PICKINI V4 - an easy to build, self adjusting PI detector

[F117]

Yes, when I press it, the PIC resets. I'm going to trace the entire circuit out and see if I have a bad solder joint. I'll report back what I find. Thanks for your help.

Check your programmer settings: the pinpoint pin (input only) is actually the MCLR of the PIC, which should be disabled when programming.
Check the thread - there are some screenshots of the programmer settings.

[morganton]

Check your programmer settings: the pinpoint pin (input only) is actually the MCLR of the PIC, which should be disabled when programming.
Check the thread - there are some screenshots of the programmer settings.

Yes! You were right about that. "MCLR Pin Function Select" was enabled. I disabled it, matched your other recommended settings and recompiled the code. I'll reburn the PIC and continue checking my circuit. I don't think I'm too far away from getting it to work.

[morganton]

Success! It works! It detects my pocket knife at about 8" and a quarter at about 4" with one of my coils that is unshielded and not optimized for this detector.

The pin pointer works the way it should now too. No more resets.

But, the voltage for LM318, pin 5 is still over 8 volts, so something is still wrong. Any ideas?

My batteries are down to 11.5 volts so I will get some new ones tomorrow (or should I say today).

[Arionas]

BS170 connections on my original schematic
http://users.telenet.be/willaert/MD/..._schematic.png

D: R10 = 4k7
G: R21 = 10E
S: GND

[F117]

I wouldn't worry too much about pin 5 of the opamp for the moment. It is not connected anyway.
Charge the battery to 12V, take the detector outside the house -away from EMI and metal - and switch it on again there. Sensitivity should be better.

[ripsdevala]

What is the maximum battery voltage for pickini 4? can i use double 9v battery?

[F117]

The optimal voltage is 12V.
I never tried it with 18V. The limitation will be the automatic adjustment range = offset of the opamp.
You can try it, but I would not recommend 2 x 9V blocks in series. These 9V blocks have very little capacity - they are made up of smaller cells in series.
10 x NiMH(12V) or NiZn ( 14 - 15V) or 3x LiIon is ideal.
These 9V blocks are insufficient ( capacity wise). They will work for only a short time:
http://www.astoriasoundworks.com/product/duracell-9v-battery/

[ripsdevala]

The optimal voltage is 12V.
I never tried it with 18V. The limitation will be the automatic adjustment range = offset of the opamp.
You can try it, but I would not recommend 2 x 9V blocks in series. These 9V blocks have very little capacity - they are made up of smaller cells in series.
10 x NiMH(12V) or NiZn ( 14 - 15V) or 3x LiIon is ideal.
These 9V blocks are insufficient ( capacity wise). They will work for only a short time:
http://www.astoriasoundworks.com/product/duracell-9v-battery/

I see, any idea how to charge 3 series LiLon with auto discharge and battery protection?

[F117]

I see, any idea how to charge 3 series LiLon with auto discharge and battery protection?

I am no battery expert, but there are many examples on the forum on how to do this. The easiest way is to charge them externally with a dedicated LiIon charger.
You can also add a cheap digital voltmeter to check the voltage before you go hunting. These things are very popular on ebay and other "low cost shopping" sites.

[Tim]

I see, any idea how to charge 3 series LiLon with auto discharge and battery protection?

Here's a couple of options ripdevala. I use the one off Ebay. Bat+Bat2Bat3 Neg(miss Bat4). P+andP- go to charger. I use a 1.5w 12v solar panel mounted on stem, or you can charge from any un-regulated 12v supply. No fancy expensive chargers needed.
4amp, so you can also hook P+/P- to circuit. (The reg in green tape was omitted once I changed 7660 for 1054).

[ripsdevala]

Let me try to find that module at local ol shop, or charge battery externaly for the last option.
Pikini is very picky with voltage i think, i will try 14v to make it last longer.
Btw i already try many coils from 310uh 1.3R, 340uh, 360uh, 430uh, more industance have a lower emi effect and low sens, lower industance more sensitive with stronger emi effwct.Cmiiw

[morganton]

Video of Pickini 4

I have uploaded a youtube video of my partially constructed Pickini 4 showing the start-up sequence and air detection of a U.S. quarter, dime, penny and nickel as well as a .304 gram flake of gold.

Depending on your hearing, you will probably need to turn your PC speakers volume up to hear the startup and detection tones. I apologize for the quality of the video (hard to hold the camera and operate the detector at the same time), but hopefully it will give you some idea of the detector's capabilities.

https://youtu.be/a0LL7zn0drU

I still need to put the coil in its housing and finish building the stem assembly, etc.

The coil is 21 cm diameter, 23 turns of 26 AWG enameled wire, 310 uH, 2.1 ohms. I used mylar for the shielding.

I want to thank F117 and the other contributors for a great project and the help I needed to get it running.

[Tim]

Good vid morganton. A bit of narrative would've been good- a bit hard to judge the distances. Bernards baby is a worthwhile project.

[morganton]

Good vid morganton. A bit of narrative would've been good- a bit hard to judge the distances. Bernards baby is a worthwhile project.

Yeah, I stumble through youtube videos so much that I just thought I would leave off. But here are the approximate depths:

Quarter about 20 cm.
Dime about 15 cm
Nickel about 18 cm
Penny about 16 cm
.304 gram gold about 3 - 5 cm

It will detect my pocket knife about 35 cm (forgot to show that in the video).

This is in my dining room with, I'm sure, lots of electrical interference around.

[F117]

Nice video, morganton
Now for a complete detector and a video from the beach !

Best regards,
- Bernard