TGSL coil + audio problem

[Xavier]

Hi Guys

Well I have been reading all of the posts regarding the 2 tone mod. I also read most of the posts on the TGSL and having done that I thought that I could build it without having any major issues, well I was almost right. I have had a major issue regarding the coil, once the coils was wound I would use dental-floss to tie it tight then check the inductance, as I was always a bit over I would remove a turn or two and that would bring me to almost spot on induction, but once the super glue was applied the inductance went up by 1.2mH then would settle down 600 - 700 uH above the required inductance. The second problem that I'm having is the audio, the ferrous sounds normal but with non-ferrous objects I get both the tones at once (low and high tone) unless the object is very close to the coil. Any advice regarding this would be great.

All the best
Xavier

[Xavier]

I was just wondering how long dose it take to get a reply? or will I ever even get one?

[dfbowers]

Xavier,
I can at least offer a solution to your coil problem. Build a 2 sided coil former and wind your wire on the form "sticky". Use epoxy or varnish. You would have to use a liberal application of mold release or wax to get it off the form but inductance should never change. If you are ever going to make more than one coil, this could save you a multitude of headaches.
Don

[Qiaozhi]

I was just wondering how long dose it take to get a reply? or will I ever even get one?

Be patient. Sometimes it can take awhile to get an answer, especially if it's to a very specific question like the one you're asking.
You will have to wait for someone who has successfully done the 2-tone mod.

[Xavier]

Hi Don

Thanks for the reply. I did make the same coil former but I did not glue the coil whilst in the former. Can you tell me what release agent should I use?

Regards Xavier

[mikebg]

Hi Don

Thanks for the reply. I did make the same coil former but I did not glue the coil whilst in the former. Can you tell me what release agent should I use?

Regards Xavier

Xavier, please explay me with other words what means "release agent". I have problem with English language.
I designed a former in which can glue the wire and easy remove the wnding. Here is its drawing.

[Jabberwock]

Hi there,

release agent is something that will avoid the wires and glue to glue to the wood.
It can be as simple as vegetal oil or liquid paraffin.

[Xavier]

Hi Mikebg

The first coil former that I build had nails instead of the wood dowel pins and I found that there was a difference in inductance once the coil was removed from the former yet on your coil former design you have used two steel plates do you not have a change in inductance? also I don't quite understand the purpose of these plates, could you please post a photo of your former. On my former I did the mistake of rounding of the sides too much so I will need to make a new one. I was looking at the data sheet for the J107 and the 2n4391 as a substitute and found that I should have got the 2n4393 instead ( a stupid mistake on my part).

All the best
Xavier

[mikebg]

Xaviar, Surely there is a change in inductance, but it is negligible. In fact, inductance is not measured at series production. The number of turns is determined only making the first piece.
The advantage is that the coil is made quickly.
Pipette one drop instant glue in the gap between two metal lameles and coil is immediately ready for removal.

[Xavier]

OK now I understand your concept, thanks for sharing that with me just one more question why do you have the oval holes? why not just round holes if the plate just rotates?

All the best
Xavier

[mikebg]

OK now I understand your concept, thanks for sharing that with me just one more question why do you have the oval holes? why not just round holes if the plate just rotates?

My idea was once shot a drop glue in each distance between the plates, they will shift slight in direction to the central axis to facilitate paste the entire surrounding area of coil. Suggest that greater strength of coil is required before it off from the mold. Later it turned out that it was unnecessary because instant glue makes sufficient strength of coil.

[Xavier]

My problem was that once the coil was glued the inductance went sky high then came back down again, but it was still 600uH above the required inductance. I will do it like Don said using varnish as I'm winding the coil. I will also be able to take of a turn if need be. I also noticed that the shielding brings the inductance up by about 100uH so will keep that into account. How do you feel about leaving the TX coil unshielded?

Regards Xavier

[dfbowers]

My problem was that once the coil was glued the inductance went sky high then came back down again, but it was still 600uH above the required inductance. I will do it like Don said using varnish as I'm winding the coil. I will also be able to take of a turn if need be. I also noticed that the shielding brings the inductance up by about 100uH so will keep that into account. How do you feel about leaving the TX coil unshielded?

Regards Xavier

If you leave your coils unshielded, you will have all kinds of problems when you go to use it. Even a blade of grass touching the coil can cause a false signal, especially if the grass is wet.

[Davor]

My coil is centre-tapped balanced mode unshielded (FKK) coil and I have no problems with wet grass. This configuration requires a balanced Rx input which is very uncommon, yet if you make your own rig, you are free to configure the input the way you like it.

[6666]

Davor
would you mind sharing the schematic of your balanced RX input
if it is not too much trouble ?
Thanks