Humble Pi?

[Tim Streater]

No money for that sort of stuff when I was a boy. This was 50 years ago. I had to rely on my brother, who was in the Navy, brining home stuff that was otherwise going to be thrown away.

[Mark]

That's great. I guess I was looking at the pi from the school's perspective when I wrote that comment. I'm sure schools would prefer something that just works without having to spend time fixing soldering issues. I wonder how many teachers can actually use a soldering iron?

[S Viemeister]

What an absolutely delightful typo! (Was it deliberate?)

[Tim Streater]

Sorry, no.

[John Rumm]

The type of soldering required for the Pi would put its construction beyond the vast majority of potential constructors anyway. (the main SoC is a BGA device with a BGA top hat RAM module on top of it!)

The makers have already said that a case will become part of the deal in due course. Price to remain unchanged...

[Bob Eager]

I built a clone Heathkit amp. Borrowed the manual off a friend and built my own from scratch.

[Huge]

I'm dead impressed with all this willy-waving, BTW. For some reason, electronics is a bit of a dead zone for me - the most complicated thing I've ever built was a 555 based Morse code oscillator.

[The Natural Philosopher]

well since it was in fact my living I have built everything up to and including complete radio/hifi sets and discotheques...and put the designs into production..

Can be arsed with digital though. Dead boring really at the hardware level.

[Dave Liquorice]

Yes there is that and as someone has already pointed out modern high density chip connections are not designed to be done by hand. Building something like a ZX81 with just ordinary components and 0.1 grid DIL chips is a different matter.

I'm wondering if I'll be able to construct the board I want to build to monitor the solar thermal/stove/heatstore/oil boiler/ch. One of the chips doesn't come in nice stubby finger friendly pinned DIP package, only in a surface mount version.

No many in the whole population of teachers but I'd expect the main technology teacher and the lab technician to be able to.

[Alan]

In message , Dave Liquorice wrote

You need a laser printer, some junk mail, a household clothes iron and some copper laminate board.

Some free software to layout the board

and the Youtube link

[Dave Liquorice]

build

*Producing* the board I'm not that concerned about it's actually constructing it once etched etc. My previous forays with surface mount rework have not been very succesful, ie not at all... B-(

Think the chips I need to mount are 0.05 pitch.

Thanks for that, looks useful. Are there any companies in the UK that offer a similar one off board making service?

[The Other Mike]

For surface mount the answer is flux, flux and even more flux and leaded solder for a predicable, proper and low temperature rapid melt. Most surface mount can be some with a decent soldering iron (50W, fine tip, temperature controlled) although using solder paste and reflowing an entire board in one go is relatively easy to do at home. - the results are near indistinguisable from commercially produced assemblies.

Not many that are worth bothering with.

The far east do them far cheaper and as a bonus you get a batch of boards to bugger up.

design, Eagle or KiCAD.

Some places will also do stencils for surface mount so you mount to solder paste and use a 20 quid oven to reflow the entire board.

Beta in Shannon Ireland are (were?) doing free metal solder paste stencils with their boards. Plastic ones also work but are not quite as good.

[John Rumm]

This guy makes it look easy:

[Jules Richardson]

Yes; I remember doing it to add a chip to a DVD player[1] that I had so it would work with all regions. It just needs a steady hand, and iron with a fine tip, and good eyesight (or a magnifier). Oh, and solder with useful quantities of lead in it.

[1] This was somewhere around 1997. That player's still in regular use at my parents' house, so it's done pretty well for itself.

cheers

Jules

[Mark]

Still got a good stash of leaded solder but I'm not sure my soldering skills would be up to it ;-)

[geoff]

In message , Mark writes

It's about time I bought a couple of dozen more reels - anyone got a suggestion for a good cheap supply?

I normally use CPC

[The Other Mike]

Depends how much you want to spend, I've a hot air blower from 'one-hung-low' in China that was about 50 quid but the soldering iron on it is crap and even for surface mount work the hot air blower is not that controllable, although that could be the operator.

I've a big 120W Weller with a half inch wide tip that is not safe near any PCB but is ideal for heavy cables and crimp terminals for which you don't have a crimper. Like you a few tiny Antex 15 and 25 watters from the 1970's that hardly ever get used, a couple of Weller Pyropens (butane fired) for heatshrink and odd soldering jobs on the car. A Weller desoldering station with a vacuum pump - 30 quid or something at an auction a few years back - new was about 500 quid, this one had been taken out the box, placed on a bench and looked like it had never even been turned on!

But my main 'workshop' irons are circa 1990 Weller 50W digital temperature controlled ones, one near perfect, the other battered bruised and with the base unit bodged with hot melt glue. For surface mount work they are ok, you can still get tips down to 0.4mm and up to about 3mm so one iron can do many jobs - low power irons simply don't do as good a job as a high power one.

The equivalent is probably this at 300 quid

'm sure something Chinese would work, but for how long is anyones guess - they can produce s**te and really good quality kit at a whim. Ebay for a secondhand Weller (not one with Magnastat tips) would be my recommendation.

If you are considering making a PCB for surface mount stuff then my advice is don't. Design and buy one with a solder mask as it makes life so much easier. It's cheaper to send the files to a sweatshop in the far east and have them produce them with FR4 than buying the Ferric Chloride and the cheapest crappiest bit of SRBP from Maplins.

If not then you can get prototype / breakout boards for fixing the surface mount chip onto, and then use pin headers or wire links to fix it to a conventional pcb or veroboard.

An example

[Dave Liquorice]

Ah the solder mask... that I can see making a huge difference to the "slide along the iron" soldering technique.

For one simple board?

Now that is useful, thanks. IIRC only one of the nine required chips is only available in SMD and I don't think there are many (any...) additional components so the adapter board may be all I need for the SMD. The other chips are bog standard DIL which I can do...

[The Other Mike]

Absolutely. But they don't just sell you one board, nor will they even make just one board. If you are prepared to wait three or four weeks for delivery then you can get ten boards 50mm square from China for, at current exchange rates, GBP 8.80. Yes, not even the tenner I said! so that is just 88 pence a piece.

That's not just an etched board, it can be double sided if you wish, with plated through holes, all come with a solder mask, and a silk screen if required and that price includes postage to the UK. Scale up to say 50mm x 100mm and its soars to a massive 19 quid...again for 10 boards.