PICKINI - an easy to build PI detector

[bernte_one]

i have finished my pickin from post 200
works
but have to make right coil and make sound a little bit louder


thanks all for posting results

[F117]

Looking forward to some pictures of Your build, Bernd

Best regards,
- Bernard

[bernte_one]

made first test today, coil from older surf pi project around 290µH, 27cm diameter and copper tape shield

must say wow

2€ coin 25cm in air - that is ok
but also small 5*10mm 0,39gr. gold nugget around 2cm
bronze buckel over 35cm

clear detection like principle hole or nothing
can stay over target for pinpoint- tone stays

no trouble with tuning pots or trimmer

switch on and go

im going to set right damping value for my coil but feels like it is already in right area


was fine work
Bernard

[F117]

2€ coin 25cm in air - that is ok

The 1, 2 and 5 eurocent coins may even give better results, since they are iron coins with a copper coating.
On the beach, I find a lot of these since most "more sophisticated" detectors will discriminate them.
Since the 1 and 2 eurocents will disappear gradually, they may become collector's items !

Best regards,
- Bernard

[farafero]

I apologize for asking this scheme chips (integrated circuits) have to be programmed?

[F117]

farafero,

yes, You need to buy the Microchip Pic microcontroller and program it with a hex file available here : http://users.telenet.be/willaert/MD/.../software.html
or have it programmed at your local electronics shop.

Best regards,
- Bernard

[Waikiki_Sweep]

To program the PIC, I use the PicKit3 USB programmer
http://www.microchip.com/stellent/id...irects=pickit3

Who can point to cheap way to program PIC? For example to program Attiny I am using USBASP programmer ($2.70 on ebay, ships free from China) + Khazama AVR Programmer software (free).

PicKit3 USB has been offered by Microchip for $45 and that is unrealistically high price.
There should be a cheap alternative I hope.

...

I have found one USB PIC Programmer for $10
http://www.ebay.com/itm//200944364396
Hope it works.

[6666]

Do yourself a favor and buy a real microchip pickit, there is a thread I started here on the problems with cheap imitations.

There are 2 pickit programmers, you have to look very carefully to see which one will program the chip you want to program.

I have both, so I can program the whole range of pics.


For AVR I use 4 resistors.(10 cents)

[Waikiki_Sweep]

For AVR I use 4 resistors.(10 cents)

"AVR Serial Port Programmer" Good idea! It have to be included straight into Chance PI schematic.

[bernte_one]

what kind of speaker should be used
i tested some miniature loudspeaker (non piezos)
but they are not loud enough i have also removed the 1K resistors before the audio output
but this results in constnat tone when settignthe sens to 50% and higher

had also tested a small piezo which was removed from an old electronic toy (not all types work)
sound was also not loud enough

last solution would be to connect an 3,5mm headphone connector and use headphones but i dont like headphones for beachhunting in the summer

[F117]

The cheapest earphones you can find are sufficient - small in-ear phones, since the sound is digital (tone or no tone - just a one second tick).
As "real" loudspeakers I once used a 50 ohm speaker from a telephone - not the one in the horn, but the one used when the phone is on speaker. Something like this:
http://www.conrad.com/ce/en/product/...aker-50-360-Hz

With good headphones, I normally use a volume control to reduce the sound level as it is too loud.

but this results in constnat tone when setting the sens to 50% and higher

This points to unstability - once the sensitivity is set too high and disturbance signals are picked up.
Inside the house I can only turn up the sensitivity very little -- outside, away from interference, you can crank up the sensitivity.

Best regards,
- Bernard

[bernte_one]

i tested the but only loud enough without the 1k resistor

http://www.conrad.de/ce/de/product/7...-1-St?ref=list
http://www.conrad.de/ce/de/product/3...-1-St?ref=list

but seems that i have to leave my house , and the problem with false signals without the 1k resistor will remove

thanks bernard

[satdaveuk]

Build a simple 1 or 2 stage amplifier for it using a 2-3 transisitors , dont try using a chip as they all seem to have AGC built into them which is no good with these projects.
Will work a universal type amp out later today for you all.

Regards

[bernte_one]

long time ago i write over a simpler headphone amp something like a one channel cmoy
but i think it is too much

a simpler solution is better
hope for your design soon

thanks

[satdaveuk]

Power Amp

Hi
Can one of you here please tell me what the output power is in normal use in presents of metal and output without detection and then maximum output.
Also like to know optimum output impedance if possible.
Just measure with volt meter across audio output terminals and set scale to 500mv or so, then I can get started working out something very easy and simple.
Thanks
Regards Dave