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

[F117]

The coil resistance should not be 0 ohms, rather 0.5 ohms or more. This is just a check if the coil is not shorted = 0 ohm.
But then you would get the 'coil error sound' = no flyback pulses detected.

To put evertything on a timeline - please correct me if this is wrong:

- you have built this PCB, connected a coil and everything worked fine ? Normal detection sensitivity ?
- some time later, the sensitivity has decreased ?

Can you check on pin 3 of the PIC16F1824 if the sensitivity setting is changing between 0 and 5V when you turn the sensitivity potmeter ?
Also check the capacitor that is in parallel with the 1M feedback resistor of the opamp LM318. It should not be more than 4.7 pF.
You can even remove this capacitor.

Also check all DC voltages with a multimeter on each pin of the microcontroller and the opamp:
The reference voltages are here:
http://www.willaert.world/MD/pickini...ectronics.html

[Reedick]

Hi friend i try lm709 it works but the same problem sensivity decreassed

[kt315]

Hi friend i try lm709 it works but the same problem sensivity decreassed

you use obsolete and slowlest opamp in the world. it has 0.25V/us slew rate, just, compare with LF357 having 50V/us.

[sbalio1]

Ok.kt315

[Alpi]

Hi Bernhard
Can I buy a microchip from you the 16F1824 with program pickini v4 for contact [email protected]

[F117]

Alpi : you've got mail.

You may have noticed that I removed the "Shop" page from my website for 2 reasons:
1 / I am running out of 16F1824 and they are phasing out
2a / I used to send every kit/controller via normal post mail. Not via DHL or other courier. In some countries, the normal mail proved to be "not so trustworthy" to put it mildly and some kits got lost in transit...
2b / I don' have enough spare time to assemble these kits and put them into the mail anymore...

You can still obtain the 16F1824 online.
Then try to find somebody who has a PicKit3 progrmammer ( or buy one ) and download the hex file from my website: http://www.willaert.world/MD/software/v4/Pickini4.1.hex

[MDfanatic]

F117 would it be better if the Pickini was powered with 3 x 18650 or by 4 x 18650?

[F117]

I always used a batterij pack of 3 x18650 in series.
This gives you in theory 3 x 3.7 V = 11.1V.

An alternative would be tobput thé 3 x 18650 in parallel and connect a cheap upconverter that can be adjudted tot 5V.
And a 5V USB C charger.

[F117]

Better without auto correction:
An alternative would be to place the 3 x 18650 in parallel and connect a cheap upconverter that can be adjusted to 12V.
And a 5V USB C charger.
Something like this: adjust the output voltage to whatever you want
https://www.amazon.com.be/-/nl/Step-up-voedingsadapter-Arduino-Raspberry-projecten/dp/B06ZYYC99S/ref=sr_1_18?crid=2X70L277N7P5J

The main argument to not to use an upconverter would be switching noise.

[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

[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

[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/foru...etal-detector=
https://github.com/folny/ESP32_Metal_Detector

[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 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.

[F117]

@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