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

[moodz]

Which version did you load .. ie post number?

[Gunghouk]

Post #248

2023-06-07 V1.4

[moodz]

Try this firmware .. note it is in DEVEL status but fixes some bugs from 1.4 and has the target modulated volume code.
However note that the manual volume control wont work ...

For full sensitivity there are some minor component changes .. but no changes to the 1.3 PCB.

[Gunghouk]

Thanks Moodz, board is 99.9% done and just waiting for your final deliberations on opamps etc.

[moodz]

This is the FINAL version of the MAGPI v3.
There are NO changes to the PCB layout. ( ie use the originally published PCB )
Some components were added. ( Originally not fitted to PCB )
Some components were removed. ( Originally fitted to PCB)
Some component values changed. ( Originally fitted but must be changed )

The original choice of opamps was the best ... ( others were tried ... they died ).
ie LM6171 for U2 and NE5534 for U3.

CHECK THE SCHEMATIC.

Here it is.

[moodz]

doh ... typo on the damping mosfet ... Here is the FINAL FINAL schematic.

[Gunghouk]

Hi Moodz is the change to D3 purely due to higher breakdown voltage or some other reason. I have a MUR460 in my box of bits with a 4A, 600v rating so presumably that would do?
Is R12 coil dependant and if so what is the selection criteria/formula?

Thanks

[moodz]

Hi Moodz is the change to D3 purely due to higher breakdown voltage or some other reason. I have a MUR460 in my box of bits with a 4A, 600v rating so presumably that would do?
Is R12 coil dependant and if so what is the selection criteria/formula?

Thanks

D3 can be almost any fast recovery diode rated for higher than 250 volts reverse and less than 1 volt forward voltage at 400 mA.
MUR160s are cheap and available ... MUR460 should work fine too.

R12 is set to "safe" value of 330 ohms .... the coil should be 300 microhenries +/- 10%.
R12 mops up the residual damping when the diode D2 stops conducting after the damping current stops flowing.

[moodz]

... one of the biggest issues with metal detectors is the physical weight. You have to carry it around.

Adding the LCD and rotary encoder just adds more to lug around. A 5 gram bluetooth interface is much cleaner.

Software does not weigh anything so I have reworked the Android app for the MAGPI. Coming soon ...

[moodz]

[Gunghouk]

Looking good. Can't wait to give it a try

Will the HC-05 run on 3.3v or need 5v?

[moodz]

Looking good. Can't wait to give it a try

Will the HC-05 run on 3.3v or need 5v?

I have never found a HC05 ( hundreds ) that wont run on 3.3 volts and in this case it obviously works.
However 5 volts is available from the TX regulator if required.

[moodz]

[IBGold]

Been watching in the background will get back into it when I get out of hospital hopefully the final operation is on the 23rd Cheers.

Regards, Ian.

[moodz]

Been watching in the background will get back into it when I get out of hospital hopefully the final operation is on the 23rd Cheers.

Regards, Ian.

Get better soon Ian.