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

[useus]

You can try connecting a piezo buzzer directly to the headphone output. You may have to reduce the 1K series resistor.
Better would be to use an extra FET eg BS170 to drive a buzzer/speaker

can i use a felezjoo pi schematic for speaker?
Pin 11 direct to base of transistor

[BC547]

You can try connecting a piezo buzzer directly to the headphone output. You may have to reduce the 1K series resistor.
Better would be to use an extra FET eg BS170 to drive a buzzer/speaker

[useus]

I would like to use a classic little buzzer instead of a headphone, can I easily connect it to one of the two pins (+ gnd) of the headphone?

[useus]

Hi Bernard,,,,,Yes, those 3dss coils work brilliantly on your Pickini 4,,,I have tried it with both Copper enamelled wire and stranded wire,,,stranded wire working the best,,,I made 2 x 3dss test coils with single strand copper enamelled wire, one with 0.5mm and one with 0.7mm,,the 3dss with 0.7mm was more sensitive (by about 1" inch) than the 0.5mm wire,,,but both single strand coils, even though they were wound with the same geometry/configuration were 3"-4" less in depth than winding one with 16 strand 0.5mm (600v) wire,,,,,in fact, while I was testing all 3 of the coils the other day (on woodland paths near my home), I found a large women's gold ring that contained diamonds,,,it was at a depth of 12"-13",,,I made sure I covered the same area with all 3 coils and by doing that the 2 x enamelled wire coils had missed the ring, but when I went over the area a 3rd time with the 16 strand wire coil I got a loud target,,,I was surprised how loud it was at the depth I recovered it from,,I make all my P.I Monocoils with this method and wire and nothing else because I'm so pleased with them,,,,when I have time later, i'll clean the ring up a little more and post a photo of it before my partner claims the ring as hers!,,lol. It's a brilliant little detector and the 2nd one I made for my partner is as sensitive as the 1st so I'm really pleased. I think I'll be detecting a lot more of these country paths!,,The beach is too far anyway,,lol. Thanks. Marty

Could you tell me exactly the 0.5mm 16 strand wire you used?
I would like to create the attached coil, I printed it 1:1 but I have doubts whether all the thread will fit, can you confirm that it works? thanks

[useus]

The code won't fit into a PIC16F1823 - this only has 2K of program memory and around 3K is needed.
The PIC16F1824 has 4K of program memory.

I thought it was there, patience, I'll wait, thanks

[BC547]

The code won't fit into a PIC16F1823 - this only has 2K of program memory and around 3K is needed.
The PIC16F1824 has 4K of program memory.

[useus]

useus
The 4p7 cap can be 5pF or can be omitted - it reduces the opamp bandwidth
The 4k7 potmeter can be 10K - no problem

thanks for the information.

I have a problem compiling pickini 4.2 with mikroc pro 5.61, could you please compile it for pic16f1823? I have one to try while waiting for the 1824 to arrive, the 1823 is the same but has half the RAM and program memory

[BC547]

useus
The 4p7 cap can be 5pF or can be omitted - it reduces the opamp bandwidth
The 4k7 potmeter can be 10K - no problem

[useus]

@useus:
As you probably know, the Pickini detector is a temporal sampling PI, in other words, it measures the flyback pulse width iso the voltage.
The most critical peripheral used from the PIC16F1824 is its 32 MHz timer/counter that can be gated with the output of a voltage comparator. ( input = flyback signal )
The higher the counter clock frequency, the more accurate the pulse width measurement.
The DAC output and PWM outputs are also used as DC voltages for the comparator reference input and the opamp DC bias.
In retrospective: a 10 bit PWM output would have been better here than the 5 bit DAC output.
Another thing that could be implemented better is the power supply of the opamp: with a symmetrical power supply there is no need for AC coupling the flyback signal into the comparator / ADC input of the PIC.
This AC coupling has an average DC level that shifts the moment the pulses are not equally spaced anymore. So, accurate timing - interrupt triggered is essential here.
The same flaw was copied from the first Pickini V1 schematic into the Felezjoo.
A DC coupled signal would be more stable, independent of the pulse spacing.

So: timers, gated counters, PWM, ADC,... + all the other goodies on the ESP32 ( bluetooth, wifi, .. )?

You can find all info on the Pickini here:

http://www.willaert.world/MD/pickini_en/V4/intro.html

Looking forward to your implementation,
- Bernard

thanks for the answer but I'm not a programmer and I can't implement it on esp32, I thought there was an opportunity to be able to implement it easily.

while waiting for the pic to arrive, I'm assembling the components on the PCB, is it possible to use 5pf cap instead of 4.7pf cap?
I also miss the 4.7k potentiometer, can I use a 10k?


thanks

[BC547]

@useus:
As you probably know, the Pickini detector is a temporal sampling PI, in other words, it measures the flyback pulse width iso the voltage.
The most critical peripheral used from the PIC16F1824 is its 32 MHz timer/counter that can be gated with the output of a voltage comparator. ( input = flyback signal )
The higher the counter clock frequency, the more accurate the pulse width measurement.
The DAC output and PWM outputs are also used as DC voltages for the comparator reference input and the opamp DC bias.
In retrospective: a 10 bit PWM output would have been better here than the 5 bit DAC output.
Another thing that could be implemented better is the power supply of the opamp: with a symmetrical power supply there is no need for AC coupling the flyback signal into the comparator / ADC input of the PIC.
This AC coupling has an average DC level that shifts the moment the pulses are not equally spaced anymore. So, accurate timing - interrupt triggered is essential here.
The same flaw was copied from the first Pickini V1 schematic into the Felezjoo.
A DC coupled signal would be more stable, independent of the pulse spacing.

So: timers, gated counters, PWM, ADC,... + all the other goodies on the ESP32 ( bluetooth, wifi, .. )?

You can find all info on the Pickini here:

http://www.willaert.world/MD/pickini_en/V4/intro.html

Looking forward to your implementation,
- Bernard

[Pete61]

I was asking for pickini, not for other projects

I hear you, but it seems like you'd have to reverse engineer what pin of the PIC correlates to the ESP32 and then transpond the code functions.

I figured it might be easier to start an esp32 detector as an existing complete project.

[useus]

Its only Marcel that did the ESP32 MD that Ive been able to find via Google.
That was 6 yrs ago and I dont know if he resolved the issues he was having to get the project to work as he would have liked.


https://www.geotech1.com/forums/foru...etal-detector=

https://github.com/folny/ESP32_Metal_Detector

I was asking for pickini, not for other projects

[Pete61]

I would like to know if it was possible to convert this project for esp32, technically esp32 has all the features (and improved ones) of pic16f1824

Its only Marcel that did the ESP32 MD that Ive been able to find via Google.
That was 6 yrs ago and I dont know if he resolved the issues he was having to get the project to work as he would have liked.

https://www.geotech1.com/forums/forum/technology/tech-forum/15072-esp32-metal-detector?24589-ESP32-Metal-detector=

https://github.com/folny/ESP32_Metal_Detector

[useus]

I would like to know if it was possible to convert this project for esp32, technically esp32 has all the features (and improved ones) of pic16f1824

[Olly]

F117, this is one of the most elegant designs that I've seen in a long time. I realise that you designed this some time ago, but even so, I love that you have only included everything that is necessary and nothing that is not.

I'm going to build this as a Christmas project.

Many regards