Moodz' Awesome Gold Pulse Induction Version 3 - MAGPI V3 Project

[moodz]

WHOOPS ... one additional change I need to include.

We deleted R6 .... but you must add back in R12 ( see schematic in post #1 and PCB in post #2 )
I have use 470 ohms. ( Metal film 1% )



so the change instructions are now ..

1. REMOVE R6 ( DO NOT FIT )
2. CHANGE R7 to 100K
3. REMOVE D6
4. CHANGE R13 & R14 to 10K
5. CHANGE C5 & C4 to 1 uF ( FILM CAP )
6. REMOVE R1 ( DO NOT FIT )
7. REMOVE D8 ( DO NOT FIT )
8. CHANGE R20 to 10 MEG ( metal film 1/4 watt )
9. CHANGE C1 to 1uF ( FILM CAP )
10. CHANGE C3 to 0.22 uF ( FILM CAP )
11. ADD R12 470 ohms.

[moodz]

If you want the increased stability and sensitivity as shown in the video of post #338 these are the required hardware changes.

1. REMOVE R6 ( DO NOT FIT )
2. CHANGE R7 to 100K
3. REMOVE D6
4. CHANGE R13 & R14 to 10K
5. CHANGE C5 & C4 to 1 uF ( FILM CAP )
6. REMOVE R1 ( DO NOT FIT )
7. REMOVE D8 ( DO NOT FIT )
8. CHANGE R20 to 10 MEG ( metal film 1/4 watt )
9. CHANGE C1 to 1uF ( FILM CAP )
10. CHANGE C3 to 0.22 uF ( FILM CAP )

These changes will increase the preamp gain from 100 to 1000 ( from 40 db to 60 db gain ) and baseline stability is greatly improved.

Now I did say that you would not have to cut a track on the original PCB .... but you may or may not have to.

So if you make the changes above but the sensitivity is not what it should be ( as in the video of post #338 ) then I will advise the track to modify. Let me know if required.

I will also be changing U2 .... but waiting for parts to test ... the video demo in #338 uses the LM6171.

Should work with the 1.4 firmware but will be releasing 1.5 shortly when I get the U2 part.

[moodz]

I found that there are two versions of the PCF8574 IC. One is PCF8574A and the other is PCF8574T. If moodz wrote the code for the "A" version, your "T" may not work without changing the address in code.

See this

https://alselectro.wordpress.com/201...odule-pcf8574/

Good call.

[moodz]

Here is a 3F address firmware.

MAGPI008_2023_06_07_V1.4_RELEASE.X.production_LCD3F.zip

[moodz]

It is set for 0X27 in the code ... corresponding to 000 address ... so its the T version I think.

So you need an address of 3F instead of 27

[Altra]

I found that there are two versions of the PCF8574 IC. One is PCF8574A and the other is PCF8574T. If moodz wrote the code for the "A" version, your "T" may not work without changing the address in code.

See this

https://alselectro.wordpress.com/201...odule-pcf8574/

[Altra]

Every time I have problems with I2C it's always the device address. I can see three empty jumpers on the black pcb, marked A0,A1 A2. Maybe check Moodz's code for the device address and then short the correct jumper?

[Gunghouk]

Here's my display and I2C adapter.
The display works fine over I2C on an Arduino Nano project @ 5v.

[moodz]

If it works on everything then that'll do me.
I tried supplying the lcd with 5v but no joy. Just wondering if I've missed something that needs enabling in the software.

Should just work ...provided connections are good. Can you post photo of back of display ?

[Gunghouk]

If it works on everything then that'll do me.
I tried supplying the lcd with 5v but no joy. Just wondering if I've missed something that needs enabling in the software.

[moodz]

Thanks for the update. JLC pcbs are on the way here also

I've programmed a Pic but can't get the Lcd to work is there something needs enabling in the software? It's V1. 4 version. I've a 3.3v LCD2004A version on order so I'm hoping it may be that my current display is 5v only.

Here in the UK there's a shortage of diggible gold so another question is can it be modded for artifact hunting?
Thanks in anticipation.

Try jumping a wire over to the 5 volt TX supply .. instead of the 3.3 on the header.

Unfortunately I wont have iron reject ... that will be V4. ( so it will be dig everything ?? ).
I never really understood discrim detectors in artifact hunting .. aren't roman spear / arrow heads made of iron ?

[Gunghouk]

Thanks for the update. JLC pcbs are on the way here also

I've programmed a Pic but can't get the Lcd to work is there something needs enabling in the software? It's V1. 4 version. I've a 3.3v LCD2004A version on order so I'm hoping it may be that my current display is 5v only.

Here in the UK there's a shortage of diggible gold so another question is can it be modded for artifact hunting?
Thanks in anticipation.

[moodz]

I am waiting on a parts order but the good news is ...
Thanks to a breakthrough in preamp design ... the magpi can now hit larger deep targets and small sub microsecond tau targets much better.

The changes to the V3 circuit are minimal. Few firmware changes also.

Here is a video of the MAGPI detecting a sub microsecond tau target and also a larger target at 1 meter in the lab.

https://youtu.be/2F6O45bi3pA?si=dkC4dogkrjrqWbWO

[moodz]

I was a bit doubtful but I have increased the preamp gain from 100 to 1000 ( 40 db to 60 db ) and had to back off the sampling points.

The reason for this is to hit the 2CDCCD specification.
The 2CDCCD ( or 2 COIL DIAMETERS COKE CAN DETECTION ) test is a indication if your detector is actually working or maybe you should take up building props for science fiction movies.

Tested the MAGPI detector with a 40 cm ( 17 inch coil ) and it detects a coke can at 80 cm .. which is two coil diameters.

The GEB ground balance has been adjusted to move the detection "hole" to the far left so instead of creating a gap in detection range just the end of it has been clipped. Very small targets ( eg smaller that 0.1g ) have reduced sensitivity because of this.
The GEB is running all the time and if you rest the coil will balance out small targets BUT when you move the coil off the target .. will have to balance the ground again ( approx 5 seconds ). Its all done for you and theres no pumping of the coil etc.

Even with the large coil it easily detects 0.1 gram targets and does not respond to ferrites.
Noise has been reduced and there are actually less components now than in the original V3.

I will be out this weekend testing and update you then.

[Gunghouk]

Can't wait