IGSL

[der_fisherman]

Yes, Henrys and Farads and frequency in Hz are the units.


I believe the two caps in the oscillator are combined in parallel, so both do affect the oscillator frequency. I think the oscillator frequency is approximately equal to:

1 / (2 * pi * sqrt(L * C))

where L is inductance of TX coil and C is C1 || C2 == C1 * C2 / (C1 + C2).

To adjust, I'd probably focus on the larger cap by either replacing it and/or add small caps in parallel, depending on whether you want to adjust the freq up or down.

Probably adding small caps across the TX coil leads would work too to lower the freq.

I probably confused people by talking about C6 in the RX resonant circuit, because in IGSL circuit Ivconic relabeled it to C4. In any case, I mean the .015u capacitor connected in parallel with the RX coil.

I don't see a C43 in the IGSL circuit... which do you mean?

Regards,

-SB

In the schematic that I have, there are two caps shown parallel to the Rx coil......I may have the wrong schematic, at one point things were getting changed more often than a whorer's underwear......
It may be a good idea to ask here of SilverDog, which schematic did he finally use? Hey SilverDog!!!!
Also to ask Ivconic, what he considers to be the final version (probably only for now knowing how quickly he works!!)
Regards
Andy

[der_fisherman]

Ask Georgi Zhelev who sell coil housing here on Geotech. I am pretty aware that he can offer other building parts (as enclosure (box), and pole assembly) too.

That sounds very interesting if the price is right!!

[silverdog]

I used the versions posted early by Ivconic which were deemed Final.

Yes there are 2 caps in parallel with RX, namely C4,C43

I have looked at the problem of decent but affordable coils and shafts, a major problem once found would be shipping costs.
Shafts are not too expensive to have made, but postage would not be easy or cheap.
Coils will be quite expensive to have made, but would be a bit easier to post.
I fear we need a source in each region, or a source with regional distributors holding stock, but we are mostly poor amateurs, who would risk making a batch and posting to various regions, hopefully to eventually recover costs ? probably no-one

Unless we have a rich member somewhere

[simonbaker]

I used the versions posted early by Ivconic which were deemed Final.

Yes there are 2 caps in parallel with RX, namely C4,C43

I have looked at the problem of decent but affordable coils and shafts, a major problem once found would be shipping costs.
Shafts are not too expensive to have made, but postage would not be easy or cheap.
Coils will be quite expensive to have made, but would be a bit easier to post.
I fear we need a source in each region, or a source with regional distributors holding stock, but we are mostly poor amateurs, who would risk making a batch and posting to various regions, hopefully to eventually recover costs ? probably no-one

Unless we have a rich member somewhere

I guess half the fun is seeing what you can do with a broom handle, frisbee, and Altoids tin...

[simonbaker]

In the schematic that I have, there are two caps shown parallel to the Rx coil......I may have the wrong schematic, at one point things were getting changed more often than a whorer's underwear......
It may be a good idea to ask here of SilverDog, which schematic did he finally use? Hey SilverDog!!!!
Also to ask Ivconic, what he considers to be the final version (probably only for now knowing how quickly he works!!)
Regards
Andy

(don't hit backspace after an emoticon, it deletes the reply you've been working on for 20 minutes...)

Ok, located the final version schematic... yes, those two caps function as one, so you can trim by adding or removing capacitors in parallel. I think sometimes Ivconic puts two parts so one can be used for trimming (as well as getting the value he wants). I like to put a socket for one of the caps so I can tune to my heart's content.

One thing I've learned is that all the tuning in the world is for nought if your workshop has a high noise level like mine does. So I'm somewhat stymied these days. I'm thinking about maybe making a big Faraday cage to experment in... just worried what would happen if Faraday escaped... well, if it doesn't work out, I can always donate it to the guy living under the overpass who thinks the Russians are listening in on his thoughts... wait a minute, that's me...

...tinker on.

-SB

[bernte_one]

got my kit yesterday

thx silverdog

now i will have some long nights, videos and pictures follow next week i hope

[ivconic]

C4,C43....
Yes, second one is there to trim if needed. Adding socket on it's place is good idea.
There is always variation, because very often i can not obtain high quality components with minimal tolerance.
That's why is better to have spare place on pcb.
"Last" version is the one Silverdog sent me, i like that one.

[der_fisherman]

I guess half the fun is seeing what you can do with a broom handle, frisbee, and Altoids tin...

LOL!

[der_fisherman]

(don't hit backspace after an emoticon, it deletes the reply you've been working on for 20 minutes...)

Ok, located the final version schematic... yes, those two caps function as one, so you can trim by adding or removing capacitors in parallel. I think sometimes Ivconic puts two parts so one can be used for trimming (as well as getting the value he wants). I like to put a socket for one of the caps so I can tune to my heart's content.

One thing I've learned is that all the tuning in the world is for nought if your workshop has a high noise level like mine does. So I'm somewhat stymied these days. I'm thinking about maybe making a big Faraday cage to experment in... just worried what would happen if Faraday escaped... well, if it doesn't work out, I can always donate it to the guy living under the overpass who thinks the Russians are listening in on his thoughts... wait a minute, that's me...

...tinker on.

-SB

LOL!!
You are on a roll today, I like it!!!

[der_fisherman]

Tuning Tx to Rx Coils

C4,C43....
Yes, second one is there to trim if needed. Adding socket on it's place is good idea.
There is always variation, because very often i can not obtain high quality components with minimal tolerance.
That's why is better to have spare place on pcb.
"Last" version is the one Silverdog sent me, i like that one.

Its good to know that Ivconic and Silverdog were using the same schematic, though that would not have been a "big deal" to change either if needed, we should be flexible enough for that.

I did some coil frequency calculations last night and although the transmit appears to be about right, I calculated 13.429 KHz, the Rx resonance was far, far lower at 9.xx KHz, I forget what it was exactly, that does not seem to be the "1.1" difference we talked about.

I checked with each of the Rx caps seperately and together....it did not make a significant difference.....always 9.x something KHz.

Of course I may have made an error with my calculations/calculator......I am not perfect, but can anyone help me here.....? Thanks in advance.

Maybe that IS the best resonant frequency, only Ivconic can say for certain....I do remember him posting something about this (I think!), but could not find it.....

I feel that it would be great to have a method to tune the coils to each other for maximum sensitivity....after nulling of course....maybe even to allow even coils that may not be perfect in value (I hope to hell I know what the hell I am talking about here!!).

What do you Guys think? Am I asking the impossible? Is it a stupid question (or two)?

I have only seen setups for almost perfect coils (one of mine is slightly off in impedance when it was finished), but something inside me tells me that "tuning" should be an answer. I did like the idea of a socket for tuning that Ivconic recently mentioned, I will do that....

Regards

Andy

[der_fisherman]

I used the versions posted early by Ivconic which were deemed Final.

Yes there are 2 caps in parallel with RX, namely C4,C43

I have looked at the problem of decent but affordable coils and shafts, a major problem once found would be shipping costs.
Shafts are not too expensive to have made, but postage would not be easy or cheap.
Coils will be quite expensive to have made, but would be a bit easier to post.
I fear we need a source in each region, or a source with regional distributors holding stock, but we are mostly poor amateurs, who would risk making a batch and posting to various regions, hopefully to eventually recover costs ? probably no-one

Unless we have a rich member somewhere

I do like the idea of a custom made shaft and box, but coils may be a problem as there are already suppliers of coils around, none cheap thats true......but if you could supply well made.....I may change my mind completely, it does cost us hours of work...but a good result is achievable for DIY coils....but shafts? No....

Its good that you are considering the transport costs early.......but do let us know how you get on, a proper shaft and box would be great. Professional looking.....it would be sad if the Transport costs killed that......it's something that is simply missing.....

If its cheaper to send say 5 at a time to a particular country, maybe we could "club together" in each country and buy together....or something...I may be on my own here in Gerrmany though.....sadly!

I am looking around to see if I can find a substitute for the shafts in different stores, the best to date is an extendable wish mop....but I will let you know if I strike lucky......

Regards

Andy

[bernte_one]

...If its cheaper to send say 5 at a time to a particular country, maybe we could "club together" in each country and buy together....or something...I may be on my own here in Gerrmany though.....sadly!


Regards

Andy

sure not andy we know us from other german forum you are not alone
and there are other member from germany too forexample user compadre - his tgsl is running know but i think he will work on in diy projects here

if have nothing against to build a buying group but problem is whom you can trust
for a known user here it is no problem but often there are single posting users here which take a project out a gave nothing back
for such people a pay atttention they have no community thinking

but thats a theme a new thread

at the buy sell thread i asked user georgi for full list of his parts if i order something i had no problem to order some parts more i gave them away for replacement of my costs some times you will have also a minimum quantity for an order in such cases it would be possible to

greetings

[simonbaker]

Its good to know that Ivconic and Silverdog were using the same schematic, though that would not have been a "big deal" to change either if needed, we should be flexible enough for that.

I did some coil frequency calculations last night and although the transmit appears to be about right, I calculated 13.429 KHz, the Rx resonance was far, far lower at 9.xx KHz, I forget what it was exactly, that does not seem to be the "1.1" difference we talked about.

I checked with each of the Rx caps seperately and together....it did not make a significant difference.....always 9.x something KHz.

Of course I may have made an error with my calculations/calculator......I am not perfect, but can anyone help me here.....? Thanks in advance.

Maybe that IS the best resonant frequency, only Ivconic can say for certain....I do remember him posting something about this (I think!), but could not find it.....

I feel that it would be great to have a method to tune the coils to each other for maximum sensitivity....after nulling of course....maybe even to allow even coils that may not be perfect in value (I hope to hell I know what the hell I am talking about here!!).

What do you Guys think? Am I asking the impossible? Is it a stupid question (or two)?

I have only seen setups for almost perfect coils (one of mine is slightly off in impedance when it was finished), but something inside me tells me that "tuning" should be an answer. I did like the idea of a socket for tuning that Ivconic recently mentioned, I will do that....

Regards

Andy

What is your RX coil inductance and values of capacitors?

And TX coil inductance and oscillator caps too?

-SB

[ivconic]

How about adding this to IGSL:

http://www.youtube.com/watch?v=smie7...eature=related

[simonbaker]

How about adding this to IGSL:

http://www.youtube.com/watch?v=smie7...eature=related

I like it -- makes perfect sense, maybe we'll finally get the respect we deserve while MDing... just wear bright orange so you don't get shot at by real hunters...