IDX-PRO+VDI

[golfnut]

It is the pull up resistor for the mos switch for the PP .

Dont know what layout version that is, the 100k used to be next to the two PP wire holes and the resistor had to be mounted vertically to fit in. S

[Koala]

It is the pull up resistor for the mos switch for the PP .

Dont know what layout version that is, the 100k used to be next to the two PP wire holes and the resistor had to be mounted vertically to fit in. S

It's a very early board.

The resistor under the socket was moved in post 10

Without read through the thread again can't think of any other changes to the layout until the recent ones.

[paku]

ok is that final version i download from here
hahaha

[golfnut]

Get a board from silverdog, it will save some of your life

[paku]

Get a board from silverdog, it will save some of your life

(facebook) Like

[ossamaussama]

mu idx is tuned by 18 nf capacitor so it can reject frite ? why when i use 30--32 nf get good depth but cannot reject frite

[paku]

what coil your ar using

[ossamaussama]

home made coil 27 cm

it tuned only with 33nf if i swapped TX wire very deep result for coin 45 cm but cannot reject frite
what is the correct connecting for coil?

[paku]

you make your one board you buy from silverdog

[ossamaussama]

my own board

[golfnut]

1 If you can now reject ferrite using GEB control.
2 Then Try small clean iron - reject this with Disc.

3 Now try gold bronze silver etc

If all good then your done.

If you don't have the depth you require


Move the Rx cap value up or down . Now you have better air test RE DO 1,2,3 to confirm whether the phasing is still good.


If you have a pcscope you can SEE where the signals are IN TIME and the Tx signal and the preamp out signal should be 180deg out of phase wrt to each other.


You should build as design and get initial phasing right by moving Rx Tx coil in the housing

[golfnut]

Minor typo in Dons post..

"36uF max" should read 36nF S

[Koala]

home made coil 27 cm

it tuned only with 33nf if i swapped TX wire very deep result for coin 45 cm but cannot reject frite
what is the correct connecting for coil?

Doughnut shape ferrite can't be used for testing. Solid rod or small fragment work well. I get just under 40 cm air test with a 27cm DD but that's unstable when tested over real soil. Better slightly less depth but stable in use.

[Valters]

Now one beginner question.
In my first IDX I use MKT +/-10% type capacitors, now I will try second one.
Is sense to use FKP +/-2,5% (3x time expensive that 5% and 10x than 10%) type capacitors or it is enougt with +/-5% MPF type capacitors or even 10% MKT?

[hoadlies]

My project of the week..
http://www.youtube.com/watch?v=buU4h2QpgOw
I wanted to see how cheap I could build an 8" coplaner coil for IDX. Turns out, under $20.00! I did have to break out the vacuum forming machine. This was not an easy project compared to a DD coil as tuning was a little tricky between the Tx coil and the bucking coil.

Start with a sheet of 1/2 inch foam board from a craft store - It's "large cell" foam, that is somewhat brittle but also stiff.
It is cut into a donut shape to accept a spool for the Rx coil.
The Rx coil is wound on a homemade spool of cardboard with a foam center.
The foam "donut" is then glued to a sheet of stiff cardboard and the Rx spool is glued into the center.

The Tx coil is made on a separate former and held together with Cyan glue. Then this coil is simply glued into a channel cut into the foam. The bucking coil is wound opposite the direction of the Tx coil - directly on top of the Rx coil.
After tuning and nulling, the inner ring is filled with slow cure epoxy.

Rx coil - 3.25" - "about" 425t for 34 AWG wire (35 mH) wound counter clockwise + 33nF cap
Tx coil - 7.5" - 34t for 22 AWG wire (583uH) wound counter clockwise + 1 uF cap
Bucking coil - about 11 turns wound on top of Rx coil wound clockwise

For the best null, the hot end of the Tx coil must be connected to "Tx start" (P8 pin 1)
The grounded end of the Rx coil must be the wire closest to the bucking coil - " Rx end" (P8 pins 3 & 4).

For the tricky part - When the bucking coil is wound around the Rx coil opposite direction from the Tx coil, the frequency goes up by about 60Hz, so a turn or 2 will have to be added to the Tx coil to bring the frequency back down to 6.59kHz.After tuning and nulling, the inner ring is filled with slow cure epoxy.

For shielding, I used heavy gauge paper, covered with graphite powder from the hardware store. I just dumped some on the paper and rubbed it in until I got a conductive sheet of paper. The paper ended up with about 35k Ohms of resistance across the entire sheet yet is not detectable by the coil. A drain wire is then attached with masking tape and a bit of conductive glue made from a slurry of rubber contact cement and epoxy. Amazingly enough, rubber contact cement can become conductive if enough graphite is mixed with it. (maybe someone can comment on the effectiveness of this practice, but I can demonstrate that it does work).

For a cable, I just used Belden 8723.
Enjoy!
Don

HI DON ,, I find your Coil Building Posts very informitive ,As I am New to this hobby, Thankyou for your Sharing of your Builds ..

I find the AWG,SWG wire size guages very confusing ,But I found a conversion Chart thats helped ,,
WOW- 0.020 mm wire is very thin ,Do you find it hard to work with????,Also in AUstralia its not easy to find those Guages of wire in small rolls ..
QUESTION ,, how critical is the wire Guage ,in your opinion ???? Is it more important to get resistance value & or mH values ..
IS it possible to use thicker wire in the RX windings Be-it DD & or Coplaner ???? such as 0.24 mm..

I have a lot to learn here as I have Just gotten into this hobby..



CHEERS ,,BARRY..