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Optimum Depth coil size for GoldPic3?

A

Anonymous

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I am ready to build the coils for my Trevor Hill GoldPic3 and need your help soon. I hunt exclusively for gold nuggets and since the first 12" of soil have been pounded by guys with Goldmaster 4b's,Minelab 17000's, etc., what I'm after are the larger nuggets that lay beyond that depth. There have been nuggets as large as 4 ounces found in the not too distant past so I know they're there. I know Eric you recommend rectangle shapes. So I need size's for a mono and a double D (14" of larger?). Also on the Double D, what would be the optimum spacing between the coils?
Thank you so much Gentlemen for your kind assistance!
Randy Seden-Simi Valley,CA.
 
Hey Randy,
It's me again. My Gold Pic kit is on the way as of Wed. the 17th. Any suggestions on where to obtain parts? Will be most interested in the coil building aspect of the Pic as this is uncharted territory for me. Any hints, tips, suggestions, etc. most welcome.
Regards, RD, Indio
 
Richard,
Ok, warm up your printer here goes. The hard to find IC's I got from JDR Microdevices as follows: 1-74HC4066(59c),1-ICL7660CPA($1.29),1-LM318(79c),1-ADC-0831($1.89),1-4.0 MHZ HC-49 xtal ( 99c),and 1-78L05 (19c)and the c stands for cents. JDR Microdevices is on the web and their phone # is (800)538-5000. Far as the resistors and caps, I got them from DC Electronics (www.dckits.com)or (800-423-0070) and the pots came from Mouser electronics (800 346-6873) and finally,the LCD display came from Digikey Electronics and it's a "Optrex" model DMC16230 which will set you back $19. By the way, the 74HC4066 is Philips Semiconductors new improved version of the ol' 4066 and is highly recommened that you get this version. So that's it for you and anyone else that decides to get this well designed PI unit (Trevor spent 2 years of Midnight Engineering on this as he uses it regularly on the beach near his house finding all kinds of rings and coins the folks staying at the local beachfront motel leave behind). I'll let the group know how this unit works for Gold nugget hunting as it's a lot cheaper than a minelab.
Randy Seden-Simi Valley,CA.
 
Hi Randy,
Thanks for the info. Just copied it out. It will come in very handy for me. I'm an old nugget hunter myself so it'll be fun comparing the Gold Pic with my LST, SD2200 and GM V/SAT. I suspect it will do well except in the very highest mineralization. We'll see. Check out my column on nugget hunting on the Treasure Depot when you get a chance. My picture will be on the next cover.(Lord help us!) Regards. RD,Indio
 
Hi Randy,
I have a Goldpic kit on the way and if you can hang on, I will be able to give some tested answers. Off the cuff, I would try 14in x 4in for a mono winding and two 14in x 4in windings for an overlapped DD type. The amount of overlap is best done experimentally.
Eric.
Eric.
 
Can anyone help with info on the GoldPIC3? The web address I have for it is no longer valid and I have had no response on an email inquiry regarding the kit. I would like to order it but am not having any luck. I'm glad you are getting one Eric, It will be very interesting to see what you think of it.
Thanks, Charles
 
Hi Charles,
E-mail me at rmdelahanty@cs.com and I can put a link on my mail for you. My GoldPic web side is still opening in my list of favorites so you should get it OK. RD, Indio
 
Hi Guys, I will give what I know on the Goldpic3.Parts: Vikay 2035 TNLDNOTW-D 2x16 character led backlit STN $8.00 at Earth Computer Tech www.flat.com/character.htm HSC electronics 1-800-442-5833. Get the catalog. These parts may not be listed, but they have big amounts of these chips. LM318, 7660,4066. Nuts and Volts mag. has the add on the second page. Digit-key has the ADC0831,IRF740 and the metalized cap(1uf). Transistors- BC550C= BC109C,2N930, NTE199
BC560C=BC559C, 2N6007,NTE234 The coils I have made by the instructions: 7.5= 400 to 436uH, 1.5 to 1.6 ohms. Adjusted with resistors on the circuit boardl. I made the rod because of budget. I put the zero switch on the rod and the control box. It makes it alot easier to zero adjust when detecting. Also have a battery pack on my side 12v 7A gel cell. I bought a camera bag at Wal-Mart for about $10.00 that fits just right with belt loop and shoulder strap. Also I have e mailed Trevor Hill on the subject of dual coils. He said with twin coils use the existing coil for the Rx and "disconnect the drain lead(middle pin) to the MOSFET power output transistor to route that via a transmit coil to bat +." It is better to make corrections or twicking on board before you assemble your detector. I also like that others are now getting envolved with the goldpic3. I will be making a 14x4 inch mono as soon as I can. 14" coil means sthat I make a 14" coil, then compress the equally on both sides to 4". This makes a oval shape. Codrrect me If I am wrong. Still learning alot about PI and electronics. Pin 12 of the PIC should be at +5v and pulse to 0v for 200us every 4ms. Thats about it for now. I will be watching. This forum is good active one. Rick S
 
Well, I found the website for the Goldpic3, his webjump mirror site is what I had bookmarked and is gone. Is this an original design or is it just a modified version of the PIC based kit by Mark Stuart which is posted on Geotech site? I haven't seen the schematic but looking at the parts list it seems awfull close to the same parts called for with Stuart's unit. If anyone has the schematic of the goldpic3 in GIF form that Trevor emails I would appreciate a copy, I haven't had any luck getting it from Trevor. Thanks, Charles
 
I have enjoyed previous discussion with Trevor Hill, and because of the difficulty that some appear experiencing in contacting him or his site, I am sure he will not mind me sharing our correspondence.
He, like me, had difficulty with Stuart's design, but made the effort to start anew as it were.
Trevor pointed out that Stuart used the PIC solely for timing. No doubt with a lot of effort hearkened to on another site) Trevor's PIC use now encompasses -
1. Drives the output dwitch timing 2. Drives the sampling gate timing 3. Reads and controls the Analogue/Digital converter 4. Drives the LCD display (numerics and bargraph 5. Reads user input from the "zeroing" pushbutton 6. Extracts the detection signal from the rather
noisy target signal 7. Provides the silent search mode by reading and
setting the target threshold 8. Drives the audio output to the headphones
Trevor deserves every praise, but I am just starting to wonder whether he is aware of this site.
I had no difficuly in downloading the schematic, but this was in January.
g
 
In the past I have had no problem talking to Trevor Hill.His address is:
Trevor R. Hill
2 Jefferson Rd.
Claremont
7708, Capetown, South Africa
www. Trevor Hill<trh@global.co.za>
 
Hi All,
I have just 'found' this site after receiving an e-mail and link from Eric.
Both my web sites are up and running, but due to bandwidth limitations they can be slow at some times of the day. The URLs are:
http://home.global.co.za/~trh (the main site) http://goldpic.webjump.com (the mirror in the USA)
I am mailing a GoldPIc semi-kit to Eric this morning.
Thank you to those who have kindly answered queries on my behalf and passed on addresses and information.
Trevor.
 
Hi Trevor,
The Goldpic kit arrived this morning. Many thanks.
I've started ordering some of the parts that I don't carry in stock but came across a small problem. Farnell (parts supplier) said that the ADC0831 was now obsolete. What alternative should I use?
Eric.
 
Hi Eric
I am not sure but I do think I have a tube of ADC0831 somewhere. I will look for it one of the following days and will be glad to send you a few for free. I will let you know if I find them.
Mark
 
Hi Eric,
National Semiconductor list the ADC0831 as still being in full production. See http://www.national.com/pf/AD/ADC0831.html#Availability
There is also a new improved version, the ADC08831 (8 Pin version) that is an improved pin compatible replacement for the ADC0831. (This new device goes into a low power mode when a conversion is not taking place.)
If you have problems finding one, send me an email and I will mail one to you.
Trevor.
 
Eric,
Another equivalent A/D converter for the GoldPic3 is the TLC0831CP from Texas Instruments. (Manufacturing status: ACTIVE)
Micro Linear also produce an ADC0831 equivalent, but unfortunately I do not have the number for their device.
The Linear Technologies LT1096 should also work as another alternative.
Trevor.
 
Hi Trevor and Mark,
Many thanks for the help. I will try some other suppliers and also look for the alternative parts. I'll come back if I still have problems getting one.
Eric.
 
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