SBG- slow motion metal detector

[ivconic]

These days I am very busy with repairs to the roof of the building. So I spend more time outside and very little time with the PC.
I'll continue with the detector once I've finished that urgent business.
In the meantime, I came across old pictures from 2016 when I was coming to Vidin for the flea market, this picture is very dear to me:

[scs-bg]

It is very important how you wind the coils. They need to be of the same geometry. This way you don't get bad discrimination. It is good to wind the transmitter first. Then wind the receiver through it using a shuttle.

[scs-bg]

C 33+C 34 is about 47nf

[scs-bg]

A worse Q factor on the receiver results in a smaller ground effect. It's all a matter of compromise.

[ivconic]

The receiver coil is made of thin wire to make it lighter. This does not affect the inductance . It affects the Q-factor of the circuit. You can also make it with the same cross-section as the transmitter. The number of turns on the transmitter and receiver should be the same.

Its like you read my thoughts and intentions!
Because I had the same idea.
It resulted from the fact that the two micro coils (from the floppy disk) are identical and that the detector worked correctly with them.

[scs-bg]

The receiver coil is made of thin wire to make it lighter. This does not affect the inductance . It affects the Q-factor of the circuit. You can also make it with the same cross-section as the transmitter. The number of turns on the transmitter and receiver should be the same.

[pito]

From before, xx years ago, when I did a lot of coils for TGSL/IGSL...
I know from experience that the inductance of the coils changes significantly when the windings are brought close together and tightened with thin string, or wrapped with tape.
In this case, they are coated with superglue.
And it is very difficult to predict the final inductance.
It's one thing when the windings are just wound and the other is when they are tightened and arranged.
Of course, resonance can be fixed with capacitors.
But the difference of 0.6mH does not seem like a good minimum "jitter" to me and I will try to wind better and more precise coils.

I made a lot of coils (maybe 100), I'm not too concerned with the exact number of turns and inductance... I just placed a capacitor more or less in the transmitter coil, adjusted the transmitter frequency to it (only one capacitor in the transmitter coil), and then adjusted the receiver capacitor to achieve resonance.

[ivconic]

It's important to stay positive! I also had an operation with organ loss...now I'm in perfect condition!

Oh, don't get me started!
I'm so full of scars that women think they're tattoos!
Life lesson: always (mis)use all your flaws!

[ivconic]

I understand that we had the same desires. When a person is young, he has an interest in airplanes, space, ships. It stays for life. By the way, I am very satisfied with the Bulgarian doctors. After the operation, I feel good.

Glad to hear that!
Rest for a while and next year let's go Europe tour on bikes!
Let the youngsters do the rest.

[nejdet]

I understand that we had the same desires. When a person is young, he has an interest in airplanes, space, ships. It stays for life. By the way, I am very satisfied with the Bulgarian doctors. After the operation, I feel good.

It's important to stay positive! I also had an operation with organ loss...now I'm in perfect condition!

[scs-bg]

I understand that we had the same desires. When a person is young, he has an interest in airplanes, space, ships. It stays for life. By the way, I am very satisfied with the Bulgarian doctors. After the operation, I feel good.

[ivconic]

I have a new hobby. I'm tired of dealing with circuit boards and soldering irons.

From a young age, I dreamed of being a fighter-bomber pilot.
But I was rejected at school because I'm an "only child", I don't have any direct brothers or sisters.
And the law then strictly stipulated that only someone who had brothers and sisters could enter the school for pilots.
(in case of death, so that the parents are not left without children).
So I was denied that desire for life.
My two uncles were pilots, my father was a paratrooper... you can imagine how disillusioned and demotivated I was later in life!
But I replaced it with love for powerful motorcycles.
It's not the same feeling, but it's similar.
In the next couple of years, when I finish some real estate business, I plan to buy a 200 horsepower Suzuki Hayabusa and then cruise around Europe.
Seems crazy?
At 60 years old!?
No it's not!
50 years of life is the right age to get on a powerful motorcycle.
All the younger ones are just there to do stupid things and get killed.
Your airplane collection reminded me of my first love... which didn't come true.
MIG29 was my dream, the pinnacle that can be achieved.
I had the opportunity to sit in one for 5 minutes.
In the airplane museum... of course!

[ivconic]

And just when I started to slowly withdraw and move away from "physical jobs", this happened:

https://www.geotech1.com/forums/forum/technology/general-electronics/450218-weller#post450236

how can I resist now?

[ivconic]

Don't waste your time. You need to make a sensor with shielded coils and minimal received signal. Then remove the capacitor c33 10 nanofarads. In its place, put one or two capacitors that give the maximum received signal without moving the coils relative to each other. Try with a piece of ferrite, a small change of c33 may be necessary. A signal from any metal should be received when entering the sensor. If the signal is when leaving, swap the beginning and end of one of the coils.

Sasho I know most of this. Thanks anyway. I tried a shielding with thin Aluminum self adhesive tape and it breaks on many places, very bad quality. So next time I will use graphite spray instead.
It's been a long time since I made any diy coils, in tne meantime I didn't maintain my supplies of material.
Last 12-15 years all I made; I used various stock coils. Just because of the reason I hate making coils.
In the past, the aluminum self adhesive tape I remember; was of much better quality. Today they sell garbage.
This time I wanted to make coil just for the reason it is "OO" shape. It is interesting to me to experiment.
Once in the past I made one "OO" coil and it was good. But the aluminum self adhesive tape was of the highest quality, so it was easy.
During the TGSL/IGSL/SMW period I made 200-300 coils (lost count). Hopefully I learned something than!?

This is just a hobby. I do have dozen top metal detectors in my collection. I am not striving to make a detector as soon as possible and to use it for real, this is just a nice project and interesting to kill a time.
Same as you; I am also pretty much tired of dealing with such stuff. It was too much for a lifetime.
But... it's under my skin, too late to change and give up.
Hobby will remain as much as I live, for sure.

[scs-bg]

I have a new hobby. I'm tired of dealing with circuit boards and soldering irons.