----> nothing just buzzing

[pavlos_x]

something is keep buzzing all the time but it detects, my distance of detect is too small, is something wrong apberg??
i even made another coil

wire(with pvc shield) 0.5mm 24turns 20cm diameter ----> big iron at 10cm

[silverdog]

are you adjusting offset for each coil ?

buzzing sounds like bad coil

adjusting delay may take many turns, the pots I supply are 25 turn pots
It sounds like you are almost there, maybe just a resistor in wrong place?
can you post some more pictures, close up of each part of the board so we can see the resistors colors ?

[porkluvr]

NE5534/6 is adjusted to zero and with offset to midle(changed the pot with a diferrent one)

http://i.tfcdn.com/img2/J98tLk4AY5r8...OAA**/fyVMtP8A

''have you updated the NE5534?'' we had problem with 2n3906 and i putted a bc307a, but i had it otherway around now i fixed it's fine. i detect iron at 10cm and gold at 2cm i changed 4 coils and still the same results.

Any time you have power supply reversal it can cause incidental damage to components. Your having +4V where you should have had -4.5V was such a reversal.

You should replace the '4066 then think about replacing the opamps if you still have problem. Make sure you do not use 74HC4066.

edit: Thanks for the schematic and link, ApBerg.

[pavlos_x]

YES am adjusting it to zero each time, i changed delay pot to this
http://i.tfcdn.com/img2/J98tLk4AY5r8...OAA**/fyVMtP8A
because i broke it :P

its too dark to take a good foto and with flash you cannot really see well

i just test all resistors with multimeter

all resistors are ok from your side part list except these:
R11 is 12.8k instead of 22k
R22 is 88k instead of 100k
R20 is 5k instead of 22k

[pavlos_x]

[UFO]

Is R25 soldered?

[Qiaozhi]

I suggest you replace C1 and R2, which have been damaged by the soldering iron.
.
.

[porkluvr]

Nooo, man. Those dings just add character to the final product!

[pavlos_x]

being sarcastic doesn't make you smarter! i was planing to change them, i had no choice, i had to make the soldering on top of pcb where the problem was and then check it with components on to see if its ok, R25 is ok

[porkluvr]

being sarcastic doesn't make you smarter! i was planing to change them, i had no choice, i had to make the soldering on top of pcb where the problem was and then check it with components on to see if its ok, R25 is ok

I guess I can never be as smart as you are, or have such a good sense of humor. Oh, well.

[pavlos_x]

chill out my friend just messing with you