One of the 'things' I was going to ask the students

Just a thought...

You might have noticed I used a Solar Garden light in the session on QRM/EMC, well it occurred to me to check the design in the UK. Slightly different but essentially the same simple circuit. Which oscillates around 1 MHz!

What? Yes it does. The question I was going to ask is this; "How do you get a L.E.D. to light when you only have a 1.2 Volt battery?"

When you did the section on transistors did someone tell you about 'inductive loads'? Or why you need a 'protection diode' across a relay? The same applies to a r.f. circuit with a coil in the collector circuit. Tuned or not it will swing above the supply rail voltage to double the collector voltage rating. So if you connect a transistor to a 12 Volt rail, remember the Vce rating must be 24 Volts or greater.

Remembering that a coil stores the energy in the magnetic field. So when you turn off the current the coil tries to maintain the field. Generating a 'back emf' that in some cases can be kiloVolts! Just arrange a relay as a 'buzzer' with the contacts making and breaking the circuit. Don't touch it! Depending upon the coil inductance the voltage can reach a very high voltage.

So the simple circuit these days is a single integrated circuit. A coil, the solar panel and the L.E.D. With the i.c. doing the charging and switching on the L.E.D.

[I just a fruitless search for a circuit that I know I downloaded months ago! Now thanks to Bert's blog I have one. https://bertsblogs.com/garden-solar-light-circuits/]

He explains the circuit as well. As he and I was going to here is the simple fact. The LED is a 'super-bright' white LED which needs well above the typical 1.8 Volts to turn on. L.E.D.s are much better these days from the 60s and 70s versions which were always red and quite dim in comparison to the filament bulbs/globes of the day.

The one thing I noticed as a difference between the ones I had bought in South Africa and the ones in the UK, the batteries are NiCd in SA (cheap). The ones in the UK are Nimh. Nickel-cadmium versus Nickel metal hydride. Small pricing difference but on thousands of models makes a big difference.

So are they going to interfere with your h.f. reception? Probably not unless you have a few hundred in the garden.

They don't last long. Water ingress usually rusts the connections and screws. Treating the plastic with sealant is just not worth it. Replacing the NiCd battery with a shop bought Nimh helps. But then sealing with marine silicone will keep maybe a few years longer.

73 John ZS6WL
 

This weekend has been informative, instructive and wet!

A relatively peaceful weekend from Friday but with another 'incident' in Windows XP.

My friend Roy, came to me with a "Scareware Virus" called MS Removal Tool. (My first thought was - what a good idea - maybe Ubuntu...) But no, this turned into a 'major mission' to remove and recover control of his PC. It would not allow him to use any of the standard anti-virus measures nor run any diagnostic software like 'Task Manager'.

How did he get it?

Very simple, he went to a web site that had been 'click-jacked' and without him knowing, the 'virus' was installed on his PC. He was using Internet Explorer and he has Microsoft's Security Essentials. Unfortunately both are side-tracked and bypassed by this rogue software.

This is the same category of malware that disrupted another client's PC recently. There it was called 'AntiVir'. It would not allow the user to remove the virus without going into 'safe mode'. This is not the easiest of methods for an inexperienced user who may have never seen 'Press F8 to enter safe mode.'

[Since this time, a few more of my clients have come to me to 'remove' the 'ScareWare' worms and virri.]

Live Security Platinum is the latest 'scareware' worm to hit here in SA [2012]

This worm/trojan puts up a 'front' and shows you a scanning of your hard disk with a load of virii etc. While loading its 'hooks' into your system to 'own' (pwn) it.

Live Security Platinum – ThreatExpert submission [2012-07]

http://www.threatexpert.com/report.aspx?md5=e5602b9c25da9a41cf555b8e35af9742

This submission is dated 11th July 2012. So it is quite 'up to date'.

New and Improved Worms and Virii are being made right now.

'Scareware' does more 'damage' to user confidence and productivity than previous types. It also carries with it a 'payload' of worms and virii. Most are detectable but some are variations that have not yet been 'captured' in the wild.

[The 'variation on a theme' seems to be prevalent as well. Meaning that old and workable virusii can be 'recycled' into new and even more upsetting variations. In the 'process' they are disguised so that the latest anti-virus products do not recognise them.]

“Data Recovery” - what a joke!

This was to be expected. As more and more 'black hats' discover the usefulness of 'bots' and worms that really can do 'damage', they are getting to release these on the day of your anti-virus 'update'. Otherwise known as 'zero day exploits'.

DO UPDATE YOUR Microsoft Security Essentials when you can.

DO NOT HAVE TWO OR MORE Anti-Virus products installed on your PC. The Microsoft Security Essentials, formerly called 'Windows Defender' works. Don't accept Mcafee as part of ADOBE's update. You will have to de-install it later if you do.

Sent at 8:45 AM on Thursday

John: I see my M$ sec essentials has gone from 411 to 601 in a few days. Your contribution I am sure has helped 'update' it...

This is on my 'no 2' PC not my 'no 1' PC. This one was updated yesterday. And this morning. Thanks Nick!

Now you should start using FireFox and or Chrome. Also update Internet Exploder to the latest possible version.

Sent at 9:20 AM on Thursday

John: I think you should run 'Windows Update' as well now. The IE8 version has just

're-installed' the activeX control for IE8 and Windows Update. I think that the previous version has been 'compromised'.

Yes! Install it.

[Alternate 'Data Recovery' removal instructions:

1. First of all, you need to unhide the files and folders. Select Run... from the Start Menu or just hit the key combination CTRL+R on your keyboard. In the Open: field, enter cmd and hit Enter or click OK.

At the command prompt, enter attrib -h /s /d and hit Enter. Now, you should see all your files and folders. NOTE: you may have to repeat this step because the malware may hide your files again. --- This does work. But does not remove all the 'hooks'. ]

'By the rivers of Babylon' – To 'remove' Babylon...

Open a dos shell, or execute "RegEdit" through the launch menu.

Find the key: [taint there! WinXP]

HKEY_LOCAL_MACHINE

...

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Internet Explorer\About URLs\Tabs

and change the entry that points to babylon search, to the one you desire (be it google, bing, or whatever)."

Alternate removal: run

C:\Program Files\Babylon\Babylon-Pro\Utils\uninstbb.exe

Microsoft Security Advisory (2719615)

Vulnerability in Microsoft XML Core Services Could Allow Remote Code Execution

Published: Tuesday, June 12, 2012

http://technet.microsoft.com/en-us/security/advisory/2719615

[reply to email from client]

Hi Steven

Thank you for the nice compliments. I have never liked making money from the misery of others. The sort of virii and worms we have today have a far more devastating impact on the running of a business than last century.

Your 'incident' has actually taught me a new way of counteracting the 'scareware'. I can now boot the infested PC with a memory stick or CD. Then copy the Microsoft 'search and destroy' software to the hard disk. Also at that time, I can remove any obvious infestation. Files that are placed as a 'payload' by the scareware. Then rebooting into safe mode with networking, I run the msert program. The program can be deleted now as it only works for 10 days. Requiring an update at that time. If you had let it alone, the PC would have 'announced' itself on the Internet as a PC that can be 'owned' and run as part of the extensive networks of 'Bots'. These 'Botnets' are used to deny access to major servers and spam vast numbers of recipients. All operating without your knowledge and participation.

Little wonder that 'organised crime' have found this more profitable than drugs!

All of the best for the future.

Best regards
John Brock

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Tools of the trade

Various web sites offer software 'tools' that will 'get rid of' this malware. One is:

Spyware doctor

http://www.spyware-experts.com/ms-removal-tool/

another is:

MalwareBytes Anti-malware

http://www.malwarebytes.org/

There are a lot of others, too numerous to go into here. Some give manual methods for removal. But state that this will be limited in effectiveness as the 'virus' changes the file names and registry entries on a daily basis. This also confirms the conclusion that I had come to, that no single anti-malware product is going to be 100% effective.

What did I use?

I used the latest 'Hiren's Boot CD' to boot his PC into mini Windows XP. [You can download it from: http://www.hirensbootcd.org/download/] Then I ran three of the malware removal tools on that CD. All ran and said that they had completed a 'removal' or 'clean'. We then rebooted into his Windows XP and ran 'msert'.

 

That is Microsoft's Safety Scanner tool that you can download from:

http://www.microsoft.com/security/scanner/en-za/default.aspx

This 'tool' runs, scans and removes with an up to date malware table. It 'expires' in 10 days so that you will always need to download the latest version.

When we rebooted his PC into Windows, we found no trace of the virus. Thank goodness.