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

[BC547]

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.

[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?

[BC547]

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]

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

[BC547]

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.

[Arionas]

BS170 connections on my original schematic

http://users.telenet.be/willaert/MD/pickini/pics/v4/pickiniV4_schematic.png

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

[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).

[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.

[BC547]

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.

[ripsdevala]

Don't press pin point switch when first start tuning, not long before 20sec you will hear small noise, indicate the md is ready to use, otherwise check your battery.

[morganton]

What momentary switch? The pinpoint switch ? This should not reset the controller.

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.

[BC547]

If I press the momentary switch,

What momentary switch? The pinpoint switch ? This should not reset the controller.

[morganton]

Power on -> welcome sound -> slow tick -> and do you hear a constant low tone after about 30 s ?

No, I hear just the welcome tones and then the slow tick. If I press the momentary switch, the process starts over with the welcome tone. Just curious, what is the frequency of the low tone?

[BC547]

Power on -> welcome sound -> slow tick -> and do you hear a constant low tone after about 30 s ?

[morganton]

According to this datasheet of the BS170 from Fairchild - the orientation on your board seems ok:
http://www.farnell.com/datasheets/2164079.pdf

Thanks for that. I was hoping that I had it oriented incorrectly so it would be an easy solution.

If the coil is not connected, would the voltage on pin 5 of LM318 be high, such as I am seeing?

Is the slow click after the opening tones normal?

Any suggestions about what to try first? I guess I can replace the BS170.