New Bipolar Boost TX and Front End

[KingJL]

Menu/Display System

For those not familiar with the Digilent OLEDrgb (96x63) display module, it displays 12 characters per row and 8 rows. My thoughts on the display for normal operation and the menu system are as follows:

In normal operationthe display will be:

Bipolar PI

S1


S2


Sens


Where the special symbols will be illuminated depending on signal strength for S1 and S1. The Sens symbols will indicate the Sensitivity setting and can be adjusted with the encoder knob. Default sensitivity will be all illuminated.
To go from normal operation display to the menu system, press the encoder shaft button. When the main Menu is exited the display will return to the normal operation mode. The main menu will exit when "Exit" or "Probe" ("Search") is selected.
The "Select" or menu item is selected by pressing the encoder shaft button when the selection is high lighted.

The Main menus will be 8 items arranged in 2 columns:

Main Menu

GB PRT
Probe S1 (Probe/Search)
Maint S2
Filt Exit

In theMain menu in normal operation, the 2^nd entry text will be "Probe"; In probe mode operation the 2^nd entry text will be "Search".
The PRT, S1, and S2 sub-menus will be the display of the numerical value in usec and a "Select" item. The Filt selection sub-menu will be a numerical filter selection (that relates to speed of the response) for the mineralization compensation filter and a select item.i
The Maintenance menu will exit back to the Main menu when either "Exit" or "IB COIL" ("MONO COIL") is selected.
In all sub-menus where the numerical value is displayed with the "Select" entry, the numerical values can be changed by turning the encoder knob CW (+) or CCW (-).
The Maintenance sub-menu will be 4 items arranged in 1 column:

Maint

TX Off
Damp Tune
IB (Mono) Coil

Exit
In theMaint menu, the 2^nd entry text will be "TX OFF" if TX is currently on or "TX ON" if the TX is currently off. The 3^rd entry text will "IB Coil?" if current mode is mono coil or "Mono Coil" if current mode is IB coil.

These thoughts are extremely preliminary!

[Mdtoday]

I do not think cables pose any problems. .....
We may have a challenge with the Pmod OLEDrgb display.......
De-soldering components with multiple through holes without damaging the PCB can be problematic......

What are your thoughts on power source?
One other thought on the enclosure... Let's consider the option to use a switched probe. This requires space for a 3 position dpdt switch and another coil connector. Or the coil switch might be able to be accomplished with a solid state relay(s) and a small switch on the front of the enclosure with the relay control via the electronics. The later scenario would allow the probe operation even when using an IB main coil. The software could turn the IB receive path off during probe operation. I need to research for suitable solid state relay options.

I agree, SPI over a short screened cable at <5MHz will be Ok, I think the limiting factor is more likely the quality of the OLED module.

The draft design I posted earlier was designed to carry the PCBs in the vertical plane and accommodates a rear accessed bay for 2 x 18650 batteries. So all electronics mounted in the head.
Not shown on the drawing is the addition of the coil connector which is mounted rear facing at the base and on the side of the shaft clamp, a tear drop bump (I will post the updated models).
The internal coil cable runs up through the handle and is soldered directly to the PCB, it is unusual but effective as the coil connector is right next to the shaft.
There is another part to this enclosure design and that is the stand which will either be integral or a snap on, it is still to be decided.

There is a product called Chip Quick along with BGA flux for removing smd parts and connectors from boards with no damage, its not cheap but does last a long time.

On the power source, my preference is to keep things light as possible for gold prospecting therefore I generally use 2 high capacity 18650 batteries in my designs with 8 hrs run time.
The power pack is a great idea though and perhaps options for both should be included, I will work on this.

The switched probe is an excellent addition, a solid state switch would be my choice.

cheers

Mdtoday

[KingJL]

The switched probe is an excellent addition, a solid state switch would be my choice.

There are quite a few miniature DPDT relays with 3V or 5V coils (KEMET(EC2 series), OMRON(TX2 series), SAMSUNG, and quite a few Chinese manufactures). The KEMET and OMRON I know have contacts rated at 250VDC/225VAC. We would not want the ones with latching coils. After some thought and research, I believe the solid state switches would add in too much capacitance. It would be easy to add the AXI4 interface to the userinput module to control the DPDT relay circuitry. Having the switch controlled by the FPGA means that we can control the whole process (disable transmit, switch to mono operation if required, switch to probe, enable transmit). That way there are no spurious transients that can occur that are prone to occurring by just switching an active TX.

[Mdtoday]

For those not familiar with the Digilent OLEDrgb (96x63) display module, it displays 12 characters per row and 8 rows. My thoughts on the display for normal operation and the menu system are as follows:

These thoughts are extremely preliminary!

Looking good, menu layout and operational functions should do the job nicely and can be trimmed or extended as the project progresses.
It won't take long to figure out the most useful positions etc.

cheers

Mdtoday

[Mdtoday]

There are quite a few miniature DPDT relays with 3V or 5V coils (KEMET(EC2 series), OMRON(TX2 series), SAMSUNG, and quite a few Chinese manufactures). The KEMET and OMRON I know have contacts rated at 250VDC/225VAC. We would not want the ones with latching coils. After some thought and research, I believe the solid state switches would add in too much capacitance. It would be easy to add the AXI4 interface to the userinput module to control the DPDT relay circuitry. Having the switch controlled by the FPGA means that we can control the whole process (disable transmit, switch to mono operation if required, switch to probe, enable transmit). That way there are no spurious transients that can occur that are prone to occurring by just switching an active TX.

That is true, I would stay with OMRON or similar quality brand then as I have had recurring nightmare experiences with Chinese relay manufactures, they are not all bad but mechanical reliability on most leaves a lot to be desired.

I like the idea of controlling the switch-over process.

[KingJL]

I had envisioned a metal or metalized plastic 2"x2"x4" (inside dimensions) rectangular circuit enclosure ...

We need to wait until we actually mount the 10 pin connectors and marry the two boards and then measure what clearance we need. I suspect it will be about 2"x1 1/2"x4".

[Mdtoday]

We need to wait until we actually mount the 10 pin connectors and marry the two boards and then measure what clearance we need. I suspect it will be about 2"x1 1/2"x4".

I have been working on both enclosure designs using manufacturers 3D models and comparing with the real parts and they match quite well, this is the way I normally start enclosure designs. Also I set up parametric tables for the actual enclosure measurements and can change most things without having to redo the whole design, saves a lot of work.
I'll finish off this attached design then revert back to the rectangular one and finish that off when the OLED module arrives in 2 or 3 days.

The following pictures show the general idea with all of the mounting pillars and rear hatch.


I have 3D printed a half sized version to confirm it actually prints without problems and its Ok, so next stage is to correctly position the PCB mounting pillars and add some ribs, then do a full sized test print.

In the end I will have 2 versions for you to take a look at and decide on changes etc, I'll then either send STL files if you have a 3D printer or print a couple off and send if you would like them.

I will post progress on the rectangular version soon

Cheers

Mdtoday

[KingJL]

I'll finish off this attached design then revert back to the rectangular one and finish that off when the OLED module arrives in 2 or 3 days.

I think you may have miss-understood my "rectangular enclosure" vision. The "rectangular enclosure" than I was envisioning, was a sub-enclosure (metal or metalized plastic) much like the Vallons packaging of it's 2 main electronics boards. This was simply to provide more shielding to the sensitive areas of the electronics and to facilitate more abstraction for the support modules (power supplies (in my case 3 small boost regulators for 5V, 20V, and 3,3V) audio support circuitry, and coil/probe switch w/support circuitry) and how they are positioned. Sorry for the confusion. I like the designs that I have seen for the overall enclosure.

Also an update: I just changed the OLEDrgb support ip so that the SPI clock is upped to 6.25 MHz. I felt that this was justified by the fact that a majority of processing time will be spent in updating the display since there is a new received data set every 4 msec. This puts the SPI clock at the upper limit for the OLEDrgb module per the specification sheets. It has all tested out fine.

[Mdtoday]

I think you may have miss-understood my "rectangular enclosure" vision. The "rectangular enclosure" than I was envisioning, was a sub-enclosure (metal or metalized plastic) much like the Vallons packaging of it's 2 main electronics boards. This was simply to provide more shielding to the sensitive areas of the electronics and to facilitate more abstraction for the support modules (power supplies (in my case 3 small boost regulators for 5V, 20V, and 3,3V) audio support circuitry, and coil/probe switch w/support circuitry) and how they are positioned. Sorry for the confusion. I like the designs that I have seen for the overall enclosure.

Not a problem JL, I should have realised, I have a Vallon too, it just didn't click in my brain.

There will be plenty of room in the housing still, I can just enlarge by the required amount if needed.
I spray the inside of my 3d prints with nickle screening which does the trick or a ready made metal enclosure as you say.

Here is a view of boards mounted horizontal to give an idea of available space and where it will require adjustment to accommodate the shielded enclosure.

[Mdtoday]

Also an update: I just changed the OLEDrgb support ip so that the SPI clock is upped to 6.25 MHz. I felt that this was justified by the fact that a majority of processing time will be spent in updating the display since there is a new received data set every 4 msec. This puts the SPI clock at the upper limit for the OLEDrgb module per the specification sheets. It has all tested out fine.

That is great news

[KingJL]

Probe/Search coil switch relay

... I would stay with OMRON or similar quality brand then as I have had recurring nightmare experiences with Chinese relay manufactures, they are not all bad but mechanical reliability on most leaves a lot to be desired...

I have settled on the KEMET EC2-3NU. It is stocked by LCSC whereas the OMRON 3V version was not (and the OMRON cantact voltage rating was only 125V). The following circuit is the drive and connection configuration for the DPDT relay. It should provide adequate protection of the FPGA from transients in case of a relay malfunction. I have used this coil connection configuration in the Vallon with a DPDT manual 3 position switch.

[Mdtoday]

I have settled on the KEMET EC2-3NU. It is stocked by LCSC whereas the OMRON 3V version was not (and the OMRON cantact voltage rating was only 125V). The following circuit is the drive and connection configuration for the DPDT relay. It should provide adequate protection of the FPGA from transients in case of a relay malfunction. I have used this coil connection configuration in the Vallon with a DPDT manual 3 position switch.

Looks good JL, nice neat little circuit, thanks for sharing.
I'm currently working on a version of the sub-enclosure and will try post progress later today.

[KingJL]

Userinput module modified to support probe switch

I just modified the userinput module so that we can control the probe switch. Added the AXI4 bus that is needed to communicate from the embedded processor to the userinput module; removed the GB switch input as we will be using the menu system to initiate GB; added an output port to control the probe switch.

An updated project archive and block design will be posted later in the week. I have initiated a "Change Log" that will be posted with the project archive that will summarize changes that occurred in each archive version going forward (it will also be included in the archive).

The plan is to start programming the system now that all of the interfaces have been proven.

[Mdtoday]

Getting to the pointy end now, great work

[Mdtoday]

JL, is this the sort of sub-enclosure you were thinking of?



3D printing/nickel sprayed on inside for shielding

It is designed with small flanges which will slide into ribs on side wall of main enclosure.
PCBs held in place with spacers and screws through bottom of sub-enclosure then into small pillars on lid.
Not sure if you wanted A7 inside enclosure, this can be adjusted easily.

Bits and pieces like supports for power supply boards can be added if required.

cheers

Mdtoday