Who else is building a Beeb from scratch?

[!FOZ!]

I started this thread to find out if anyone else in this community is building a Beeb from scratch using the replica BBC Model B PCB. We can see that that Mathew has taken the plunge with a great 4 part series (https://youtube.com/playlist?list=PLkl_ ... Yra-FRu5gN). I also recall seeing a few comments from others that plan to. So how is everyone getting on?

In my case, my goal is not quite a 100% replica, rather in the only way I can describe it a Beeb Home Console box? I want to keep the PCB standard, so could be placed in a regular case with regular keyboard etc. However inspired by the Beeb in a PC case project I wanted to make the form factor smaller and basically have wireless keyboard (modern mechanical of course), joystick etc, with as many retro upgrades, co-pro, hd emulation etc but all in a single box with a power, HDMI output and USB ports only. In the world of PC’s these are called HTPC (Home Theater PCs). Anyway if your thinking huh? Is this guy mad? Yeah probably! I am just at the start of the build and taking my time - and have not yet found a good case.

If you are building, please share your story, especially if you are further down the road and have tips and tricks for others.

Attached are some pics of progress so far…

[!FOZ!]

I am fitting the A labeled capacitors, in the BOM these are 33nf. My meter shows most of them as 33nf, some are 34nf and a few 35nf. Is this an issue to the beeb? It’s in tolerance for the data sheet for the components from mouser.

[arg]

I am fitting the A labeled capacitors, in the BOM these are 33nf. My meter shows most of them as 33nf, some are 34nf and a few 35nf. Is this an issue to the beeb? It’s in tolerance for the data sheet for the components from mouser.

10% accuracy on decoupling capacitors is luxury! Especially as yours appear to be on the higher side, which is better for this application.

[!FOZ!]

I am fitting the A labeled capacitors, in the BOM these are 33nf. My meter shows most of them as 33nf, some are 34nf and a few 35nf. Is this an issue to the beeb? It’s in tolerance for the data sheet for the components from mouser.

10% accuracy on decoupling capacitors is luxury! Especially as yours appear to be on the higher side, which is better for this application.

Ah good to know. Thank you.

[wiggy]

My meter shows ...

And add probably a couple of percent extra variation for the meter accuracy, and some more for how you've draped the leads!

Looks like you are doing quite well!

[!FOZ!]

All 76 33nf capacitors fitted!

I am not fast at this and cleaning as I go probably is not the fastest either. Plan to work through the BOM pretty much from top to bottom - smaller components first. Having the standoffs fitted on either side has helped a lot manipulating the board and components as well (thanks to one of the many YouTube videos I watch for that tip).

p.s some of the fittings are showing not all the solder has flowed to the surface, yet below has the desired concave look. Views on reflowing those to top up the solder to flow to the top of the board or no?

[eelco108]

I'm doing two at the same time (as most of ones time goes into sorting out resistor values etc.), and got as far as:
- all wire connections, flat resistors and flat diodes
- all decoupling caps (yes, quite a lot of them, indeed!)
- all IC sockets
- next step: the flatcable connectors, and then the standing resistors and diodes

So they are starting to look nice, but still some way to go! But it is quite fun to do, as long as you take your time. Don't rush this!

I'm including the Econet components - better to do it now than later. You don't need to insert the Econet ICs themselves yet, if you do not plan on using it.

The keyboard is probably the hardest part, but I think I've got two complete ones now (need to test them - one is quite dirty).

[!FOZ!]

I'm doing two at the same time (as most of ones time goes into sorting out resistor values etc.), and got as far as:
- all wire connections, flat resistors and flat diodes
- all decoupling caps (yes, quite a lot of them, indeed!)
- all IC sockets

Thats great progress and great use of time to get two done at once! Are you ok sharing some pictures? I know an existing Beeb board is a good reference - just thinking would be useful for others on this thread to see how folks have applied laying things out on the new PCB. I personally stare at that cluster in the top right and think him....

The keyboard is probably the hardest part, but I think I've got two complete ones now (need to test them - one is quite dirty).

Yeah for my goals thats not such an issue see here viewtopic.php?f=3&t=27174. I also think there is one on eBay at present btw.

[1024MAK]

I’m not building a new Beeb board, but have built countless other projects.

I nearly always start with the lowest height components first, then work my way through the different sizes.

With through-plated boards, as long as there is plenty of solder filling the hole, it does not matter if it does not show on the top side, or if you don’t get a perfect cone on the bottom.

Good luck

Mark

[eelco108]

Thats great progress and great use of time to get two done at once! Are you ok sharing some pictures?

Sure! I'm currently in Chile, but back in two weeks, so will make some pictures then.

I'm hoping to be done by the end of the year (well, at least one of the two boards, with all sockets populated - some IC are harder to get then others ...). A Meanwell power supply will bring it to life, if all goes well.

[Rich Talbot-Watkins]

What are homebrew Beeb builders doing for parts which are no longer available, like the Video or Serial ULAs? Raiding old dead Beebs for parts, or are there modern alternatives à la VideoNuLA?

[eelco108]

Both, in my case.

I have a spare (original) Video ULA, and a VideoNULA. And two boards

It just takes time tracking down the rare ones. I don't want to salvage my original beebs, even though I have five of them

My thought is that some of the old beebs will eventually get too many faults, and then hopefully the remaining working parts can be used in the 'new from scratch' ones. But that is mere hope, not a plan ...

[thedark]

I am building the same board with the same missing track.
I have some old masters and 2 beebs.
One i wil keep as spare working and the other was econet a mess. I used all ic from that board. Have buy some parts from aliexpress and some from mouser and a store nearby.
I starten to strip the old bbc. And some parts are needed because you cant buy them anymore.
I spend 4 hours of strippen with hot airgun. Zo can i spare some chips as the ula. I do not use the other parts bacause they damage. The din sockets are also not easy to get. The domino socket is rare and must come from a donor board. Rest of connectors are at aliexpress .
The resistors also from there...

Well i am hoop to get some parts to build the board.. fingers crossed...

[!FOZ!]

The domino socket is rare and must come from a donor board

Yes I conceded to ordering a regular 5 pin DIN for that, the footprint is the same (i think) and I will simply adapt whatever lead or connection I want to make to it in the future. Rather this than an empty place on the PCB!

[!FOZ!]

What are homebrew Beeb builders doing for parts which are no longer available, like the Video or Serial ULAs? Raiding old dead Beebs for parts, or are there modern alternatives à la VideoNuLA?

As per others for VideoULA I have a spare (from a prior Nula upgrade) and of course can apply another Nula - however I plan to use RGB2HMDI and it does not play so nice (having fiddled with settings a lot in my other beebs) - so holding off on that for now - hence using my spare.

For Serial ULA, i was luck enough to find one here they may still have stock > https://www.cjemicros.co.uk/micros/indi ... -SERIALULA

[thedark]

I had an idea to put a 5 din in and make a litle cable to connect orginal bbc rs 423. So that this not a problem.
This is stil to buy. So you had same idea nice. Some parts i stil got from donor board. Bud most parts are New.
Except the main ics Cummings from donor. But its a lot of work and hope its gonna work out. A friend of mine is building his own board. Looks very nice and very red bud is already working. I have a New chest where i can build it in with New suroundings.
Looks also very good

[!FOZ!]

I had an idea to put a 5 din in and make a litle cable to connect orginal bbc rs 423. So that this not a problem.

Yes, very good idea to create small adapter "cable", as I did find at least a few domino female sockets for cables - I'll go order some of them now actually. Nice share - thank you!

But its a lot of work and hope its gonna work out.

It is, but we must take our time and be careful, savor the process and enjoying a successful outcome is assured - especially with all the friends on StarDot here!-Realistically I am expecting to require some debug / diagnosis as well - but maybe not - lets see together!

A friend of mine is building his own board. Looks very nice and very red bud is already working.

Really that is interesting, is this an alternative BBC PCB board design then? Any pictures?

[!FOZ!]

Sure! I'm currently in Chile, but back in two weeks, so will make some pictures then.

Safe travels and look forward to the pics when you return. I spent about 3 months getting all the parts to now start the build process, which I also expect to take at least 3 or months via on/off weekend working - maybe some component testing during work evenings.

[thedark]

I have picture of his work so far.
Its a issue 4 but this is his work of art mabe he wil get to this forum. But he has a litle time and to mutch to do

[Andrew_Waite]

Does a new Beeb need a serial ULA to function? I would think that the lack of a functioning Serial and Cassette ports would not be a big problem.

Does the MOS poll this chip and could the MOS be modified to remove this?

[wiggy]

The domino socket is rare and must come from a donor board.

It might be worth contacting Cliff https://www.cliffuk.co.uk/ and/or Deltron https://www.dem-uk.com/deltron-components/ - both in the UK - who made these in the past: it's possible they've either got a few knocking around in a cupboard or might even still have the tooling to do a short run if there's interest (it being very close to the 8-pin version, which they both still make, but the centre pin is slightly offset in the 8-pin)

[BigEd]

Does a new Beeb need a serial ULA to function? I would think that the lack of a functioning Serial and Cassette ports would not be a big problem.

I think you're probably right, but I have a vague idea that some game (or copy protection system) might use the serial to produce an interrupt - as a short-term timer, in effect.

[baz4096]

Fingers crossed I should have a modest supply of the 5pin DIN 360 domino/dice connectors in a week or so. Only down side is they are grey, not black. Shouldn’t be too pricey either. Also I will have some new keyboard cables that use the same pitch ribbon cable as the originals, albeit with a slightly different connector. Will post in here when I have photos.

[!FOZ!]

Fingers crossed I should have a modest supply of the 5pin DIN 360 domino/dice connectors in a week or so. Only down side is they are grey, not black. Shouldn’t be too pricey either. Also I will have some new keyboard cables that use the same pitch ribbon cable as the originals, albeit with a slightly different connector. Will post in here when I have photos.

Nice!

[Ukwebb]

Foz, If i may ask, what is the board you have plugged in the PI ( with the ribbon cable etc )

also any info on that power board, that looks like it could be quite useful

thanks

[!FOZ!]

what is the board you have plugged in the PI ( with the ribbon cable etc )

Sure it is called USB4VC (Vintage Computers) from dukeNukem. Basically it emulates the keyboard, analogue port (with future provision for the user port) and with the Pi allows you to connect modern wired/wireless USB keyboards, joysticks and mice. More details in this thread, viewtopic.php?f=3&t=27174. Note I had to construct the BBC daughterboard as thats not for sale presently, as its still a prototype. However the creator very very kindly supported my own build process as he has open source the entire project.

also any info on that power board, that looks like it could be quite useful

Yeah, it is ATX4VC, from the same supplier also dukeNukem, https://github.com/dekuNukem/ATX4VC. My board appears to be now an older revision. Looks like his latest has a daughter board to make some of the fancy features option if all you want is the power. You can purchase the current ATX4C from his page https://www.tindie.com/stores/dekunukem/.

Overall I am blown away with his products, both in design and quality.

P.S. In addition to this he shared over in his public discord (https://discord.gg/rQPhVvQd) a few pics on an even smaller and dedicated BBC board he is working on (attached pics for ease).

[thedark]

The first round has been done.
Tomorow the ic sockets and the idc connector on it. And some small stuf.
Then i have to wait for next batch of parts

Some parts placed.

[!FOZ!]

The first round has been done.
Tomorow the ic sockets and the idc connector on it. And some small stuf.
Then i have to wait for next batch of parts

IMG-20230709-WA0001.jpeg

[!FOZ!]

So I am testing all my capacitors before putting them on, double checking etc etc. C58, requires a 0.47nf (470pf) and on my multimeter it returns 0.53nf. Is this an issue that its 0.06 adrift? Here is the actual component https://www.mouser.com/ProductDetail/TD ... XESA%3D%3D. I know I am being super paranoid likely here

[1024MAK]

Capacitors, like many other components have a tolerance. They should be within the tolerance range.

But you also need to take into account how accurate your meter is and it’s resolution. Plus estimate the parasitic capacitance of your test setup. Parasitic capacitance affects small value capacitors, and can be significant if your meter uses leads.

In the real world, in the vast majority of applications (especially decoupling and coupling), a larger capacitance will do no harm. And C58 is being used as a coupling capacitor. So don’t worry about it.

Mark