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

[BC547]

Hi reptooyep,
Your setup looks very interesting!
Is that an inductive charger ?
Can you give some more info on these other parts?

[reptooyep]

[reptooyep]

Hi Bernard,
Your advices are great. I found an old relay i 've disassembled it to keep only the contacts and i've glued a small hard disc magnet piece on it.
On the case, i've glued a piece of electrical plastic trunk with another hard disc magnet and it works just fine.
I've added a QI charging unit and now, the last thing to do is the rod..
Thanks for help, i realy appreciate.

[BC547]

I had the same experience with a light reed switch, intended to turn the detector on and off with an external magnet.
The inrush current from the batteries is too high.
The switch contacts are instantly welded together and the detector will never turn off again - after removing the magnet.

I had better results with a small 5V relay and a small but powerful neodymium magnet. When held close ( thickness of the housing) to the relay contacts, they make contact.
However, a more powerful reed relay should do this job better.

Your solution with the switching transistor looks OK to me, but I would still add a resistor from base to ground in the case of this NPN transistor. Also, I would put the load ( the detector ) at the collector side. Typically a PNP transistor is used with emitter at the battery plus, a pull up resistor from base to emitter and a pull down resistor in series with the magnetic switch to ground. When the switch is open, the base is pulled up to the emitter voltage and the transistor shuts down. The load would then be between collector and ground.

No idea if the remaining current, when the transistor is open, will drain the battery...

I am sure that people on this forum have better solutions than this. My best guess here is a reed relay that can handle the large rush-in current...

As you can see from previous pictures of my underwater version, I ended up placing the potmeter/switch combination inside the housing. This implies that you have to open it up and switch it on + set the sensitivity before each use.

Success !
- Bernard

[reptooyep]

I took off the damping 1K resistor and replaced them by a 1/2W TH 390ohms one and the sensitivity is just perfect.
I also replaced the pot. by two resistors (55k - 33k) so, no problem with that.
I put a magnetic switch inside the case and when i turn it on, it does not want to turn off without the magnet. The switch is not made to drain 4V/55mA (measured in working order).
I want to make a switching circuit with a transistor but i don't know how to choose it, exept with the current value. Could a silicon NPN do the job ?

[BC547]

The damping resistor = 1K||1K = 470 ohm should be 2x 1/4 W in parallel or 470 ohm 1/2 W.

Sensitivity: does the sensitivity input from the potmeter work? 0V = minimum sensitivity - 5V = maximum senitivity ( in reality to be used on deserted beaches only ). A realistic value is around 1 - 3 V to test around the house.
Do NOT modify the resistive 1/2 divider!
Check the sensitivity input first. If this is for an underwater detector, you can set it to fixed value of around 2 V ( 3k3 + 2k2 between 5V and Gnd e.g. ). This way you don't have to make a hole for the potmeter in your housing and seal the potmeter,... Unless of course you know how to do this fool-proof ( or water-proof in this case ).

[reptooyep]

Hi,
I just come back to the project after few month (my daughter was born four month ago).
I made the through hole version with the latest firmware. It works pretty fine with my 3dss coil.
The board is too big to fit my waterproof pressurised enclosure so, i planned to make my own SMD version.
The problem is that i get a VERY bad sensitivity with SMD and i don't know why.
I've noticed that the 470ohms resistor next to the two diodes burn with 1/8 W SMD resistors, you need to put 1/4 TH resistor.
Where can i increase the sensitivity ? I tryed modifying the resistor bridge before the PIC input without success.
Thanks for help

[nick holas]

hi bernte
hi F117
hi all
sorry for my long time answer (saddly lot of things change in my life, perhaps for better life?)
i haven t finished my smd pikini (lm318 still awaiting,smd capacitor too!!!!)
bernard your underwater pikini is fantastic!!!! maybe one day i ll make one or adapt smd pikini for underwater summer beach hunting
i ve finished an other PI MD witch look simple and promising but it don t work and don t have time and mind now to make it work so i m still awaiting too!!!!
have nice day

[bernte_one]

ah ok thanks for showing

yesterday i try my pickini v4, i have seen that the last Firmware was already installed
work very good with high / low led indicator

if i install a vibro Motor into the stem grip it woul be a good silent and non visible Option for very secret threasure hunting

[BC547]

Here are some pictures of my Pickini V4 dive detector.
The housing is this one: Basetech 1310189


There is only one hole - for the coil cable.
You have to open the box to access the on/off / sensitivity potmeter and the cinch battery charger connector.
The stem is also shortened to a little more than 1m. Coil is 20 cm.
Pin7 of the microcontroller is connected to the breadboard glued in the cover, with 1 transistor that switches on a bright red flashlight pointing to the coil + a hi-bright red LED inside the transparent housing.
Next to the red flashlight, there is a white LED flashlight that is continuously on.
I will still add a loud buzzer for extra detection indication. All driven by the same BC549 transistor connected to pin 7.

Some pictures:

[bernte_one]

i read post 291- what should i say it´s exactly that function i Need (low/high state for led or vibro), it totally missed this upgrade

thanks Bernard for your work excellent

[bernte_one]

Thanks Bernard,

i think i will try it with a bc547 as Transistor Switch piezo buzzer itself is loud enough for land but you are right for underwater i can also try a Transistor to get more power from buzzer

regards Bernd

[BC547]

Bernt,
you can connect a LED directly to pin 7 of the controller. This was added as described in post #291.
This is a simple on/off detection indicator. You can attach an extra transistor here to drive more powerful LEDs - or a powerful buzzer ( to be heard underwater, even without headphones . When you attach the buzzer to the housing, the noise can be heard underwater).
A single hi-bright LED can be connected directly to the pin via a 470E resistor.

- Bernard

[bernte_one]

Hello Nick,

did you get your smd Layout working?

i did some test with underwater coil made of cat 6 Network cable, Performance was very good
with a 20cm coil square shape i could detectect a 1L can at 70cm indoor
was not able to set to full sence in the house so i think outdoor it will give 90-80cm

but i still have Trouble with led Output instead of piezo buzzer

simple connect the led to pic Output does not work properly, yes i know i have to to connect a resistor in line for led protection

is there any way to create an alternative Driver that converts the Output Signal from pic Controller into smooth led behaviour (from off to full led light in conversion to pic output)
if not possible it would be also ok if led is off or on

you can test what i mean if you connect a led to Audio out from pic, but i think generated Signal is not best for led

[morganton]

Nice video . Thanks for sharing it !
Even when no treasures are found, at least you get some exercise and fresh air.
These are also the typical finds here on the beach. Pickini v4 finds our iron euro-cent coins very attractive...
Well, you dug the trash and found some cash, what more can you expect in the park ?

Nice move with the pinpoint pushbutton an a very professional looking build

Best regards,
- Bernard

Thanks Bernard. You put together a great project!