User Port Extender / SD Card Reader Interface

[KenLowe]

My 1MHz level shifter board requires a 5V supply to power the level shifter and RPi Zero. The usual source is either from the Tube port or the User port. However, if these ports are already in use, then an alternative source needs to be found.

If the tube port is in use, then I'm pretty sure in most cases there will be a PiTubeDirect hanging off it. As such, I've developed a tube level shifter that enables power pass through whilst connecting a PiTubeDirect to the port. However, I'm aware that some people have original CoPros, or are using the Matchbox CoPro, or a different level shifter that doesn't have any power pass through option. If this is you, and your User port is also in use for other purposes, then this alternative might just be what you need...

I've designed a small User port extender that has power pass through and it also has the necessary pins to directly connect up a cheap Micro SD card reader if you want to use the User port for a SD card based filing system. The User port extender should fit under the keyboard of both the Beeb and Master computers. Note that you should not try connecting something to the User port extender pins if you are using SD card reader function. You can, of course, use the power pass through when using either the User port extender pins or the SD card reader function.

I thought I'd gauge level of interest (if any!) before deciding if I should place an order.

User Port Extender / SD Card Reader Interface

>
Edit: And with the SD Card Reader plugged in:

With SD Card Reader Board Plugged In

[dudleysoft71]

Hi Ken,

This sounds like it would be an ideal solution, Ive been asked about adding mouse support for my frontier port, so I'm going to replace my mmc drive with a gotek (and replace my 8271 disk controller with a 1770), which means swapping power for the 1mhz shifter to the user port, which means I can't use a mouse.

I'm now stuck in a position where I can choose between any two of mouse/floppy/scsi. So being able to take power from the user port and still run a mouse would be useful for me.

[Wheel_nut]

Hi Ken,

The standard 30p SD Card reader comes with a right angle Header on the Component side which would have to be removed and replaced with a straight Header on the back.

It would appeal to more users if the two connectoes could be made to mate directly without needing soldering skills. Perhaps the easiest way would be to mount the Female connector on the other side of your Board and simply straighten the Pins of the SD Card reader ... if space was not an issue.

Robin

[KenLowe]

The floppy port doesn't have a 5v feed so adding a Gotek shouldn't make any difference to how you power the 1MHz level shifter. Unless of course you're currently using the PSU auxiliary port to power the 1MHz level shifter, and you're now wanting to use that to power the Gotek? If this is the case, I assume your Tube port is also in use and also unable to provide power to the 1MHz level shifter? In which case, then yes this should solve your power problem, whilst still being able to use the User port for other purposes.

Sorry if you've mentioned this to me previously. I've got a faint recollection that someone was planning to use the PSU auxiliary port to power the 1MHz level shifter. I guessing it might be you.

Even though I got no initial response to this post I still decided to order up a small batch of PCBs and associated IDC connectors so I could test this out. I expect these to be delivered in the next couple of weeks. Let me know if you're interested in purchasing one and I can set one aside when they arrive.

Best regards
Ken.

[KenLowe]

Hi Ken,

The standard 30p SD Card reader comes with a right angle Header on the Component side which would have to be removed and replaced with a straight Header on the back.

It would appeal to more users if the two connectors could be made to mate directly without needing soldering skills. Perhaps the easiest way would be to mount the Female connector on the other side of your Board and simply straighten the Pins of the SD Card reader ... if space was not an issue.

Robin

Yes, you're absolutely correct about header orientation. My intention would be to offer these SD card readers with the right angle header replaced with a straight header.

Edit: Perhaps it would have been more sensible if I had reversed the order of the 6 pin header on my board so anyone could have straightened out the pins on the SD card reader as you suggested, and plugged that directly into my board. The reason for the pin order being the way it is, was to have the sd card socket and other components visible, but in hindsight that probably isn't all that important. Perhaps a consideration if I make a rev 2 board.

[Wheel_nut]

Edit: Perhaps it would have been more sensible if I had reversed the order of the 6 pin header on my board so anyone could have straightened out the pins on the SD card reader as you suggested, and plugged that directly into my board. The reason for the pin order being the way it is, was to have the sd card socket and other components visible, but in hindsight that probably isn't all that important. Perhaps a consideration if I make a rev 2 board.

I think that having the SD Card Reader board face to face with your interface Board would make it less susceptible to damage in the Connector Well as the back of the SD Card Readwe is flat and free of components. I realise that it would need re-wiring on your Board to facilitate this. As you say, perhaps on a Rev 2 Board

[dudleysoft71]

The floppy port doesn't have a 5v feed so adding a Gotek shouldn't make any difference to how you power the 1MHz level shifter. Unless of course you're currently using the PSU auxiliary port to power the 1MHz level shifter, and you're now wanting to use that to power the Gotek? If this is the case, I assume your Tube port is also in use and also unable to provide power to the 1MHz level shifter? In which case, then yes this should solve your power problem, whilst still being able to use the User port for other purposes.

Sorry if you've mentioned this to me previously. I've got a faint recollection that someone was planning to use the PSU auxiliary port to power the 1MHz level shifter. I guessing it might be you.

Even though I got no initial response to this post I still decided to order up a small batch of PCBs and associated IDC connectors so I could test this out. I expect these to be delivered in the next couple of weeks. Let me know if you're interested in purchasing one and I can set one aside when they arrive.

Best regards
Ken.

Yes that was me, I've pretty much maxed out the ports on the underside, to run Frontier I need both the Tube and the 1Mhz bus for BeebSCSI since the main executable is 1.6Mbytes. I am using the aux power socket to power the 1Mhz shifter, I can swap that to the user port when I get the gotek, unless I want to use a mouse, while I can swap out the floppy for testing purposes it's not an ideal permanent solution.

And yes I'd be interested in a board once you've built one thanks.

[rharper]

I'd be interested in a board.
Ray

[KenLowe]

Boards arrived today, and the various headers arrived earlier in the week. That's allowed me to soldered a couple up for testing, and they're all working as expected.

If using the board to directly mount a SDCard reader (via the 6 pin header), then as wheel_nut has pointed out, it is necessary to remove the 90Deg 6 pin connector from the SDCard reader and replace it with a straight through 6 pin connector that needs to be soldered on the other side of the board.

You can obviously still use the User port extension header pins to connect any User port device (including a SDCard reader) to the beeb. You just can't connect a direct mount SDCard reader to the 6 pin header and something to the extension header pins at the same time.

Note that there is a small jumper on the board that links CB1 and PB1 together. This is necessary for the direct mount SDCard reader to work correctly. It should be removed if you're just wanting to to use the board in direct pin for pin User port pass through mode.

I need to get slightly longer jumper wires so I can connect between the user port extender and the 1MHz level shifter board without the need to use extension wires (as I've done in the photo). I've got some 30cm wires on order that should do the trick.

Only slight niggle is that the securing lugs on the beeb user port connector clash slightly with the power wires. It's not a major issue though.

1MHz level shifter picking power up from User port. User port is still available for any other purpose.

User port with direct mount SDCard reader plugged in

External SDCard reader plugged into the User port extension pins, whilst 1MHz level shifter is picking power up from User port.

External SDCard reader plugged into the User port extension pins, whilst 1MHz level shifter is picking power up from User port.

This one will only fit under the beeb. The header extension pins face the same direction as the pins in the main beeb connector.

[dudleysoft71]

Hi Ken,

Just to say I received the board this morning, I've plugged it in and connected the Pi1Mhz Level Shifter to it and it's powering fine, I've tied it with my MMC reader and it works fine with that, and I've got a Smallymouse on order, once that arrives I'll be able to test working with the mouse.

[1024MAK]

I've designed a small User port extender that has power pass through and it also has the necessary pins to directly connect up a cheap Micro SD card reader if you want to use the User port for a SD card based filing system.

Hi Ken

I would like two boards please.

I’ll send a PM in a moment...

Mark

[Wheel_nut]

Hi Ken,

The standard 30p SD Card reader comes with a right angle Header on the Component side which would have to be removed and replaced with a straight Header on the back.

It would appeal to more users if the two connectors could be made to mate directly without needing soldering skills. Perhaps the easiest way would be to mount the Female connector on the other side of your Board and simply straighten the Pins of the SD Card reader ... if space was not an issue.

Robin

Yes, you're absolutely correct about header orientation. My intention would be to offer these SD card readers with the right angle header replaced with a straight header.

Edit: Perhaps it would have been more sensible if I had reversed the order of the 6 pin header on my board so anyone could have straightened out the pins on the SD card reader as you suggested, and plugged that directly into my board. The reason for the pin order being the way it is, was to have the sd card socket and other components visible, but in hindsight that probably isn't all that important. Perhaps a consideration if I make a rev 2 board.

Ken, If you used a 6way x 1Row Right Angle Header like the one below for the Arduino connector, would it mate correctly without having to re-design the Board?

[KenLowe]

Hi Ken,

The standard 30p SD Card reader comes with a right angle Header on the Component side which would have to be removed and replaced with a straight Header on the back.

It would appeal to more users if the two connectors could be made to mate directly without needing soldering skills. Perhaps the easiest way would be to mount the Female connector on the other side of your Board and simply straighten the Pins of the SD Card reader ... if space was not an issue.

Robin

Yes, you're absolutely correct about header orientation. My intention would be to offer these SD card readers with the right angle header replaced with a straight header.

Edit: Perhaps it would have been more sensible if I had reversed the order of the 6 pin header on my board so anyone could have straightened out the pins on the SD card reader as you suggested, and plugged that directly into my board. The reason for the pin order being the way it is, was to have the sd card socket and other components visible, but in hindsight that probably isn't all that important. Perhaps a consideration if I make a rev 2 board.

Ken, If you used a 6way x 1Row Right Angle Header like the one below for the Arduino connector, would it mate correctly without having to re-design the Board?
6Pin Right Angle.jpg

The pinout would work fine, but I foresee a couple of problems. Firstly the right angle header would clash with the two existing right angle headers on the board. You could ditch these two headers, but purpose of this board was to provide power to the 1MHz level shifter via one of the headers. And the second header is needed to be shorted if using the MicroSD adaptor board. The second issue is that the MicroSD card adaptor is marginally too wide, and would clash with the User port header and the User port extension header, unless you can find a way to lift everything clear.

The main issue I've got with the current design is that the single row of 6 pins that hold the MicroSD adaptor board to the User port board are not sufficiently strong enough to hold the board tightly in position. Whilst it doesn't seem to affect the electrical contacts, the board ends up drooping at the SD card end. I was thinking of making a slightly different User port board that is slightly wider, and would allow the SD card end of the MicroSD adaptor board to be secured to the User port board; holding everything in place. At the same time, I would reverse the order of the 6 header pins. My only challenge here is that the mounting holes on the MicroSD adaptor board are very small, and I'm not sure what screws / spacers I'd use to hold the two boards in place.

[Wheel_nut]

The pinout would work fine, but I foresee a couple of problems. Firstly the right angle header would clash with the two existing right angle headers on the board. You could ditch these two headers, but purpose of this board was to provide power to the 1MHz level shifter via one of the headers. And the second header is needed to be shorted if using the MicroSD adaptor board. The second issue is that the MicroSD card adaptor is marginally too wide, and would clash with the User port header and the User port extension header, unless you can find a way to lift everything clear.

Yes, I have been looking at the dimensions again and agree that the board needs to be 25mm between the nearest pins of the two headers so probably needs a re-layout to do what I am trying to adapt your design to do for me. Idleness being what it is, I am playing with KiCAD to see what I can fit into a single board in the available space.

The main issue I've got with the current design is that the single row of 6 pins that hold the MicroSD adaptor board to the User port board are not sufficiently strong enough to hold the board tightly in position. Whilst it doesn't seem to affect the electrical contacts, the board ends up drooping at the SD card end. I was thinking of making a slightly different User port board that is slightly wider, and would allow the SD card end of the MicroSD adaptor board to be secured to the User port board; holding everything in place. At the same time, I would reverse the order of the 6 header pins. My only challenge here is that the mounting holes on the MicroSD adaptor board are very small, and I'm not sure what screws / spacers I'd use to hold the two boards in place.

However, unlike Steve Picton's board, you mount the PCB Under the Headers and this gives at least another 8mm headroom so the two boards could be separated by 8 - 10mm in a redesign to allow nylon standoffs like the examples I have linked below to be used.
https://www.aliexpress.com/item/3270276 ... hweb201603_
(Other products are available...)

[KenLowe]

Those stand-offs look ideal. I'm only proposing to use a single standoff. I don't want the board to start clashing with the IDC lugs on the beeb connector. This is roughly what it would look like. Hopefully I've got the mounting hole in the right position! I'm going to be placing an order shortly for some other boards, so I'll get a small batch of these made up at the same time and see how they come out.

Edit: I've deleted the renders from this post, and provided updated renders further below.

[Wheel_nut]

Those stand-offs look ideal. I'm only proposing to use a single standoff. I don't want the board to start clashing with the IDC lugs on the beeb connector. This is roughly what it would look like. Hopefully I've got the mounting hole in the right position! I'm going to be placing an order shortly for some other boards, so I'll get a small batch of these made up at the same time and see how they come out.

Hi Ken, In my playing with KiCAD, I think I may have a way of avoiding the need for the Jumper to connect the CS Pin to Ground.

I wired CS to Pin 5 of the User Port but wired 7.9.11.13.15.17.& 19 to the GND Pin of the SD Card adapter. I think this obviates the need for the Jumper ... or have I missed something?
EDIT: Scratch that!!! It must be past my bedtime .... The jumper is to connect Pins 2(CB1) and 8(PB1) !!!

Robin

p.s. I am trying to lay out a board with a 20 pin User Port Connector on one side and a 26 Pin (Printer Port) on the other so that it can be used with either U/MMFS or P/MMFS. I am stuck at the Footprint assignation step and have chucked it for tonight.

[KenLowe]

I think I may have a way of avoiding the need for the Jumper to connect the CS Pin to Ground.

I wired CS to Pin 5 of the User Port but wired 7.9.11.13.15.17.& 19 to the GND Pin of the SD Card adapter. I think this obviates the need for the Jumper ... or have I missed something?

Hi Robin. The jumper (JP1) connects user port CB1 and PB1 together, and these both connect to SCK on the MicroSD Adaptor. Here's a copy of the Kicad schematic:

User Port Adaptor

[KenLowe]

Right, I've tidied up the board a bit, and hopefully have the mounting hole in the right position now! I've also made a slightly nicer 3D model for the MicroSD card Adaptor. I was exporting as STEP, and it didn't take across the pads or the silkscreen. The solution was to export as VRML (.wrl) instead.

With MicroSD Card Adapter board unplugged

With MicroSD Card Adapter board unplugged

With MicroSD Card Adapter board inserted

With MicroSD Card Adapter board inserted

[Wheel_nut]

Hi Ken,

That looks perfect and the only potential, though unlikeky problem is the protrusion of the Nylon Pillar on the bottom of your board touching the slope of the Beeb Case as your Board lies flat to the case. If it does, it can be easily remedied by so;dering the Header at a slight angle to compensate as there is plenty of headroom in the connector well.

Your extended board profile is also perfect for what I am wanting to do. I want to replace the downstream 20Pin Header with a 26Pin connector to mate with the Printer Port and wire it to Dave (Hoglet)'s P/MMFS design:

CS <== Pin 4
SCK <== Pin 5
MOSI <== Pin 3
MISO ==> Pin 25
VCC === Pin 26
GND === Pin 6

This would create a multi-purpose adapter for those of us who use both the U/MMFS and P/MMFS variants (though not simultaneously of course!)

I fell at the Footprint allocation stage of KiCAD last night! If you are able and willing to do this, I would be very happy to fundor buy the initial batch or build them up from the raw Board.

Robin

[KenLowe]

Hi Ken,

That looks perfect and the only potential, though unlikely problem is the protrusion of the Nylon Pillar on the bottom of your board touching the slope of the Beeb Case as your Board lies flat to the case. If it does, it can be easily remedied by soldering the Header at a slight angle to compensate as there is plenty of headroom in the connector well.

Your extended board profile is also perfect for what I am wanting to do. I want to replace the downstream 20Pin Header with a 26Pin connector to mate with the Printer Port and wire it to Dave (Hoglet)'s P/MMFS design:

CS <== Pin 4
SCK <== Pin 5
MOSI <== Pin 3
MISO ==> Pin 25
VCC === Pin 26
GND === Pin 6

This would create a multi-purpose adapter for those of us who use both the U/MMFS and P/MMFS variants (though not simultaneously of course!)

I fell at the Footprint allocation stage of KiCAD last night! If you are able and willing to do this, I would be very happy to fund or buy the initial batch or build them up from the raw Board.

Robin

I'm not sure I fully understand what you're trying to do here. Are you thinking about making a 'universal' board with printer port connection on one side and user port connection on the other, with the sole purpose of using either the printer port or the user port to a MicroSD Card Adapter?

If that's what you're looking for, I don't think it would work with the standoff I've just added. That part of the board would clash with the case / connector lugs. If you were to exclude the standoff then it might just about work.

Also, I presume of you're using the printer port then you would need an external power supply to power the MicroSD Card Adapter? Let me knock something up in KiCAD and see if that's what you're thinking of...

Edit: Something like this? This wouldn't fit under the case of a Master. If making it purely for the beeb, I could widen then board a little bit, and that would probably give us enough space to add the standoffs back in.

[Wheel_nut]

I'm not sure I fully understand what you're trying to do here. Are you thinking about making a 'universal' board with printer port connection on one side and user port connection on the other, with the sole purpose of using either the printer port or the user port to a MicroSD Card Adapter?

Yes, that's exactly what I need. There seem to be many of us who are now using Dave's P/MMFS design so as to free up the User Port for other devices such as an EPROM Programmer. There is currently no off-the-shelf adapter so most of us have resorted to wiring an Arduino MicroSD Card to a short cable. This seems like the obvious solution!

If that's what you're looking for, I don't think it would work with the standoff I've just added. That part of the board would clash with the case / connector lugs. If you were to exclude the standoff then it might just about work.

My plan was to widen the Adapter sufficient to clear the Printer Port Clips. I don't have a Master so can't check but a possible solution for Master users wanting to use the Printer Port would be to not fit the User Port Header. I like your solution of the standoff to steady the Board. I found those and also Double Sided Sticky Pad versions when looking for ways to secure my RPi1 on your extended Tube Level Shifter.

Also, I presume of you're using the printer port then you would need an external power supply to power the MicroSD Card Adapter? Let me knock something up in KiCAD and see if that's what you're thinking of...

No, Dave added a couple of "adds" to the Mainboard to bring Vcc out on previously unused Pin 26 of the Printer Port so the adapter would not need external power. However, I would keep the Vcc and Gnd header on the adapter to enable it to power your 1MHz Bus Level Changer Board. Note also the PA7 Input signal added to previously unused Pin 25.

Edit: Something like this? This wouldn't fit under the case of a Master. If making it purely for the beeb, I could widen then board a little bit, and that would probably give us enough space to add the standoffs back in.

Universal MicroSD Card Adaptor 1.PNG

Yes. That looks like what I envisaged but I would keep the Stand-off pillar and let Master users leave the User Port Header off.

Thank you for indulging me in this quest. Working KiCAD from only a YouTube tutorial was testing my attention span and my capabilities! I will send you a PM ...

Robin

[KenLowe]

Dave added a couple of "adds" to the Mainboard to bring Vcc out on previously unused Pin 26 of the Printer Port so the adapter would not need external power. However, I would keep the Vcc and Gnd header on the adapter to enable it to power your 1MHz Bus Level Changer Board. Note also the PA7 Input signal added to previously unused Pin 25.

That's me added power to the Printer port pin 26. I already had pin 25 wired, so I think I have everything in place. The only thing is, I don't think we're going to get this to work very well.

The main issue I have is that the PCB can't be any wider than the beeb connector at the beeb connector, otherwise the PCB will clash with the lugs on the beeb connector. Once clear of the lugs, I can then widen out the PCB, which is what I do with the 1MHz level shifter. Here, I can then extend the PCB out long enough to fit the MicroSD Card Adaptor and be able to include the standoffs. It's made a bit more complicated by the fact that the MicroSD Card Adaptor is about the same width as the 26 pin connector for the printer port.

To make this work for both user and printer port, I really need to increase the depth of the board and allow the MicroSD Card Adaptor to sit in the middle completely free of the user and printer port connectors (instead of on top of the connectors). Currently, the board is limited to 27mm depth to make it fit into the Master, and even then it's a tight squeeze, so there's no opportunity to increase the depth to make this work for the Master. Even with the beeb, if I increase the depth, I then start running into problems because of the slope in the well. It might just about work, but everything is stacking up against us.

Yes. That looks like what I envisaged but I would keep the Stand-off pillar and let Master users leave the User Port Header off.

Ha. That's being a bit optimistic. With the current depth of board, I can't make the PCB long enough to take the standoffs, without it clashing with the lugs on the beeb connector. I believe you would only be able to use a single standoff, and that standoff would need to go into the opposite side from the side that's being plugged in to the beeb. That would work fine if you didn't want the board to be reversible. But the fact you want it reversible, means that the PCB would clash with the lugs. So, the only solution is to increase the depth of the board. I hope I'm making myself clear. I'm finding it difficult to describe the issue!

TBH, the simplest solution would be to have a separate board just for the printer port.

[Wheel_nut]

Hi Ken,

Would thr Printer Port connector fit into the Master if you extended the Board width to avoid snagging the Clips and with the Standoff(s) in place, IF ... you left the User Port off the Board for the Master Printer Port Applocation?

If that is feasible (and I cant tell because I don't have a Master), I would prefer the wider Board and Standoff(s) in place. This would give the best versatility for Beeb Users but still be usable if customised for the Master,

What do you think? .... Robin

[KenLowe]

Here's a couple of photos showing the current board plugged into the Master. You could only ever have either the user or printer port connector soldered on at any one time.

See how I can't extend the pcb at the user port end because the lugs are in the way. That means, when you turn the board around to plug into the printer port, you don't have the section of pcb you need for the standoff.

[Wheel_nut]

Here's a couple of photos showing the current board plugged into the Master. You could only ever have either the user or printer port connector soldered on at any one time.

OH!!! I didn't realise that the Master connector Well was so narrow! I can see that my suggestion of widening the Board would definitely not work with the Master. Are you saying that a Wider Board WOULD work with the Master IF only one Header was fitted? If this would still allow a Stand-off to be accomodated, I would go with that design.

See how I can't extend the pcb at the user port end because the lugs are in the way. That means, when you turn the board around to plug into the printer port, you don't have the section of pcb you need for the standoff.

Just a final thought. ... I am not sure that Dave's P/MMFS design is actually implemented for the Master. I will check on Github and edit this Post with the answer.
EDIT: Yes there is a P/MAMMFS ROM in the v1.44 Package but the Board Rework in the discussion thread only shows the Beeb Mainboard.

[Wheel_nut]

Having done some measurements, I think that the minimum width of the double ended Board has to be 44mm (42mm at a push!).

this comprises of:
10mm set-back to avoid the Clips at the User Port end
24mm for the width of the MicroSD Card (to allow for the stand-offs)
10mm set-back to avoid the Clips at the Printer Port end

This is my poor attempt at a drawing of the outline of the Board:

Sorry for my late night brainstorm but it just struck me that the 10mm setback is only required on the User Port side in order to acccommodate the standoff pin on that side. The MicroSD Card could overhang the clips on the Printer Port side as it does on your current design. Thus, the width of the Board could be reduced by 10mm to 34mm which may still fit in the Master with only one Header fitted. This would be my definite preference!

[KenLowe]

Are you saying that a Wider Board WOULD work with the Master IF only one Header was fitted? If this would still allow a Stand-off to be accommodated, I would go with that design.

No. I've attached a copy of the board layout, and overlaid the MicroSD Card Adapter on top to try and better explain the issue. I'm also showing the 4 mounting holes on the MicroSD Card Adapter. You will notice that two of the mounting holes clash with 26 way (printer port) and 20 way (user port) connectors. The other two are sitting above free space. If I extend the pcb into that free area, the pcb would clash with the lugs, regardless of whether you plug into the user port or printer port.

The problem is trying to design a board that can be plugged into either user or printer port (even if you don't solder on one of the connectors). If I'm designing the board to only plug into one connector, then I can extend part of the pcb, which would allow one of the mounting holes to be used. This is what I showed earlier today with the updated user port version.

As I said before, if depth wasn't a problem (as in the beeb), then we could probably make something that works. But the problem with the beeb keyboard well is that it slopes, which again makes things more difficult.

The easiest solution is to just build a dedicated printer port adaptor, like this: viewtopic.php?f=8&t=20843.

[KenLowe]

Having done some measurements, I think that the minimum width of the double ended Board has to be 44mm (42mm at a push!).

this comprises of:
10mm set-back to avoid the Clips at the User Port end
24mm for the width of the MicroSD Card (to allow for the stand-offs)
10mm set-back to avoid the Clips at the Printer Port end

Yes, exactly that. And with the board being that deep, it'll only fit in the beeb, and even then you'll start running into problems with the slope of the well.

An odd board layout like this might just about work, but the little dog leg is very skinny (4mm) and would probably snap off. I've not checked the beeb or master to see if that little cut out would be sufficient to clear the lugs:

[Wheel_nut]

No. I've attached a copy of the board layout, and overlaid the MicroSD Card Adapter on top to try and better explain the issue. I'm also showing the 4 mounting holes on the MicroSD Card Adapter. You will notice that two of the mounting holes clash with 26 way (printer port) and 20 way (user port) connectors. The other two are sitting above free space. If I extend the pcb into that free area, the pcb would clash with the lugs, regardless of whether you plug into the user port or printer port.

I would be very happy with your design as shown, without the Stand-off support. I would use a stick-on pillar attached to the Beeb Connector Well base to support the MicroSD Card. I think you are saying that this Board would also fit a Master if only One Header was fitted so it is an acceptable compromise for all. (My PM offer still stands.)

The problem is trying to design a board that can be plugged into either user or printer port (even if you don't solder on one of the connectors). If I'm designing the board to only plug into one connector, then I can extend part of the pcb, which would allow one of the mounting holes to be used. This is what I showed earlier today with the updated user port version.

I think that your V2 User Port Extender with Power take-off still has its application for which it was designed and the stand-off support is a considerable improvement on the V1.

As I said before, if depth wasn't a problem (as in the beeb), then we could probably make something that works. But the problem with the beeb keyboard well is that it slopes, which again makes things more difficult.

The easiest solution is to just build a dedicated printer port adaptor, like this: viewtopic.php?f=8&t=20843.

Now I hadn't seen JasonStonier's design - I must have blinked! If you decide not to proceed, I will buy some of his boards though they don't solve the stand-off support issue.

Robin

[Wheel_nut]

Having done some measurements, I think that the minimum width of the double ended Board has to be 44mm (42mm at a push!).

this comprises of:
10mm set-back to avoid the Clips at the User Port end
24mm for the width of the MicroSD Card (to allow for the stand-offs)
10mm set-back to avoid the Clips at the Printer Port end

Yes, exactly that. And with the board being that deep, it'll only fit in the beeb, and even then you'll start running into problems with the slope of the well.

An odd board layout like this might just about work, but the little dog leg is very skinny (4mm) and would probably snap off. I've not checked the beeb or master to see if that little cut out would be sufficient to clear the lugs:

Hi Ken, I hope that my persistence with this isn't annoying you

In studying your Layout, it just struck me that the 10mm setback is only required on the USER Port side in order to acccommodate the standoff pin on that side. The MicroSD Card could overhang the clips on the Printer Port Port side as does on your current design. Thus, the width of the Board could be reduced by 10mm to 34mm which may still fit in the Master with only one Header fitted. This would be my definite preference!

This would definitely work for the Beeb but I can't verify it for the Master. See the sketch below. I have overlaid the MicroSD Card in Red and I believe that you said earlier that the maximum width available on the Master is 37mm so it is a tight squeeze and would only fit on the Master with ONE Header fitted.