IDX-PRO+VDI

[Koala]

Thanks golfnut makes sense.If there is a solvent that evaporates the the partials will be forced together

I have fiberglass around the windings to make two very strong D shaped rings.

Was hoping to fiberglass the two together at the null point. Then use card with the graphite mix top and bottom.

Would this work or does each need to be separately shielded

[Silver Dollar]

I have a similar question. I'm building a PI coil using the insides of a coax. I stripped off the shielding
except for a foil wrap. I could wind it with the wrap on and use that as a shield or remove it and do the
shield on the inside of the housing. Which would be better?

I think graphite makes a good resistive shield and have painted it on a cloth tape wrapped coil and also
used it on the inside of a housing. Both seem to work fine for VLF, I use the graphite paint from tractor
supply...

[Koala]

I have a similar question. I'm building a PI coil using the insides of a coax. I stripped off the shielding
except for a foil wrap. I could wind it with the wrap on and use that as a shield or remove it and do the
shield on the inside of the housing. Which would be better?

I think graphite makes a good resistive shield and have painted it on a cloth tape wrapped coil and also
used it on the inside of a housing. Both seem to work fine for VLF, I use the graphite paint from tractor
supply...

Can't answer for a PI but for a for the IDX I found the space blanket wrapped around the TX and RX worse than no shield at all. Tried many different ways no joy


Did see somewhere that Eric Foster got the best result by rapping the bundle in double sided tape and then spiral wrap
ribbon cable around the bundle.


Edit

Found link http://www.findmall.com/read.php?34,1174380,1175238

[Schatztaucher]

hi guys,

need again help of the guru`s. yesterday I built the 2 ton board of eduardo. so far everything works ok. the non-ferrous ton is loud, clear and high sound. the iron-ton is a deeper tone. but somewhat scratchy and very quiet.....
can anyone tell me why this might be?

King regards, marc

[golfnut]

Put decent picture on

[Koala]

Seem to remember someone else having the same problem a quick search of the thread failed to find it.

Also remeber the two tone did not like some ground conditions

[fluxx]

I have made a few photos of my IDX, that is work in progress. It's finished, but still untested. Now on to coil building (oh, boy, this is going to be fun). Wish me luck.
http://i.imgur.com/OlAnNl5.jpg
http://i.imgur.com/YsSxZ1p.jpg

[6666]

Hey Fluxx when you finish soldering, carefully clean all that flux off the back of the board.

[fluxx]

Thanks for advice. I have personally never left flux on the PCB, but my father considers it to be protection from oxide. Of course, he doesn't use flux, but rosin, and hasn't had problems. I however prefer to clean it and spray it with shellac, which I find works better and doesn't oxidize the copper over time, like rosin supposedly does.

[jlsilicon]

Well, I finally got in an Induction Meter and tested my Coils :
TX: 35mh
RX: 530mh

Considering they should be :
TX: 35.6mh
RX: 0.587mh

(Obviously I will add windings to fix this)

Is this enough Error to cause Random Noise Interference ???

[Qiaozhi]

Well, I finally got in an Induction Meter and tested my Coils :
TX: 35mh
RX: 530mh

Did you mean 530uH?

[Koala]

Well, I finally got in an Induction Meter and tested my Coils :
TX: 35mh
RX: 530mh

Considering they should be :
TX: 35.6mh
RX: 0.587mh

(Obviously I will add windings to fix this)

Is this enough Error to cause Random Noise Interference ???

Asuming a typo. then close enough. Most random noise is due to the coil shield or windings not glued together.

[jlsilicon]

How about mounting the Board and POTs in a Plastic Box ?

Maybe this can create noise after a minute from the static ?

[golfnut]

Ideally it would be screened box, - because the pcb has no GND plane.

[scrungy_doolittle]

Fluxx, did you do the board yourself?
I just ordered 2 idx boards and a TSGL and a hammerhead D from Andy over at silverdog.uk. One board is going to be built stock, the other is going to be a development board. I'm starting on a hybrid detector (analog and digital).
Full featured VDI is going to be the first step. I have a 6B coil on my 5900 and one on my 4900, so I want to build the idx to work with those coils.
The frequency generation is going to be done by the MCU (I'm going with a PIC24FJ128 something. Not sure whether the 44 pin will have enough pins, but I think it will.) The VDI will have enough features to let it function as a good deal more than a simple VDI, though it can be built that way. Working on pin assignments at the moment. Will support 8 bit parallel LCD display, 4 analog in's, two analog outs, 2 builtin comparators in the PIC24, and 4 control signals out for the sampling circuits. going to get rid of the ground balance and disrimination phase shifters, and just use a time delay triggered off the rising edge of the transmit frequency.