Monday, January 30, 2012

Twittering Morse Key - Tworsekey

I'm certainly not the first to theorize that if there is a greater than zero probability of something happening then you'll find it happening on the Internet. So it was when I stumbled across this home brew creation of Martin Kaltenbrunner. Martin has created a Morse code key that decodes whatever you hammer out and sends it to a Twitter account, thus neatly bridging more than 160 years of history while ranking fairly high on the, "But why?" scale. I have no idea why Martin created the Tworsekey but you have to admit that it looks great and I wouldn't mind having one siting on my desk.

Sunday, January 29, 2012

Winter Field Day and a Magnetic Loop Antenna

Last Field Day I spent a fair bit of time taking photographs and video which made for an entertaining record of the event when uploaded to YouTube. This time I was determined to do something more in tune with the Field Day theme and actually get my hands dirty ... or possibly burnt, cut or crushed (Physical coordination not being my strong point). Fortunately I only sustained one small scrape in the course of constructing a magnetic loop antenna for the 30 - 10 meter bands (A frequency range can be measured in meters since wavelength is directly proportional to frequency, a frequency of 7.49 million cycles per second has a wavelength of 40 meters at the speed of light). I had finished the antenna construction Saturday evening but the 20M band had fallen silent as ionospheric conditions favored the longer wavelength bands like 40M ... which the antenna didn't cover.

On Sunday morning the 20M band opened up again and I was able to make contacts all over the US using 10 - 25W. If you stop to think how far the light from a 25W light-bulb can reach it puts the fact that I could talk all over the US, using the same amount of power, into perspective!
My loop antenna is a simple resonant circuit: Consisting of a loop of copper connected to a variable capacitor. A smaller matching loop inductively links the transceiver to the larger copper loop so the radio see the right load.

The devil is in the details of course but I'll save a discussion of theory and construction for another post. There was a fair amount of interest in the loop as other folk also live in similar antenna restricted neighborhoods and are prohibited from putting up large antennas for the HF bands. Another ham brought out a very fine commercial loop antenna with a flexible loop that could be packed into a netbook sized bag. Such an antenna could be just the thing for trekking with a radio and operating in the great outdoors.
Seems I didn't learn my lesson with cheap coax ... The short piece that connects the wire matching loop to the longer cable run was a piece of RadioShack brand with a PL-259 connector conveniently attached. As I started started to transmit I noticed the SWR (Reflected power ratio) start to rise the longer I transmitted. As soon as I stopped for a moment it quickly dropped so I knew that whatever was getting upset had to have a fairly small thermal mass ... it wasn't the tuning capacitor for sure! I'll have to swap out the short piece of coax for a SO-239 socket and run my good coax directly to the antenna. While I was testing and making a few field day contacts I kept the power level low which kept the SWR under control.

Tonya added her baked creations to the Field Day menu and I suspect we may have beaten last years time in consuming everything apart from one slice of apple pie which lasted until Sunday morning. We were extremely well fed with delicious food thanks to many contributions with special thanks to Mike N5TGL and his wife who hosted the event and tolerated our impromptu lectures and animated discussions of ham radio miscellany for the two days of Winter Field Day.
The Society for the Preservation of Amateur Radio is the organizing body that schedules this event for the last full weekend each January. The object of the event is familiar to most Amateur Radio operators: set up emergency-style communications and make as many contacts as possible during the 24 hour period. The rules encourage as many contacts on as many bands and modes as possible, because during a real emergency, the most important factor is the ability to communicate, regardless of band, mode or distance.

Thursday, January 26, 2012

ARRL President Kay Craigie, N3KN presents an insightful and inspiring talk about Amateur Radio

Lately I have been giving a lot of thought to the notion that, as a amateur radio operator, I should be engaged in this or that activity ... should volunteer for something ... should be building equipment ... should be operating more ... well, you get the picture. I enjoyed the following video because it highlighted the variety of experiences in amateur radio and how each has value to the community in its own way.

If you talk to any group of ham radio folk (or read through a ham radio publication) you'll always run the risk of feeling that somehow you're just not doing enough stuff and that you're not holding up your end of the deal. The FCC made allowances for you to operate on several bands of frequencies which are set aside for amateur radio use ... you really should be using them right?
The answer to that ... as far as I now think ... is yes, and also maybe. To be perfectly honest I do enjoy getting on the air from time to time and making contacts, usually digital as I don't seem to have an ear for picking out SSB voices from the noise. However ... there are other things like vintage vacuum tube equipment, experimenting and the history of ham radio technology that I enjoy more.
I came to realize that, much like genetic diversity, a ham radio club that has members interested in a wide range of things could potentially be more robust and offer a greater service to the community and its members. There is one critically important caveat here however and it has been the downfall of several special interest clubs in the past. In order for a club with members having diverse interests to survive and thrive there must be a significant amount of tolerance shown by each and every member. We are both united by a common interested and made unique and interesting by the variety of ways that common interest is manifest.
If you don't operate QRP then stop a moment and talk to someone who does, if you only operate CW then chat to someone who operates digital modes or phone. Different disciplines can always benefit from a little cross traffic and you may be amazed at what you learn!

Tuesday, January 24, 2012

Pop's Shed and the Kingsley Radio AR7

After my grandfather passed away I spent a lot of time recalling the good times I had spent scrounging around his CB shack and hanging out with Pop "down the shed". If you've spent time around old motorbikes, retired lawn mower engines, vacuum tube electronics and inches of dust you know what the shed smelt like and probably have a pretty good idea what it looked like as well.  I used to be able to send Mum into fits by embedding a combination of oil, grease, dust and grinding compound into the knees and sleeves of my good clothes after spending the day "over south" (South Geelong)

Even now I can still walk into any old auto mechanics and the smell brings back dozens of memories as clear as day ... but one memory in particular had been bugging me for a while now. On several occasions I had used a magnificent rack mounted shortwave receiver that had been hooked to a long-wire antenna between the shed and the house. It had several plug in coils housed in bright metal boxes, one for each band as well as a unique tuning dial that had windows around the circumference with numbers that updated as the dial was turned.

National HRO right? ... Nope, its an Australian clone!
For the longest time I was thinking what you are probably thinking now, I had been using a National HRO receiver right? Well, you'd be wrong ... just as I had been for years! When I eventually asked my uncle about the receiver (I waited a long time as I feared it had been thrown out & honestly didn't want to know if it had) he said, "The AR7?" ... "Yes, its here in the garage covered in dust". He went on to say that I could have the receiver if I could figure out some way to ship it ... not a slight problem given the receiver, power supply and speaker are over 120 lbs!

Knowing now that I had been using a completely different receiver I set to work and found out what I could about this National HRO clone ...

From :

The AR7 was produced during WW2 by Kingsley Radio of Melbourne for the R.A.A.F. These receivers were used in ground stations for long range communication over fixed circuits as well as for receiving signals from aircraft.

The AR7 was based largely on the National (USA) HRO model, a fact that did not go unnoticed by National. This was the subject of litigation during the war years. Over 3000 of these receivers were produced and for their time, produced excellent performance.

These sets were very popular with radio amateurs after the war and unfortunately subject to many modifications. The Wireless Institute of Australia station, VK2WI at Dural New South Wales was equipped with modifed AR7's for many years. I seem to remember that very local operators could block the receivers completely, resulting in hurried phone calls!

An unmodified AR7 is a rare beast. The Department of Civil Aviation used these sets for many years in a highly modified form, requiring a new front panel. Refinements included squelch and crystal locked coil boxes.

From :

The AR7 is a communications receiver covering LF and HF bands. It was made in Australia during 1940 and bears an extremely close resemblance to the National HRO receiver. The receiver has a tuning range from 138 kcs to 25 mcs, with a gap of 45 kcs either side of the 455 kcs IF amplifier. The internal design is a single conversion superheterodyne receiver with 2 RF stages, 2 IF stages, a BFO and an "S" meter amplifier. The sensitivity is quoted as 1 microvolt. The front panel is stainless steel and  it is a very distinctive looking receiver.

It is a good performer, sensitive, has a nice feel, is easy to tune, but hard to find the correct frequency, by reading the frequency from the dial number and coil box graph. It really needs a crystal calibrator.  I use it for the weekly W.I.A. (Wireless Institute of Australia) broadcast, so it gets turned on once a week, and is so stable, than I don't have to retune. It is very clear for AM but a bit fiddly for SSB.

The controls are: RF gain, BFO note, AVC/BFO switch, Adjust "S" meter, Tone, Tuning, Noise limiter, Selectivity, Crystal IN/OUT switch, Crystal Phasing, Audio gain. The Audio gain control has an OFF position which removes the HT so that the coil boxes can be changed.

It has two 6U7G RF stages, a 6K8G mixer, two 6U7G  IF stages at 455 kcs,  a 6G8G detector/AVC/audio preamplifier, and a 6V6G audio output amplifier. It has a 6C8G twin triode as a BFO and "S" meter amplifier. It also has a crystal filter. The IF alignment should be done very carefully, as any misalignment will reduce the effectiveness of the filter. It is best done with a sweep generator. The 6 volt valve heaters are connected in series, for 12 volt operation.

The external power supply and speaker, are usually mounted in a short 19" rack, the AR7 at the bottom, the speaker in the middle, and the power supply at the top. The complete unit weighs about 118 pounds. The power supply was switchable between 12v and 240v.

The receiver was used as a ground monitoring receiver for aircraft. It was extremely stable. The model shown has an R.A.A.F. nameplate, and serial number 1786. The manual I have is a D.C.A. (Department of Civil Aviation) version and is a 1947 issue.

It has 5 plug in coil boxes. The coil boxes are: band A 140-405 kcs, band B 490-1430 kcs, band C 1.420-4.3 mcs, band D 4.25-12.5 mcs, band E 12.5-25 mcs. The Army version had an extra coil box covering 50-150 kcs. The large dial is a 20:1 reduction drive and has graduations from 0 to 500. It acts like a flywheel when tuning across the band, and has an effective scale length of 12 feet. The dial shaft goes into a right angle reduction gearbox and has 2 output shafts that drive 2 dual gang capacitors. The graph on the front of each coil box is used to covert the dial reading to frequency.

Monday, January 23, 2012

Crystal oscillators and radio transmitters

Since the very early days of ham radio, crystals have been used to provide stable and precise source of transmitter frequency control. In addition, they have also been used in filter circuits to control bandwidth and prevent the reception of unwanted signals.

A quartz crystal from my collection. It is a FT-243 style holder, suitable for use in a vacuum tube transmitter.
Early transmitters used variable capacitors and inductors to create a self resonant tuned circuit. One drawback to this simple design is that it could change frequency depending on temperature, humidity, supply voltage or the proximity of conductive objects (Including the operator!). Shielding and temperature compensated components helped to reduce frequency drift but it was still common practice to follow the transmit frequency of another operator as both your receiver and his transmitter drifted.

The QRP sized AMECO AC-1. Using a single 6V6GT as oscillator and output tube.
From 1951 holders of the Novice class license were only permitted to use crystal controlled transmitters limited to 75 Watts. They were also further restricted to a small segment (3.700 - 3.750 Mc) in the 80M band. This had the side effect of popularizing simple crystal controlled transmitters using either a single vacuum tube as both oscillator and output amplifier or transmitters using one tube for the master oscillator circuit and one for the power amplifier, also known as MOPA (Master Oscillator, Power Amplifier).

The Heathkit AT-1 transmitter. One oscillator tube 6AG7 and one power amplifier tube 6L6.
In either case a crystal was required for every frequency you wanted to transmit on and few new hams could afford more than a couple of crystals for their transmitter. Often you would call CQ and listen up and down the band for someone replying to your call as the other operator would not necessarily have the same frequency crystal as yours.

But how do crystals work?

From Wikipedia:

A crystal oscillator is an electronic oscillator circuit that uses the mechanical resonance of a vibrating crystal of piezoelectric material to create an electrical signal with a very precise frequency. This frequency is commonly used to keep track of time (as in quartz wristwatches), to provide a stable clock signal for digital integrated circuits, and to stabilize frequencies for radio transmitters and receivers. The most common type of piezoelectric resonator used is the quartz crystal, so oscillator circuits designed around them became known as "crystal oscillators."

Quartz crystals are manufactured for frequencies from a few tens of kilohertz to tens of megahertz. More than two billion (2×109) crystals are manufactured annually. Most are used for consumer devices such as wristwatches, clocks, radios, computers, and cellphones. Quartz crystals are also found inside test and measurement equipment, such as counters, signal generators, and oscilloscopes.

An electric current causes the quartz crystal to deform.

When a crystal of quartz is properly cut and mounted, it can be made to distort an electric field by applying a voltage to an electrode near or on the crystal. This property is known as piezoelectricity. When the field is removed, the quartz will generate an electric field as it returns to its previous shape, and this can generate a voltage. The result is that a quartz crystal behaves like a circuit composed of an inductor, capacitor and resistor, with a precise resonant frequency.

Deforming the quartz crystal causes an electric current to flow

Quartz has the further advantage that its elastic constants and its size change in such a way that the frequency dependence on temperature can be very low. The specific characteristics will depend on the mode of vibration and the angle at which the quartz is cut (relative to its crystallographic axes).[8] Therefore, the resonant frequency of the plate, which depends on its size, will not change much, either. This means that a quartz clock, filter or oscillator will remain accurate. For critical applications the quartz oscillator is mounted in a temperature-controlled container, called a crystal oven, and can also be mounted on shock absorbers to prevent perturbation by external mechanical vibrations.

Wednesday, January 18, 2012

Remarkable relay computer - The TIM-8

Computers don't really make very impressive noises now-days. Hard drives whir and cooling fans exhale white noise, you might detect the quite chatter of disk access or the groan of a failing fan but that is about it.

Rewind a few tens of years and computers used to make really impressive noises that matched their impressive size. A virtual symphony of noise told you that things were really happening in there, things that could probably take a finger off it you happened to stick it in the wrong place!

1955 computer engineer. Popular Mechanics in 1949 confidently declared: "Computers of the future may weigh no more than 1.5 tons"
Every now and then someone gets the urge to recreate a piece of history, a computer that makes the right kind of noises along with other essential prerequisites like blinkenlights and a paper tape reader.

The latest creation I have seen was built by Rory Mangles and christened TIM-8. It is the 8th in a series of increasingly complex and refined builds the last of which qualifies as a complete computer with input/output and processing abilities.

The TIM-8 8-bit relay computer using on 152 relays.
Check out the YouTube video below for an example of TIM-8 executing a program from papertape.

Tuesday, January 17, 2012

Hellschreiber and microprocessors - Bridging more than 80 years

ZL1HIT (Bryan Rentoul) has bridged a gap of more than 80 years by combining the text transmission system developed by Rudolf Hell in the late 1920's with current microprocessor technology.
A sample of received Hellschreiber test from Bryan's beacon
Hellschreiber sends a line of text as a series of vertical columns. Each column is broken down vertically into a series of pixels, normally using a 7 by 7 pixel grid to represent characters. The data for a line is then sent as a series of on-off signals to the receiver, using a variety of formats depending on the medium, but normally at a rate of 112.5 baud.

This process was historically accomplished with mechanical equipment but there are very few examples of this equipment still in operation and it is now sent and received by computer. Hellschreiber is very tolerant of noise and interference and requires only simple transmitters and receivers to work effectively.

German Hellschreiber unit in operation
With a microprocessor generating the digital on-off signals a simple crystal oscillator transmitter can be used to form a beacon station, one that transmits a call sign and perhaps some other information over and over. Changing the transmitted message is as simple as reprogramming the microprocessor or having it respond to a connected input, for Eg. A thermometer, light sensor, switch, etc.

Receiving the signal and decoding requires a radio receiver capable of CW reception and a computer running any of several free software packages like FLdigi or Digital Master 780.

The ZL1HIT beacon using a PIC microprocessor and a simple crystal oscillator transmitter.
For more information and the PIC microprocessor source code please visit the web page of Bryan Rentoul here : ZL1HIT Hellschreiber / PIC Beacon

Monday, January 16, 2012

Homebrew Hero - Homemade NBTV video recording system in 1974

What do you do in 1974 if you are 20 years old and want to send video to other Amateur Radio operators?

An off-the-shelf home-video camera was the equivalent of $8000 USD (if you could find one) and the circuitry required to transform the high bandwidth signal into one that could be transmitted on AM would have been prohibitively complex.

Believe it or not the only solution was to build your own narrow band video camera! These creations followed on from narrow band television work done in the 1930's and took advantage of advances in materials and solid state technology.

The camera used by VK3AML (Chris Long) in the video below was a Flying Spot Scanner camera which required a completely darkened room and used a spot of light that scanned the scene. The reflected light was picked up by a photomultiplier tube and recorded as a frequency modulated audio tone on tape or broadcast via radio.

We're fortunate to have some of the original video preserved from 1974 since the audio and video signals had been recorded onto open-reel tape.

The 30 line television system developed by John Logie Baird in the 1930s allowed home experimenters to build their own equipment, a practice which still exists today through the Narrow-bandwidth Television Association. Relatively few narrow-band TV signals are transmitted nowadays so most amateur radio operators are unaware of this special interest group.

The video below shows some of the actives and projects that members of the Narrow Band Television Association have been involved in and gives some historical background on this interesting field.

Chas (WA1JFD) from the Antique Radio forums mentions that at approximately the same time other amateur radio operators such as Donald Mara (WA1PLT) were experimenting with Slow Scan Television (SSTV). SSTV sent higher resolution pictures at a slower frame rate, typically taking 8 seconds to send a complete image. Below is a picture of some of the first commercial SSTV equipment that was made available to US hams.

Robot 70 (monitor) & 80 (camera) SSTV system introduced in 1970
I wasn't able to find exact prices for SSTV equipment like the ROBOT 70 & 80 but period articles seem to indicate you wouldn't get much change from $1000 in 1970 for a complete SSTV station. This is equal to around $5000 USD today.

Friday, January 13, 2012

An oscilloscope clock - Recycling vintage equipment without destroying it.

As a fan of vintage electronics, and vintage technology in general,  I love to see things being re-used rather than being dumped in the trash. This has the very desirable effect of preventing sometimes toxic chemicals from being released into the environment and reduces the demand for new parts that can also involve toxic chemicals during their manufacture.

The only downside to this recycling is that frequently the original function of the equipment is lost so I was pleased to see this creation from Bob Alexander. He has combined one of the oldest types of test equipment with some of the newest microprocessor based devices to bring us a Oscilloscope Clock that still functions as an oscillloscope!

Heathkit oscilloscope with AVR Oscilloscope Clock module
Bob ran into some problems while installing the AVR Oscilloscope Clock Module but was able to invert the horizontal output from the clock module before feeding it into the scope. To read about his build in detail have a look at : An Oscilloscope From the Trash

A small modification to the rear panel to allow setting the clock and switching between clock and scope.
Check the video below for a demonstration of the Sparkfun AVR Oscilloscope Clock Module in action on a significantly newer oscilloscope.

Thursday, January 12, 2012

Mapping your ADIF logfile to Google Maps

I had tried Google-mapping a while back with limited success, manually kludging together several utilities until I got a Google map of my contacts. This new utility from K2DSL makes the operation VERY easy.

Just select your adif log file (You can download yours from Logbook of the World or export one from your logging software) and click Upload and Map. You may want to enter your home grid square if you have issues with the contact origin or the map looks strange as I did.

Select your adif file, set your home gridsquare and map it!
The output will be familiar to anyone who has used Google maps but with the additional option of being able to download a kml file to use in Google earth!

France, on a magloop, in the garage.
With Google earth it becomes obvious very quickly which way your antenna favors and where you are reaching. Clicking on a contact opens up the time, band and mode information if it was recorded in your adif log, very smart.

East coast - yes, West coast - not so much.
A very useful piece of work from K2DSL, available at his website

Amateur radio event helps youths connect to others around the world

An important part of Ham Radio is public service and while not every ham has the time or ability to contribute, those that do are able to connect to communities in a very meaningful way.
Ham Radio can provide a communications service that is very different to the corporate product of AT&T or Comcast. Ham Radio is an essentially a grassroots organisation drawn from the community itself.

A recent article in the Daytona Beach News-Journal highlighted some of the activities during Amateur Radio Kids Day ...
Mark Estes, Correspondent for the Daytona Beach News-Journal

PALM COAST -- Herschel King Sr. Park was abuzz with activity as members of the Flagler Amateur Radio Emergency Service Organization and Flagler Palm Coast Amateur Radio Club joined in Sunday for the American Radio Relay League's national Children's Day event.

Before the event officially began, there was plenty to do as members of both clubs readied a number of radio set-ups. With the help of members of Palm Coast Boy Scout Troop 402 various antennas were deployed in the trees in preparation for a day of contacting amateur radio enthusiasts around the continent.

The dozen Boy Scouts, along with parents and Scout leaders, bicycled 10 miles to the site as one of the requirements for their cycling merit badge. Eight of the Scouts are working toward their radio merit badges and for some, this outing would complete the requirements for the badge.

During the day, other families visited to learn about amateur radio and this was good news for Bill Schwartz, Flagler County emergency coordinator for ARES.

"We're introducing amateur radio to youth," Schwartz said. "For the Scouts, they're going to try to get some requirements for their merit badges. For us, it's practice so if there were a disaster we could set up an HF station anywhere."

The order of the day was to have the licensed adults make the initial contacts and then hand the mic over to their charge for a conversation.

"We expect to be able to get the United States, Canada and South America," Schwartz said. "The kids have to spend 10 minutes on the air for the merit badge. So far it has been all theoretical for them. There are certain places where we're going to try to get in touch with other kids."

Any contact and conversation was good. If the prospect of talking on the radio to strangers, mostly adults, was a bit daunting, Jake Dobson, 11, never let on. Despite a bit of local interference, Jake confidently held the mic and made the appropriate acknowledgments while learning a bit of conversational radio shorthand from John Woika. He made his required contacts in good order.

"It was interesting and fun," Jake said.

The day started a little rougher for Coby Queen, 12, as an equipment malfunction resulted in a fall and a scraped arm during the 10-mile bike ride. Things started slow for him on the radio as well. The first contact his adult partner, Norm Riquier, found was in an extended conversation; the next faded before he could talk to them. Getting a good signal was elusive, but eventually Coby contacted New Mexico and then, Guatemala.

Michael Levin, 13, and Ian Medley, 16, got a bit of a treat when they did their radio work in Mike Lee's communications van. Chief innovation officer at Palm Coast Data, Lee designed and equipped it as a proof-of-concept van seemingly capable of very type of communications except smoke signals. Lee and assistant emergency coordinator Eddie Cail served as adult partners for Levin and Medley.

The older hams would certainly like to see some of the participants take up amateur radio as a hobby.

"We have a 119 merit badges in the program and the boys usually go into some profession or pick up some hobby out of these during their lifetimes," Scoutmaster Tony Conti said.

This is the first time the Flagler clubs have participated in the national Children's Day event, but they expect to be doing so again in the future.

"We're hoping to do more of these throughout the year, keeping the kids active and give them something to do," Cail said. "The bands are really hot right now for a lot of radio stuff so we're hoping to make some good contacts and let them see what it's like to get on the air."

More information on ARRL Kid's Day is located here : Kids Day 2012: Sunday, January 8 & Saturday, June 16

Monday, January 9, 2012

PACO C-25 Capacitor Tester

I recently attended the Houston Vintage Radio Association post holiday dinner and participated in the auction held after the meal. It was a great evening and if you have any interest in vintage radio I would suggest getting in touch with the HVRA and becoming a member.
Among other things I walked away with at the end of the evening was a PACO Model C-25 capacitor tester.

The PACO C-25 differs from my Healthkit IT-22b in that it tests both regular and electrolytic capacitors as well as using a 40Mc oscillator to enable a rough measure of capacitance using a bridge circuit.
Most of the time, with vintage vacuum tube equipment, capacitor values need only be "in the ballpark" to function perfectly so a high degree of accuracy is not required. For more accuracy I have a Heathkit impedance/capacitance bridge if required.
I have my doubts how accurate the tester would be when measuring capacitance "in circuit" but otherwise it looks to be a very useful bit of kit!
The users manual should be available here and the circuit diagram is shown below.

Friday, January 6, 2012

More cheap power supplies ...

Looks as though more folks have been putting "bargain" power supplies to the test and finding them wanting. This time it is a 5 volt USB power supply purchased in the UK that fails to deliver its advertised load.

At 560mA load the voltage has already fallen below 3 Volts, a far cry from its rated 1 Amp!
As most power supplied are simply featureless black boxes it would be nice to be able to rely on the specifications stated on the outside ... sadly you can't as the video below shows.

Thursday, January 5, 2012

Winter Field Day and generators

With Winter Field Day coming up some radio operators may be running your stations using gas/petrol generators. While you can just drop the generator down outside and start it up you really should, for safety, have a ground rod set into the earth.
Although the system below does have a ground rod placed in the earth I'll leave it to you to discovery why it is not going to be very effective ...

Not the right way to ground a generator system, "A" for effort though.

Cheap accessories can damage your expensive electronics

The power supply below looks just like a normal Canon power supply, right down to the correct model number and style. If you dig deeper, or just try and use this power supply, you start to notice things aren't exactly what they appear to be.

It seems as though there are some great deals to be had on Ebay for electronic accessories but like the saying goes, "You get what you pay for!".
Giorgos discovered the difference when his Canon camera started behaving strangely and was fortunate enough to have the experience and the test equipment to show just how poorly his bargain power supply performed.
So, before you buy a cheap power supply or battery charger for your cell phone, camera or iDevice, check out the video below and decide for yourself if its really worth saving a few dollars.

Monday, January 2, 2012

Deathrays and the garage home-brewer

In days past home-brewers would often be at the forefront of new and developing technologies. Apple Computer got their start in a suburban garage, Marie Curie refined radium in little more than a garden shed and the founders of Hewlett Packard worked out of a home garage in Palo Alto.

Unfortunately we moved away from encouraging kids to "tinker" in the garage and instead we've supplied ready made entertainment in the way of game consoles, demographically targeted TV and an endless series of extra-curricula activities ... all ultimately aimed at preventing boredom and keeping kids busy.

To see some impressive tinkering, take a look at this great build from Its certainly something that could be dangerous if used incorrectly but the assumption that something is unsafe unless proved otherwise and the knowledge to know the difference is sometimes better that relying on a commercial manufacturer's assurance that everything is ok ... because sometimes it isn't.

X-Ray Machine from
I don't think well raised kids will take to the streets in rampaging mobs if they are allowed to become 'bored' and I think there is the possibility that through their inventiveness they will discover and create things we haven't even imagined. Given the tools, basic education & a measure of respect we could see more garage pioneers in the coming years. While I understand the value of robot kits and 'following directions' I am more enthusiastic about the Maker movement and the great selection of micro-controllers and electronic building blocks they have created.

Looking through a hard-drive using the X-Ray source