Success! Made parrot_knight's computer boot to windows. Remember chkdsk /r, if necessary more than once.

Google Wave could turn out to be very interesting. Email, blog, chat, shared documents, and other stuff, all in one pair of trousers. I want to play with it!

I am trying to fix a computer that won't start up. It begins to boot to Win XP, then quits and restarts, forever. The recovery disc that came with the machine does not permit any sort of recovery other than restoring the hard disk to how it was when new - in theory. There is no means to break out and run chkdsk, for example.

The Win 7 RC beta disc, for which you can download an iso image from Microsoft, is bootable, and has an option to repair a windows installation, as an alternative to proceding with a new installation. It has an automated repair option that can fix some faults, such as a corrupted mbr, and also has a command prompt option, from which it is possible to run chkdsk.

There is no reason to think that this will stop working even when the beta times out.

... brighter than a thousand suns - or at least, as bright as a 400W metal halide lamp.

For about the last 3 weeks, as well as other ongoing tasks, I have been working long hours on designing parts of the first prototype of a luminaire that is intended to be as bright as a 400W metal halide lamp, though the one model we tested only consumed 150W of electricity. Photometry, to be carried out by the prospective end user, will discover if the intended light output is reached, but it is very likely, because the overall designers of the luminaire have done the maths, and consulted optical designers.

It was too bright to look at, even wearing sunglasses.

There are seven LED printed circuits, each with two series strings of 12 white LEDs, independently dimmable. The LED strip is made on a type of printed circuit consisting of a thick aluminium substrate (to carry away the heat from the LEDs), with a very thin insulating layer, of a material chosen to be thermally conductive, and with the copper tracks etched on top of that. There is only one layer of connections, which makes the design difficult, but this composite material is needed to remove the heat from the LEDs. They are specified to lose only 20% of their light output over 60,000 hours if run at the maximum specified temperature, but above that level, the reliability declines rapidly.

Energy savings alone might not render this product cost effective, but when the close to zero maintenance costs are included, it should be very good in its intended use (initially fuel station canopies). In real use, the lighting is likely to last until the building is subject to major maintenance or remodeling.

This was an interesting project to work on, but had a difficult deadline, because the requirement to deliver all the electronics for three units was brought forward by 6 weeks. I predicted and avoided one electrical problem associated with the unusual PCB material for the LED strips, but had to retrofit extra parts to correct for another one (very high capacitance between LED and substrate). It was a first prototype.

The (switchmode) electronics to dim and control the current in the LED strips is on the same PCB as the LEDs, but is very constrained because most of the area is covered with reflectors, so that parts more than 3mm thick can only be placed in an 8mm strip at one end of the long narrow pcb. It is for this reason that the capacitance between the LEDs and the substrate was an issue. Had it been possible to fit the inductors in the ideal place, the capacitance would have been irrelevant.

The control and comms electronics is on a 21mm wide pcb that plugs into all the LED strips and carries power and control signals from the processor to control brightness, measure temperature, and so on. That contains, among other things, a memory chip carrier 19mm wide, so I had to design it with four layers. Even the on-board switchmode regulator worked cleanly, which is good because there was no time to make a revised control pcb.

It is done for now, finished yesterday evening, and I will not know if the project is to proceed for about a month. Now to catch up with the major backlog of other tasks. If anyone is expecting any kind of response from me, and I don't catch up soon, please remind me, because I have not been noting everything while concentrating on this project.

Wolfram Alpha can do real maths, even things I struggle to remember from (cough) years ago at university. I could not figure out this one for myself, when trying for an analytical solution to the loss in a ferrite core used in a critical conduction power factor corrector.

integral sin^2.6 x

But Wolfram can. I think I may try again to find the analytical answer I want, and if energy and my copious free time permit, eventually embody it in some design software I can use to optimise the design of a certain specialised variety of power supply.

System rescue cd is stunningly useful. It may allow me to solve the problem with parrot_knight's laptop. YOu can copy a partition from one disk to another, resize partitions without losing data, reset a lost windows password, do some types of disc repair... and so on. I just used it to copy the bootable partition from a 160G drive to a new 500G drive for my laptop. I made the new partition much larger, of course ;-) It was not perfect, I had to fix the master boot record. Then it worked  fine. Oddly, the win7 release candidate disc fixed the boot record of a vista partition in seconds.

Some more free hard disk backup, clone, and restore software.

A way to set up a USB memory to be bootable.

We saw it at last, and did enjoy it. Exactly why about a billion pounds worth of starship was so readily being driven by trainees is not so obvious, but if you blink at that sort of question it really was fun.

One day I wuld like to watch a movie with all the special effects and stuff that the movie makers art does so well, but also a sound story line.

Look at that! Wow, I haven't ever seen a pig fly so fast before.

Copied from gervase_fen. and reprinted here in entirety:

If you're on Twitter, set your location to Tehran & your time zone to GMT +3.30. Iranian security forces are hunting for bloggers using location/timezone searches. The more people at this location, the more of a logjam it creates for forces trying to shut down Iranians' access to the internet. Cut & paste & pass it on.

But I have been fairly non-responsive because I have a lot of work to finish in a short time. After that there will probably be less than the ideal amount of work, I imagine. So it goes for a freelance.

took yesterday evening off, we visited friends in Stony Stratford and, as always when we go there, had a great meal and ate ourselves to a standstill. A. is a genius in the kitchen, and S. has just been made redundant, so if anyone knows of an opening for a really good network engineer...

Now to return to my work - one of the PCB designs for the LED luminaire. Then I need to order parts for a prototype, and write a report, for another customer...

Whoever I voted for, the government got in and some political parties nominated some of their members to place their snouts in the trough. Big surprise.

At the polling station, which was a school, there were notices on the wall. One of them referred to computers, and another to computer's.

It is not surprising, with that example, that those educated more recently are unsure about what to do with apostrophes. I have long passed the point of being amused by apostrophe's used in pluroal's all the while, and now it just irritates me to see a hage engraved "CD's" sign over s supermarket aisle. <sigh>

My Vista laptop will no longer access other computers n the same workgroup. I have checked everything that seemed obvious to me, including:

-Netbios is enabled over tcpip
-The problem continues when the firewall is switched off
-Can ping other computers by IP address, but not by name
-net view gives an error saying that the list of workgroup comuters is unavailable
-Internet access works fine
-All the appropriate options are switched on in the network and sharing centre
-All other (non vista) computers share files and directories correctly.

The vista machine:
- can ping internet sites by name
- has an IP address in the right range
- has the computer browser service running
- gives an error message when I try to access already-mapped network drives

It did work up to about 2 weeks ago, but either I ran a windows update, or changed something else minor that did not seem contentious, and it stopped working. I haven't got any restore points earlier than a couple of days, so no help there.

Since then, in an attempt to fix the problem, I ran a registry fixer on it. over 800 errors were reported and fixed, though some were trivial. The same procedure resolved a master browser problem that prevented a Win XP machine accessing the workgroup, for which no other attempted solution had been effective. However, in that case it could not access even it own shared directories via network places, until I stopped the computer browser service, and it was iffy after that. The vista computer lists its own network shares, but none from anywhere else. The vista computer indicates its own network shares, but none from anywhere else.

I ran SP2, and whatever that may have fixed, it did not fix the network access problem.

Has anyone got any ideas?

Snaffled from nakeisha

You Are a Dreaming Soul

Your vivid imagination takes you away from this world So much so that you tend to live in your head most of the time. You have great dreams and ambitions that could be the envy of all... But for you, following through with your dreams is a bit difficult. You are charming, endearing, and people tend to love you. Forgiving and tolerant, you see the world through rose colored glasses. Underneath it all, you are brimming with passion that you keep hidden. Always hopeful, you tend to expect positive outcomes in your life. Souls you are most compatible with: Newborn Soul, Prophet Soul, and Traveler Soul

I spent most of my day working as a counsultant for a company with offices in Milton Keynes, at their offices and at one of their suppliers. I discovered a number of problems on the electronics they were being supplied with, much of it at the pre-production sample stage. Bullet dodged, from their point of view.

( Read more... )

After being stuck for some time on the problem of stabilising the control loop for the battery charger, I may now have found a workable answer. Yay!

Though it was tricky to do so, I modeled it in a simulator, and the graphs of phase and gain were so much better than hand drawn sketches that I was able to find an answer.

Now for some belated sleep, before the rest of the weeks work, for which I would have preferred four days, to allow for purchasing the necessary parts to upgrade a prototype power supply from 110W to 200W.

Since the middle of last week, the main task I have been working on is to stabilise the voltage control loop of a switched mode battery charger. The design is slightly more complex than some, because the output voltage can be both above and below the input - so it uses a sepic converter. Not a big deal, but slightly more difficult to control. The control loop oscillates over a range of 0.2Hz to 500Hz, depending on the components fitted to attempt to stabilise the loop. The one thing it won't do is work in a stable and accurate manner.

( Read more... )