Mark Morgan Lloyd wrote

mainframe switchmode PSUs, so with apologies to the list owner I'm probably in a position where I have to comment on this for safety reasons. My advice: don't.

Thanks for the warning. :)

any number of stories about people who've done something that they thought was safe which has gone on to cause damage or injury.

Same could be said for ridding a motorcycle (which I do often) or even crossing the road, but I get what you are saying.

Things like the output wire on low voltage PSUs are fair game for repair. You can get spare concentric connectors from RS or Maplin in the UK (Graeme- I thought you were abroad?)

I lived in the UK for 4 years, and moving back there in 2 months time.

unopenable by hand i.e. you /had/ to use screwdrivers etc.) then I'd suggest looking around for something like a C&G-accredited electronic technician course- which full-time would take years.

When I finished high school (many many years ago), it was a coin flip between studying pure programming or electrical engineering (light current) and hardware programming. I opted for the pure software programming, which has been my career path ever since. But I have always had the urge to start some part time studies to get an Electrical Engineering degree - those little colorful bits of electronics just fascinate the hell out of me (even 20+ years later). :-)

Thanks for the URL, I'll keep that handy in case I ever need some electronics repaired.

Henry Vermaak wrote

I'd advise against fiddling with switch mode PSUs.

See my other message to fpc-other mailing list. I have had a very long interest in electronics, I just never pursued it. Maybe it's time I scratch my itch. :)

I have two pieces of electronics that recently failed, and no easy way to replace them. One is a small AC power supply to a wireless access point. It uses a 5V power supply, which I just can't find anywhere here in South Africa - other that buying a whole new Wireless Access Point. :-( The other is a SATA-to-USB/Firewire400 adapter. I used it purely for the firewire port. I can see some bits turned dark/black on the pc board, and it smells like burn. I just have no clue how to repair it. Nobody in our area wants to touch it either. :-(

they turn out to be pretty crap (due to the cheapness).  Repair cables and connectors, perhaps even replace bulging capacitors, but apart from that, this is not hobby material!

I beg to differ. Case in point. My wife's uncle is a rep of some sorts for a large chemical supplier. His hobby is acoustics - those old valve amps and very weird looking speakers etc. Nothing related to his day-time job. Clearly valve amps are not as easy to come by these days, and neither is getting somebody to repair them. He started looking into that many many years back. He is now the local go-to guy in Gauteng, South Africa, to have your valve amps or speakers repaired or modified. :) He is on the verge of retiring, and guess what? He wants to officially make his hobby into a post-retirement career. :)

Programming is fun, but there are so many other things that are fun too. I'll probably enroll into some electronics course, because as I stated earlier - I have a huge interest in light current electronics, I just know nothing about it (but would love too).

Can't speak for RSA, but this is the reason people don't fix these things here:

http://uk.farnell.com/stontronics/ad-05100rbs2-1/adaptor-5vdc-1a-uk/dp/1279510?Ntt=127-9510

You misunderstood me, I'm talking about switch mode psu in particular. I'm an electronic engineer and I don't touch them. Amps are much easier to understand and much more fun to mess with.

Henry

Except that riding a motorcycle or crossing the road you have some idea of what the conditions are, and have spent a few decades honing your skills. Think of riding a motorbike through the Bushveld, and then finding yourself on black ice.

Think of the nastiest bit of software you've ever come across, spaghetti code with computed gotos (which I guess implies FORTRAN). When it comes to maintainability, that's roughly on a par with the best switchmode PSU, since you've got power and feedback moving in different directions through the same wound component. One of my colleagues spent a while designing them, and even he blanches at the idea of a repair.

SMPSUs are the last thing you want to tinker with, not the first. If you want to get into electronics fairly painlessly then start off with a BASIC Stamp or Arduino (I'm not aware of anything of that scale which will run FPC) and some project cookbooks. Also I believe that there are "maker" groups in most cities, although I'm not in touch with my local one.

Yell if you're in the Southeast.

Bering in mind that he is specifically PSU, and won't touch some types since they require proprietary components.

From elsewhere in the other thread, Lars said:

-----8<-----
To keep it on topic, there is programmable hardware available where you can change the hardware using a hardware programming language. Niklaus Wirth is interested in such technology. Instead of soldering in capacitors and resistors, you program in something that emulates a resistor or capacitor. This makes prototyping circuits much easier because instead of soldering, you program in the devices you would have otherwise soldered. The devices are called Field-programmable gate array's I think, and from what I remember Niklaus Wirth was programming a remote control helicopter with it, or maybe oberon, it's been so long that I cannot remember the details. Just trying to keep it a bit on topic.
----->8-----

There's two things here: the first is Digital Signal Processors (DSPs) where you program them to compute a series of equations in real time that implement one or more filters. Things like telecoms systems (including ADSL modems) are full of them.

Then there's FPGAs, although they're usually programmed in a specialised hardware description language. They aren't so much set up to emulate resistors etc. as to implement an application-specific CPU and associated logic, in some cases the hardware contains a CPU core (e.g. Michael Schnell's earlier

-----8<-----
IMHO, the MIPS port is interesting, too, as the NIOS CPU that is available as soft core for Altera FPGA uses a very similar instruction set and supposedly can be handled as a sub-arch.

There is a very active community for NIOS-Linux that now provides a quite decent MMU-enabled Linux port (including the necessary Distribution generating Make-based tool chain).

For quite some time I played with NIOS using a "NEEK" Dev-Kit from Altera. Nice stuff.
----->8-----

I can't remember for certain but I think it was Nicoud who was involved in the helicopters rather than Wirth. Nicoud is notable since one of his ETHZ projects was a portable assembler notation, I've wondered in the past whether this could be used for compiler implementation but I think it's probably less useful than some intermediate notation akin to p-code.

Agreed. The one thing I'd add though is that there's an increasing tendency for devices to be powered through a USB connector (even if they are not primarily USB peripherals) and unless the consumer remains vigilant it won't be long before mass-market appliances start insisting that they be mated with a PSU from their manufacturer.

Now granted that there's EU pressure to standardise this, but I'm sure that a manufacturer who argued that his PSUs contained extra functionality- like Apple's recent patent on backing up a password in the PSU- would be able to circumvent it.

Henry Vermaak wrote

Can't speak for RSA, but this is the reason people don't fix these things here:

Just one more reason to add to my list of why I am moving back to the UK. ;-) We get those "multi adaptors" that give 1.5, 3, 6, 9 or 12 volts, but just not 5v. :-(

A multi adapter set to 3V will give you about 5V lightly loaded, and set to 6V will give you about 5V on moderate load. The point about the ones that Henry cited is that they're mini switchmodes, they've got stable output and run cooler than "wall warts".

Graeme Geldenhuys wrote

Just one more reason to add to my list of why I am moving back to the UK. ;-) We get those "multi adaptors" that give 1.5, 3, 6, 9 or 12 volts, but just not 5v. :-(

Graeme,

For 5 V, I'd go for one the following:

http://www.jameco.com/webapp/wcs/stores/servlet/Product_10001_10001_380621_-1 5.0 V, 20 W
$19.95

http://www.jameco.com/webapp/wcs/stores/servlet/Product_10001_10001_2123266_-1 5.0 V, 30 W
$24.95

Make sure you get the same of greater wattage as that of your old adapter.

One more thing: Don't know what kind of connector you will use/need, in the worst case, you will have to nip off the connector from the old adapter and solder it to the new one (paying attention to polarities, of course).

While I do know that Jameco does do international shipments, I don't know how it all works out for SA --it could be that postal charges or customs duties etc might turn out to be prohibitive.

In that case, I'd Google for the product codes to see if they are available.

HTH,

Adem

Using the 3V setting doesn't power up my Wireless AP. Using the 6V setting does, but it ran very hot, so I opted to stop using it until I could find a 5V adapter.

2012/1/30 Adem :

Make sure you get the same of greater wattage as that of your old adapter.

Thanks for the tip and the URLs. Seeing that I'm moving back to the UK, I'll rather order one after I relocated. Postage and Important duties in RSA normally more than double the price of any overseas order. :-(

One more thing: Don't know what kind of connector you will use/need, in the worst case, you will have to nip off the connector from the old adapter and

Yeah, that shouldn't be a problem. I have some soldering skills. ;)

this is when one might tack a resistor in the line to reduce the voltage reaching the device... that resistor might become pretty hot, too, though... especially sinking one volt at whatever amperage is being pumped...

Or one or more ordinary silicon diodes, wired to conduct, each of which will drop about 0.7V largely independent of current. However if the supply itself is unregulated it will still fluctuate wildly when the load changes.

Actually, for fixing things, you could check the ifixit.com site, they have all sorts of manuals on repairing things. Though, I've never seen anything like firewire to anything else adapters. Although, I do like building things, so I plan to make some adapters of my own, though usb to firewire wasn't one of them. :) Guess it wouldn't hurt to experiment a bit huh?
heh.

Depending on what kind of 5-volt supply you want, parallax has a few in their store, (the maker of the basic stamp and propeller boards) and one of those might do the trick for you, though since they are designed for powering small circuit boards, you may need to splice a different connector on to it or something.
I don't know if this will work for you or not, But, here's the 5-volt supply they have.
http://www.parallax.com/StoreSearchResults/tabid/768/txtSearch/power/ List/0/SortField/4/catpageindex/2/ProductID/242/Default.aspx

They have 7.5 and 12 volt supplies too, but that's the only 5-volt item in the store, though I thought they had two of them, I can't locate the other one, though it's just as likely it was the 7.5 supplies they had two of, and I'm just confused. :)