EE Treasure Hunter

[arjoca mihai]

Hi,
I attempt to buid the Microcontroller PI treasure hunter by Mark Stuart and I notice mismaches between PCB and diagram ,coil must be connected at 9V, VR1 (100K pot) I'm not sure(at 9V or at 16v), anyway voltages are ok 16V and 5V
but when I want to test it I hear a tone in the headphones but I can’t vary the pitch of tone with VR1(see section TESTING in document stuart2.pdf) Also I take the
source code written for 16C84 (pi84.asm) and put in MPLAB IDE (Microchip tool) and try to build it (compile) for 16F84, errors appears ;
I don’t understand the comments in asm file, they are not written in english. I fogot to mention that I burned the hex file found on Carl’s page into a 16f84 because microchip don’t make any more the PIC 16c84 and can’t find it. Please help me with more information...
best regards,
Arjoca Mihai






Carl's site geotech

[Dan Golden]

Re: EE Treasure Hunter

The PIC 16F84 is a better choice as you can keep reprogramming it since it is a "flash" version. I gave up on Stuart's PI and made Gary's PI detector. It detects a 1 ounce coin at about 30 inches w/ a 15 inch coil. I converted it to be controlled by a PIC 12F675 (8 pin DIP) and it works great. Got rid of all the 555s. I made a new 24 inch coil and it detects a small tin can at 3 feet quite easily in air. I'd recommend you switch to the 12F675. They are less expensive (~$2 from Jameco) plus it has a comparator that you can put on the output instead of the 555's noise maker. I am using 2 12F675s, one on front end to drive coil and timing for collection and one on output to drive headphones. Works great! I still get best detection distance using a meter however.

[kt315]

Re: EE Treasure Hunter




some correction of the schematic was done by a buddy. i hope this will help..

[Reg]

Re: EE Treasure Hunter

Hi KT,

The factory board one gets from Magenta connects R3 to pin 6 of IC 2, rather than pin 5. Both should work, but connecting to pin 5 will effect the sample hold.

Reg

[Claude]

Gary's PI with a PIC is Dan's PI

Hi Dan,
Would you mind sharing with us the modifications you made to the Gary's PI?
Thanks,
Claude

[Kev]

Re: EE Treasure Hunter




Hi Arjoca,
Here's the schematic. Note C4,R26,R28b, and VR1 connection.
Cheers
Kev.

[Kev]

Sorry Arjoca, still mistakes !




Now please note: Coil connection as you are already aware and R27 - along with C4,R26,R28b, and VR1 connection
ta
Kev.

[Kev]

I don't believe it, yet another !




Sorry I sure hope it's right now. Note IC4 Pin 7

Along with Coil connection, R27, C4,,R26,,R28b, and VR1 connection all different from original.

Cheers
Kev.

[Kev]

This is embarassing. Faultless sch?




I should have looked more closely before uploading the first schematic, sorry about the space Carl.

Note: IC4 pins 2 and 3.
Pin 2 is the inverting input not 3

Added to changes on the schematic from the Stuart 2 PI construction pdf
IC4 pin 7, Coil and VR1 connection, R27, C4, R26, R28b,

Cheers
Kev.

[Gary]

Re: Gary's PI with a PIC is Dan's PI

Hi Claude, It doesn't make my unit anymore sensitive with the PIC, just maybe a bit smaller board.

Using a Digital meter rather than an analogue neter, dramatically increases the sensitivity because of the ability to see very small changes.

Gary

[Nelson]

Re: Gary's PI with a PIC is Dan's PI

Hi Dan,
Would you mind sharing with us the modifications you made to the Gary's PI?
Thanks,
Nelson

[nba]

100H

In this post, "http://thunting.com/geotech/forums/showpost.php?p=29089&postcount=3" the attached schematic shows C17 as 100H.
Someone maybe convert that into uf,pf or nf?
tia

[kt315]

In this post, "http://thunting.com/geotech/forums/showpost.php?p=29089&postcount=3" the attached schematic shows C17 as 100H.
Someone maybe convert that into uf,pf or nf?
tia

100 nF=0,1 uF

[RexK]

Microcontroller PI Treasure Hunter Corrected Schematics

Hi Arjoca,
Here's the schematic. Note C4,R26,R28b, and VR1 connection.
Cheers
Kev.

Kev
Does your schematic reflect changes? I plan to build a treasure hunter using proto board(s). I noticed that the article schematic and PC board disagree (+9 & +15v feed). I have scanned through the forum and found list of changes that are a little vague. Could you send a copy of your revised schematic?
Thanks in advanced
Rex