Narrow-Bandwidth Television Association

Not sure if this is quite the right place to put this, but...

If anyone is contemplating building up any of the stuff I post on this site which uses PIC processors, the problem might be programming them.

If you can program the devices yourself, then that's easy. When the code is complete I'll post the .asm and .hex files within the devices thread, .lst file too if desired. They're usually quite small files, well under 100kB.

If you can't program them yourself I'll do it for you and pop them in the post, airmail. The chips are much cheaper here than in Europe, Oz or the US, postage isn't much as they're small and lightweight, add a 'Jiffy-bag', some conductive foam stuff and you're done.

Prior to shipping I would 'burn them in' for a day or two.

I'll find out what the postage costs are as we have a post office just a 10 minute walk from us.

Now, I've tried to get the conductive foam here without much success. Anyone know a supplier? See photo.

All the above done at cost,,,

Steve A.

Steve Anderson wrote:Now, I've tried to get the conductive foam here without much success. Anyone know a supplier?

eBay shows several sources available - at least here in the UK - including from China with free postage, but I don't know what the situation is regarding posting to Thailand.

I am off cause interested in the project Steve but i can't program the chip dumb dumb i am ..i need to see the updated schematics again ,depends on any other chips if its possible to make .
i recall you posting up something but have not been able to find it to study the schematic .

Dave, thanks, I'll have a look around e-bay...I tend to forget the obvious!! Post from China to here is usually no problem.

Harry, others too, don't even think about building the MkIII up-convertor yet, I haven't even powered the prototype up yet, it will change, for sure, as time goes on.

I like others to see the evolution of the device, the reasons for the choices I make...and also the mistakes...

I'll program a couple of chips for you Harry when the software has been thoroughly tested. That also hasn't even been started on. At the moment the whole thing is a paperwork exercise...

Steve A.

Steve Anderson wrote:
Harry, others too, don't even think about building the MkIII up-convertor yet, I haven't even powered the prototype up yet, it will change, for sure, as time goes on.

I like others to see the evolution of the device, the reasons for the choices I make...and also the mistakes...

I'll program a couple of chips for you Harry when the software has been thoroughly tested. That also hasn't even been started on. At the moment the whole thing is a paperwork exercise...

Steve A.

No problems Steve ...I was thinking did i miss a few posts ! Glad not as i like to keep up to date on your project .

Thanks Steve i would need a programmed PIC that would be the big problem other wise .

I will keep on watching it evolve .

Steve Anderson wrote:Post from China to here is usually no problem.

Yes, it did occur to me that you're physically a lot closer to China than I am, but the political situation regarding international transactions can also come into play at times. Delivery might even be quicker than sending stuff half way round the globe.

I've ordered a few things from China fairly recently, not generally electronics related, but with no problems...we'll see how it goes. That foam is cheap enough anyway even if it all falls through...if it does I'll find another non-China source...there's no panic...

Steve A.

Steve, I have seen CMOS chips sent on a piece of (white) polystereen, wrapped into sheet of aluminium (house hold) foil. As that metal foil is very conductive the chips are protected, and I guess even better than on the rather high ohmic black foam.

Yes Klaas, I have come across that alternative before. If the conductive foam proves to be too much trouble I'll use that.

Steve A.

The next thing I need to think of - and this is really a no-brainer - is labeling the chips without the labels falling or peeling off. They're both the same type of chip, but with different software within each...you really don't want to mix them up! An indelible marker perhaps? Trouble is my handwriting is horrendous! I guess I could manage just '101' and '102'....the two IC numbers in question...

Steve A.

Presumably, your quantities would be too low to justify splashing out on a Dymo label printer*, though I'm sure you could find other things to label with it.

*N.B. The listing shown is just used as an example. No doubt more appropriate suppliers are available in your neck of the woods.

Yep, possible, but if the labels are the same as the ones we used decades ago, they fall off after a while as the adhesive gives up...

I'll come up with something, but thanks for the thought...

Steve A.

Steve Anderson wrote:if the labels are the same as the ones we used decades ago...

Are you thinking of the old-fashioned embossed tape? If so, the answer is "no", Dymo has moved on considerably from there. Modern machines use a microprocessor to produce neat printed labels in a selection of sizes. I don't currently own one myself, but folk I know who do have applied labels to a variety of surfaces over recent years without them peeling off, despite being subjected to harsher conditions than would be expected on the surface of a chip.

Al foil isn't very conductive until you dig through the oxide layer, and I'm dubious about a chip pushed into foam maintaining a gas tight contact between the foil and pins during shipping. Expanded polystyrene seems like the worst possible thing to put anywhere near a static sensitive device to me.
I realise this used to be "standard practice", but the same can be said for a lot of things.

I tend to agree, the Al on poly could be hit-and-miss, but it's better than nothing. I remember the days when you just had to LOOK at a CMOS or MOSFET chip and it would die! They're far more rugged than the used to be, but when you're putting then in the post you have no control over their environment. The dry air at high altitudes in an aircraft are ripe for generating static.

Remember those dry winter mornings in Europe, blue sky, with frost on your car, you walk up to it, touch the door-handle and _ ZAP!! Actually no different with a light aircraft. There are also conductive plastic bags, transparent, but with a 'smokey' appearance, generally in larger sizes for shipping completed PCBs.

Possibly the best belt-and-braces approach is the conductive foam with an overwrap of Al foil...

Steve A.

Is 'overwrap' a new word I've just created?

Is it correct that X-rays will go through Aluminium? I think so. Don't want any hassle with Airport Security...Wiki tells me it can...