BARACUDA-Legend-1

[GeoMax]

From where have you bought your NE5534 IC chip?

[Deghbar613]

The response decay is way too slow. I suspect a fake opamp.

Yes it's fake i changed it with lf356 null offset works perfect but there is lot of noise so i will try find original ne5534
but in datasheet lf356 slow rate is 12v/us and ne5534 is 13v/us i don't know from where this noise

[Deghbar613]

From where have you bought your NE5534 IC chip?

From electronic shop here (algeria)

[GeoMax]

Oh, that's not good. I've heard this from other people too, that shops in Algeria sell fake ICs from China.

@Noise
I've taken a look at your PCB design. There's a ground loop on your circuit board. You should avoid ground loops. The ground loop might be picking up the noise. Just cut the loop somewhere. Also, the resistor in the negative terminal of the NE5534 is quite far from the actual IC chip. I would place it closer to the IC chip.

[kt315]

the noise is not good but not bad. Eric Foster told his case he did seek a noise in his electronic board. very long time waste.
it turned out ... to a lamp in one of rooms. 'economic eternal lamp' gave this noise.

[Deghbar613]

Oh, that's not good. I've heard this from other people too, that shops in Algeria sell fake ICs from China.

@Noise
I've taken a look at your PCB design. There's a ground loop on your circuit board. You should avoid ground loops. The ground loop might be picking up the noise. Just cut the loop somewhere. Also, the resistor in the negative terminal of the NE5534 is quite far from the actual IC chip. I would place it closer to the IC chip.

Thanks for advice GeoMax i will working on it
this forum is good for learing
Thx for all who help

[Deghbar613]

Hello everyone
Finally, I have built the Barracuda, deep is good 27cm on a coin ,but when I move the coil, it makes a noise.
What is the solution?

[kt315]

dirty test. delete metallic from around. for example, metallic nails in your table, corners etc. your coil must be hang in air on height 1+m. from roof 1+m.

[Deghbar613]

dirty test. delete metallic from around. for example, metallic nails in your table, corners etc. your coil must be hang in air on height 1+m. from roof 1+m.

I tested it outdoor the problem not there
indoor i am using this

[GeoMax]

Hello,
Perhaps the noise is caused by the cables in the wall, the fluorescent light, or the iron mat in the concrete floor, etc. – all possible sources of the problem.

[Deghbar613]

i found this picture in the forum


from where can i adjust delay position .
and why move delay to this postion ?
https://www.geotech1.com/forums/foru...ge10#post95849
thx all

[kt315]

you ask general principles how-PI-work. do you need to read ITMD? ITMD is a some book released by Carl Moreland and George O. Carl Moreland is an administrator/creator of this forum.
also, you can find all theoretics you so needed in an article HAMMERHEAD PULSE INDUCTION METAL DETECTOR by Carl Moreland.

[kt315]

[kt315]

[Deghbar613]

hello evryone
i need help
first i want gives some info
this is my PCB

this flyback

this ne5534_pin3

here is the problem
ne5534_pin6

when i remove R8(22K) i get this on ne5534_pin6

ne5534 not fake
please any help
thx