NBTV/SSTV-625 Up Converter MkIII

Where it all started as far as most are concerned and saw heavy use from the 60s through to the 80s. Colour and Hi-res modes have unfortunately pushed this system into the backwaters of SSTV. Time to resurrect interest in this simple analogue system.

Re: NBTV/SSTV-625 Up Converter MkIII

Postby Andrew Davie » Wed Dec 02, 2020 1:35 pm

I actually use/prefer a company called PCBWAY, these days.
They're super-quick, check the board is correct/valid, and charge me just $5 for a 10 piece sample/prototype run.
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Re: NBTV/SSTV-625 Up Converter MkIII

Postby Steve Anderson » Thu Dec 03, 2020 4:55 pm

Thanks for the tip Andrew, will certainly give them a try when/if I get to that stage.

I watched a few tutorials yesterday regarding the Eagle PCB software, it's a lot to take in but I'll give it a bash...when I dabbled with it 2-3 years ago I approached it from the wrong angle/wrong order.

If/when I/we get to that stage I expect this to be a double-sided board of Eurocard dimensions (160x100mm) with an optional DIN41612 edge connector but still retaining wire-in terminals and mounting holes in the corners, you choose which to use...that should be quite enough to accommodate everything except the front-panel controls, external signal connectors and power transformer/fuse.

Also with thru-plated holes, solder resist and silk-screen.

The pictures show 32-pin versions of a DIN41612 connector, but they're also available in 64, 96 and 160-pin varieties. Usually the male version is fitted to the PCB. They've been around since the 70s and there's still a huge demand for then. All on 0.1"/2,54mm spacing. Easy to get from the usual distributors, with either wire-wrap, PCB or solder-bucket lead-outs.

It might be possible to include an alternative 25-pin D-type at the other end of the PCB, again, you choose. But although they might look it, D-type pins are not on a 0.1"/2,54mm spacing. But with today's software that's no issue at all.

Steve A.

Though none of the above matters until I get the prototype operational!
Attachments
DIN41612 Example.jpg
DIN41612 Example.jpg (27.31 KiB) Viewed 441 times
DIN41612 Example 2.jpg
DIN41612 Example 2.jpg (6.15 KiB) Viewed 441 times
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Re: NBTV/SSTV-625 Up Converter MkIII

Postby Steve Anderson » Sat Dec 05, 2020 1:43 pm

Just got an on-line quote from PCBWAY for the board for this...

100x160mm (Eurocard), double-sided, solder resist, through-hole plated, drilled, silk screen, tinned, quantity 10,....US$46 for the 10 PCBs plus US$21 DHL shipping to here. i.e US$67, US$6.70 per board. Turn around, well under a week*, probably 4-5 days. Add a little bit more for shipping to you. Sounds good to me!

*That's assuming there are available flights for cargo. Mail from the UK to Thailand used to be an average of 3 days, now it's at least 2 weeks!

At the same time as shipping the board add in the two pre-programmed and tested micros, around US$5.60 for both micros. All the other components you should be able to get from the usual suppliers.

Steve A.

I'll create a parts-list with examples from a couple of suppliers so they'll fit correctly into the board, probably RS and Farnell/Element 14. I'll be avoiding SMD parts unless there's no option. So far all components are through-hole types.

I suggest using IC sockets for the two micros for potential software updates, the others are optional...though I do suggest using them.
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Re: NBTV/SSTV-625 Up Converter MkIII

Postby acl » Sat Dec 05, 2020 6:36 pm

Sounds good to me Steve. Im looking forward for future updates.

Regards Chris Lewis
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Re: NBTV/SSTV-625 Up Converter MkIII

Postby Steve Anderson » Sun Dec 06, 2020 5:39 pm

Hmm, those DIN41612 connectors are NOT cheap! The mating pair alone will cost almost the same as the PCB and all components on it! For industry, fine, but not for us impoverished hobbyists. Time for plan B. Even those PCB mounted screw terminals could be viewed the same way, quite a few connections are required to/from the PCB, around 20-25. I'm not keen on those ribbon-cable headers either unless the ribbon cables are bought pre-made.

More to come...and suggestions welcome...

Steve A.
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Re: NBTV/SSTV-625 Up Converter MkIII

Postby Andrew Davie » Sun Dec 06, 2020 6:27 pm

I spotted male and female DIN41612 on AliExpress in lots of 10 for US$12 and US$9.60 with free shipping. That doesn't seem too expensive...
e.g.,

https://www.aliexpress.com/item/33014127986.html

https://www.aliexpress.com/item/4001272473466.html

I didn't hunt for the absolute cheapest; just the first reasonable ones I saw.
Were these what you were looking for?
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Re: NBTV/SSTV-625 Up Converter MkIII

Postby Steve Anderson » Sun Dec 06, 2020 7:20 pm

Andrew Davie wrote:Were these what you were looking for?

Yep, and that's a much better price, even retail here they're far cheaper than the UK.

At this rate I may as well supply the whole kit, everything except off-board stuff, pots, switches, LEDs, external connectors and the transformer....which I'm willing to do. If anyone is interested in an 'almost complete' kit let me know. It's not beyond the realms of possibility...

Remember, this is for NBTV and SSTV...

Steve A.
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Re: NBTV/SSTV-625 Up Converter MkIII

Postby Steve Anderson » Tue Dec 08, 2020 3:49 pm

Further update...If the read processor is changed (IC102), and the external RAM (IC201/2) both deleted, the unit becomes NBTV only...for those not interested in the SSTV mode. There's enough RAM within the changed read processor for NBTV, but the external RAM is required for SSTV. If later the SSTV mode is required both IC201/2 can be installed, No changes/updates required to either processor software or hardware changes.

If the external RAM (IC201/2) are absent and SSTV mode selected, the unit will simply stay in NBTV mode and warn the user, no damage done.

There are a few other useful advantages in changing the read processor anyway...which I'm tempted to go with...design, as always, is an iterative process...thankfully I'm not constrained by commercial interests here, though I want to keep the final unit to a sane cost and complexity...

Steve A.
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Re: NBTV/SSTV-625 Up Converter MkIII

Postby Steve Anderson » Fri Dec 11, 2020 3:01 pm

Right, final decision made, IC101 & IC102 are both PIC18F26K22s, 28-pin 0.3" DIL. The pre-programmed versions will have a stripe of coloured nail-varnish to identify which is which. The write processor (IC101) will have a red stripe at the opposite end to the DIL package 'notch', the read processor (!C102) will have a green stripe likewise. This will be marked on the schematic as well as the board layout diagram.

Unfortunately multi-coloured silk screening comes with a significant cost penalty...so I'm not going to use it.

So I'll have to go out and buy some red and green nail-varnish - could be interesting!

Nail-varnish is often used when PCBs need a bit of 'knife & forking' to cover up minor track errors.

*****************************
Added later...I think the hardware design is now a 'job done', time to build up the prototype, write the code and get the PCB underway.

NBTV only...not including PSU...

2xPre-programmed PIC18F26K22s (28-pin DIL)
1xDAC0800 or similar (16-pin DIL)
That's it!

SSTV & NBTV..not including PSU...

2xPre-prorammed PIC18F26K22s (28-pin DIL)
2x23LC1024 (8-pin DIL)
1xDAC0800 or similar (16-pin DIL)
That's it!

In both cases, add in 3xBC547Bs, 1x7812, 1xLM317 and 1x79L12. For video output and power supply, no heatsinks required. The rest are all passive components.

Steve A.

As this is a significant change to the original MkIII I'm gonna call it the MkIV and create a new thread when I need to post again...the next new thing for me will be doing a PCB...here goes...

******************
For those in 525 areas I'll look into it but most modern TVs/monitors seem to accept both...even my (probably) 30-year old JVC CRT TV does!
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Re: NBTV/SSTV-625 Up Converter MkIII

Postby Harry Dalek » Fri Dec 11, 2020 7:25 pm

OH dear home made PCB over the years i could never bring my self to try it ,i suppose these days you could get a etching circuit board kit but still have to drill the holes i suppose ?
The electromagnetic spectrum has no theoretical limit at either end. If all the mass/energy in the Universe is considered a 'limit', then that would be the only real theoretical limit to the maximum frequency attainable.
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Re: NBTV/SSTV-625 Up Converter MkIII

Postby Steve Anderson » Sat Dec 12, 2020 11:56 am

I'm not making the boards myself, I make up the required Gerber files in software, send them to a PCB manufacturer and a few days later you get them delivered. No mess, no hassle and professionally done. It's probably cheaper than buying all the stuff needed to DIY them.

PCBWAY quoted for 10-off, 160x100mm board (Eurocard), double-sided, drilled, plated-through, solder resist, silk-screen printed for US$67 for the 10, US$6.70 each including DHL delivery.

As an example here's the blank PCB for Andrew's 'ArduinoVisor', It's around 60x97mm with all the options mentioned above. Though I don't think this was done by the same company I intend to use, I expect the same sort of result. Sorry about the reflection, the boards finish is very smooth...

Steve A.

ArduinoVisor PCB.jpg
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Re: NBTV/SSTV-625 Up Converter MkIII

Postby Harry Dalek » Sat Dec 12, 2020 1:56 pm

OH i see Steve ! i have not seen Andrews Board before love the name ; )
Have you named your board Steve ? Need Albert he's great at naming projects :wink:
Look into your Board for sure once it is ready .
I wish there was some thing like a AURORA STANDARDS CONVERTER or a baby version that could take over from what a pc can do you would think using a PC with something connected would make it easy i have no idea ....i am lost when it comes to this stuff.
Any case keep going on this one Steve .
The electromagnetic spectrum has no theoretical limit at either end. If all the mass/energy in the Universe is considered a 'limit', then that would be the only real theoretical limit to the maximum frequency attainable.
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Re: NBTV/SSTV-625 Up Converter MkIII

Postby Steve Anderson » Sat Dec 12, 2020 9:52 pm

No, I haven't really thought of a 'name' for it beyond the rather sterile and unimaginative "SSTV/NBTV-625 Up-Converter" possibly with "Mk IV" tacked on the end. As it is a cross-converter how about, "Mr. Angry Mk I"?

After all, some of my previous projects tended to be female orientated, "The Vixen", "The Hellcat", about time the guys had a bashing!!

Suggestions welcome...

Steve A.

Those based in the UK may remember Steve Wright's "Mr. Angry" pieces inserted into his Radio 1 radio programs in the 80s...catchphrase..."I'm so angry I could slam the phone down"...and of course he did...and you never were quite sure what he was angry about!
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Re: NBTV/SSTV-625 Up Converter MkIII

Postby Steve Anderson » Sun Dec 13, 2020 4:16 pm

Harry Dalek wrote:I wish there was some thing like a AURORA STANDARDS CONVERTER or a baby version...

Well, in a way this is, it's nowhere as flexible as an Aurora but it handles the two (possibly three) modes that I'm interested in, hopefully a few others are interested too! That is broadly Copthorne McDonald's SSTV-625, NBTVA Standard NBTV-625 and possibly Chris Long's "Half NBTV"-625 as I have dubbed it.

After this I'm considering a similar version that can handle the PD-120 SSTV mode (maybe other PD modes too), the type of SSTV used aboard the ISS. Receive on 145.800MHz FM. Schedule announcements are made well in advance so you can determine if you're in the right place on the planet to receive the signal.

Info here on PD modes from the developers site:-

http://classicsstv.com/index.php

An ISS tracker website:-

http://www.isstracker.com/home

Steve A.

Note:- For the colour PD modes your TV/monitor will need YUV inputs, often marked Y, Pb, Pr or something similar, Y, Cb, Cr. Make sure it does first! Most made in the last decade do. In Europe they may be within the SCART connector, but I hope not. I do not intend to add a PAL (or NTSC) colour encoder...
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Re: NBTV/SSTV-625 Up Converter MkIII

Postby Steve Anderson » Sun Dec 13, 2020 6:41 pm

What I should perhaps also think about is some form of SSTV generator that turns a standard monochrome BMP or TIFF file into the 8-second format. I've already done it to generate the signal/pictures for the previous up-converters, but it could do with a lot of simplification and rationalising. More later...

Steve A.
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