Menu
What's new
Find's Treasure Forums

Welcome to Find's Treasure Forums, Guests!

You are viewing this forums as a guest which limits you to read only status.

Only registered members may post stories, questions, classifieds, reply to other posts, contact other members using built in messaging and use many other features found on these forums.

Why not register and join us today? It's free! (We don't share your email addresses with anyone.) We keep email addresses of our users to protect them and others from bad people posting things they shouldn't.

Click here to register!

Need Support Help?

Cannot log in?, click here to have new password emailed to you

PI`s & Overhead power supply cables??

A

Anonymous

Guest
I know this is a general question, (Ive a PI which I`ve still yet to use in anger.., waiting for the right site & opportunity) but how does a PI handle interference from overhead supply cables? I^ve a couple of likely lakes that I`m hunting with a CZ20 in autotune because of the close proximity of pwr cables with a constant earbashing.Will a PI unit`s operation also suffer from the effects of a relatively close grid supply in the same way a VLF does?
I^m using a Barracuda btw.
 
Hi Eric, thanks for the info, I^m running a Barracuda which I`ve had for about 6 mths. I still havent raised the courage up to go out and use it yet to see how it performs, me being primarily a VLF man in the wet stuff.My idea was to work an area with the CZ and once the targets became less prolific return with the PI.That way I`d know most of the surface junk and easy targets would be gone and I`d have an easier time making my aquaintance with the Barracuda
 
<BLOCKQUOTE>A post above by Roy, mentions a coil with a figure of 8 receiver winding. This is very immune to noise. </BLOCKQUOTE>
Very True in killing electrical noise Roy...in addition and for fun,..
SD2200 Oddity for the day...
Wind a 1.75 meter radius coil with 8 turns into a Figure 8 mono using 30/0.01mm/ Litz. (who said it had to be in "spec" lol <IMG SRC="/forums/images/wink.gif" BORDER=0 ALT=";)"> )
Then, form the crossover gap between the coils into a 10cm (1/2 inch) circle, the area around this loop will activate the metal discriminator in the SD2200...similar to what a Double D does.
...maybe someone else here has the time to improve this aspect. <IMG SRC="/forums/images/biggrin.gif" BORDER=0 ALT=":D">
 
..oops, as per the above (where's the edit function in this forum? <IMG SRC="/forums/images/biggrin.gif" BORDER=0 ALT=":D"> )forgot to clarify.. it's <STRONG>6</STRONG> lengths of 8 turns of 30/0.01mm/ Litz. <IMG SRC="/forums/images/smile.gif" BORDER=0 ALT=":)">
 
Hi Gazza Do you mean 30/0.1mm litz wire ? because 0.01mm is getting down to the thickness of hair
Regards Frank Wallis
 
Hi Frank, yep I noticed a couple of "typo's" in my earlier post,(we need an edit function here <IMG SRC="/forums/images/biggrin.gif" BORDER=0 ALT=":D"> ) however considering the experimental nature of the coil the parameters were "close" enough.. <IMG SRC="/forums/images/smile.gif" BORDER=0 ALT=":)">
Here is the exact specs of the litz I used as indicated in the pic.
0.05mm @ 30 / 1.2 turns per inch.
.and yep, it's hair thin.. and ideal for making SD2200 probes. <IMG SRC="/forums/images/wink.gif" BORDER=0 ALT=";)">
The impedance of the coil windings I have indicated is way out of normal spec for a standard SD, however it was while doing one of my outer limit tests for the mods that I came across the effect.. you could possibly get the same effect using standard SD wiring specs.
The other typo is the 10cm loop where the crossover occurs, that should be 10mm..although experimenting with up to a 10cm loop may be another thing to try. <IMG SRC="/forums/images/smile.gif" BORDER=0 ALT=":)">
The discrimination wasn't as sensitive as a DD provides in the tests I did, however the idea of posting this was to see if anyone wanted to improve on this anomaly. <IMG SRC="/forums/images/smile.gif" BORDER=0 ALT=":)">
-gaz
 
drat......forgot to attach the pic again...lol <IMG SRC="/forums/images/biggrin.gif" BORDER=0 ALT=":D">
here's the 0.05mm @ 30strand / 1.2 turns per inch Litz.
 
I just had a close look at my earlier description on the wire set up I used, sorry about the confusion, I'll attach a pic here to make it clearer..
Basically it's 8 lengths 0.05mm@30 Litz of approx 14 metres in length , then twist all 8 Litz wires together and then wind the 14 metre twisted length 8 times around a 1.75m radius... then configured into a fig8.
Hope that makes it clearer.....
I found this Litz configuration is very good on small target sensitivity when used in a fig8 as the fig8 is prone to losses when used as a stand alone coil, but then remember this Litz wiring configuration is meant for a modified SD, however you could adjust the specs to suit a normal SD.
You may do better to wind a coil according to your standard specs using your own familiar wire for an SD, then test if looping open the crossover point works in a similar fashion.
Either way, here's what the Litz looks like when wound...
-gaz
 
Hi Gazza
I would say the DC resistance of the 1.75 mt coil be 7.0 ohms using that size cable?
Regards Frank Wallis
 
Hi Gazza
Got you now,in that case the DC resistance is about 0.3 ohms,and also you mean circumference,not radius.
Regards Frank Wallis
 
lol.gaawd ur right Frank, sorry...remind me not to post on weekends! lol <IMG SRC="/forums/images/biggrin.gif" BORDER=0 ALT=":D">
..good luck with the tests. <IMG SRC="/forums/images/smile.gif" BORDER=0 ALT=":)">
 
Hi Gazza
We are all guilty of making mistakes,I have made heaps,so just keep taping on the keys,a lot of the things that you say makes you think a little more about the coils,which are so important.
Regards Frank Wallis
 
Frank, here's the type of crossover gap setup I am refering to for the fig8 (in demo form).
 
Hi Gazza
There is no doubt about it a picture is as good as 1000 words.
Regards Frank Wallis
 
Frank, you're absolutely right about coils being a functionaly important aspect in detecting... (I'm not so sure about my typing and presentation skills on a net forum tho <IMG SRC="/forums/images/wink.gif" BORDER=0 ALT=";)"> lol )
Well performing coils are similar to having hi quality speakers in your top of the line sterio system, without them, you only hear "so" much. <IMG SRC="/forums/images/smile.gif" BORDER=0 ALT=":)">
-gaz
 
You must log in or register to reply here.
Top