Hand held pin pointer question

[moodybrk]

Hi,
Can anyone tell me where I can find a good schematic(s) for hand held pin pointers, I would like to build one to the size of maybe a white's or merlin hand held, plus I will need the to know how many winds to put for a small coil. Hope some one can help or point me in the right direction. Thanks
Moody

[rheslip]

Hi,
Can anyone tell me where I can find a good schematic(s) for hand held pin pointers, I would like to build one to the size of maybe a white's or merlin hand held, plus I will need the to know how many winds to put for a small coil. Hope some one can help or point me in the right direction. Thanks
Moody

I recently posted a P.I. pinpoint probe design in the "coils" forum. It works exceptionally well IMHO, but probably only practical as an add on to a Hammerhead or similar DIY PI unit. You could build the SMT hammerhead board and use this probe but its probably overkill.

Check out http://home.clara.net/saxons/probe.htm for a simple design using a PIC. Unfortunately no PCB, schematic or hex codes, you have to buy a kit. I've traced the board tho and it appears to work by detecting a small amplitude change as the oscillator coil nears metal. They claim 1" detection, which is believable based on what I observed while experimenting with the idea.

Rich

[Esteban]

Pinpoint

See September 89 Andy Flind's project - Everyday Electronics magazine.

[antonioknight]

My opinion build the barracuda and make the coil looks like printer in about 5-6 cm diameter
What do you say?

[Carl-NC]

The direct sampling PI design in my book would make a good pinpointer. Only has two 8-pin ICs (opamp and PIC) and runs off a 9V battery. Make the coil on a ferrite rod and it should pick up coins 2-3" out.

[antonioknight]

Carl isthis corrrect to use barracuda as pinpoint???

[antonioknight]

Creating a 5-6cm coil.???

[kt315]

My opinion build the barracuda and make the coil looks like printer in about 5-6 cm diameter
What do you say?

why Barracuda is your choice? there is not differences between Barracuda, Surf PI and Hammerhead in general and main. you can order SMT board from Carl directly, do not waste your time, and do the PP using the board.

[Davor]

I'd say this one is nice: http://www.geotech1.com/forums/showthread.php?19005
I thought of building it myself only in through hole version.

[Carl-NC]

Carl isthis corrrect to use barracuda as pinpoint???

As KT says any of the PI projects can be used for a PP design. The one Davor links to looks like a loaded loop design, similar to the Garrett ProPointer & White's Bullseye. Very simple design but generally limited to ~5cm distance. PI can get 10-15cm if that's what you need.

[antonioknight]

I see thanks men.

[Tibuck19]

The direct sampling PI design in my book would make a good pinpointer. Only has two 8-pin ICs (opamp and PIC) and runs off a 9V battery. Make the coil on a ferrite rod and it should pick up coins 2-3" out.

Good evening Carl, which PI would it be PI-1, PI-2 or PI-3 ??

[Carl-NC]

PI-4

[Tibuck19]

PI-4

lol But of-course the only one I didn't mention, any recommendations for the pic programmer, in your book you mentioned the 12f1840, do you still recommend that one, or is there a newer or more modern one you would prefer I get for it ?

[Carl-NC]

The 12F1840 was chosen for size (8 pins), fast internal oscillator, ADC, and sufficient memory. It only has a 10 bit ADC, a 12 bit would be better. There are Pics with 12b ADCs in larger packages.