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They stopped carrying what their original customer base wanted. Tandy disappeared, Dick Smiths has got even worse and I don't know how they are still going.

But then JayCar came along. Picked up all of their old customer base and have been making a killing ever since. Jaycar's buzz line is "Better. More Technical" you can go in there an they have bins of components - Love that shop - http://www.jaycar.com.au/

Let me introduce you to the convection cooled heatsink. No moving parts, powered entirely by the dissipated heat itself, it just has to have sufficient surface area for the job (and they scale up more easily than actively cooled systems).

How many $20 LED lamps have you bought? How many $10 ones? ALL SHIT. You must spend real money on an LED lamp to get one that even has current limiting, let alone power regulation.

Abso-freaking-lutely. I too have wasted good money on rubbish el-cheapo bulbs that produced bugger all light back and die in no times - the "50 crappy white LEDs in a downlight case" types for example were completely bogus. But things are improving. For example, $30 will get you one of these, which I've had in the kitchen for a while now and it's worked flawlessly. Mind you, decent LED downlights are still damned expensive. We have four of these in our dining room. They work beautifully, even with the dimmer, and came with a pretty good warranty, but at $100AU a pop you'd damn well hope they did!

One of these will do.

These ones have a display.

In conjunction with getting solar power at home, I've also set up real time usage monitoring.

I've had a stand alone power monitor for a while (our state Government offered them + a bunch of CFLs and other stuff for $50). However it doesn't have any PC connectivity. One day I was looking in the meter box, and I realised that the sensor was just a clamp meter around the input wires.

I already had a clamp current meter attachment for my multimeter (which also has RS232 out), so I put the clamp around the same incomming wires, connected it to my multimeter and then to my PC (via an RS232 -> USB cable). From there I have some scripts to take readings and enter them into a database as well as a web interface for output. Fortunately for me, the meter box is just outside of the room where the PCs are, so it was easy to wire up.

I actually did this setup in a number of stages. Initially, I used some software for my multimeter to plot / save to text file the raw (amperage ) data. I then started batch importing it into the database and calculating wattages etc from there. Now it all happens automatically. Readings are taken at 1 minute intervals.

Even though I already had all the parts, they cost well under your budget. From memory their original costs were:

    * clamp meter attachment (Digitek QM1565) $25 (see http://www.jaycar.com.au/productResults.asp?keywords=QM1565&keyform=KEYWORD&SUBMIT.x=0&SUBMIT.y=0)
    * multimeter with RS232 (Digitek QM1538) $50 (NB. this model is no longer available, don't know what an equivalent would be)
    * RS232 -> USB $6 (from eBay)

Now I live in Australia, so your meter box setup may be different to ours. In mine, the meter and circuit breakers etc are mounted on a board in the box. This board has hinges on one side, so you can swing it out to get behind it. That's where the wires are that you need to put the clamp around. Obviously you want to be very careful back there, but there *shouldn't* be any bare wires etc. If in doubt, you could get an electrician to do this for you.

I've put a sample of our median usage and production on Imageshack http://img31.imageshack.us/i/electricityusageandprod.png/

Here is the usage and production for a single day http://img163.imageshack.us/i/usageprodction20100915.png/

Having this type of data is great for tracking down where your usage is going.

This one ?
http://www.jaycar.com.au/productView.asp?ID=KJ8916
I have seen a few of these kits and they look all too slow and imprecise for doing even a simple thing like playing an arcade game. I don't know this one, is it different ? Do you think it could change a joystick position 2 times per second during 10+ hours ? If so, I think I have to make a participation to Australia GNP...

I have a solid timber table I built up to support a printer. The working area is under the table and the cat food goes in a bowl on the floor under the table. Attach two Jaycar robot arms under the top of the table so they can reach down. Attach a USB webcam to the underside of the table looking down with a light source. Put a linux box on top of the table with a power cable going off to a power point. The whole setup goes in the garage with a cat flap in the door.

Linux box has a wifi connection to my in house server which has a static IP address. I hack up a web interface on the server which sends commands through to the linux box, probably through ssh or similar. Linux box controls the robot arms through a simple parallel port interface and relays.

We have little packets of cat food which you tear off to open. I nail the packets around the inside top of the table so the robot arms can tear them off, invert them and drop food on to the cat food bowl.

If it fails, then, well the cat can actually feed itself if it needs too, but it won't be happy with us. Or I can phone somebody to check on it.

Here is your chance to corner the world market for the next big thing and have Bill Gates cleaning your shoes. As a bonus, they are even on special! Remember me when you're rich? (Can I have a research grant now? Please?)

Try the Funway into Electronics series from Dick Smith or the Short Circuit Series from Jaycar. They are written to be simple enough for kids but are actually soundly based and suitable as a first step for adults. Each project aims to demonstrate a principle, includes explanation and builds on previous projects to form a short course. The books are the most important thing. The mentioned shops sell accompanying kits but the components are all generic and can be picked up at any electronics store around the world.

Funway was my first exposure to electronics and today I am a professional electrical engineer (with a few intervening steps required).

well u better grab these before there gone!! http://jaycar.com.au/productView.asp?ID=ST3117

I've used the RFID kit he's installed on his front door before.

There is absolutely no encrypted handshake between the RFID tag and the reader. Hence an attacker could VERY easily conduct a replay attack using an easily duplicated tag. Given that the tag he uses is implanted into his arm, anyone that walks past him on the street could steal his front door key.

But I guess this isn't much of an issue for fellow geeks, because what sort of geek walks outside their basement and gets within the vicinity of other people in the first place?

My laptop (from where I am currently posting this) uses a 65 watt power brick. It's an 18 month old Lenovo 3000 N100 with 1Gb RAM, dual core 1.8GHz CPUs, and other bits.

Despite using a 65 watt rated power supply I know it is using between 25 and 27 watts (thanks to a Jaycar power meter).

When you are doing the maths for determining power useage you need better data than the stickers on the boxes, or the manufacturer supplied data. They will give you the peak power consumption expected, but the typical day to day useage is often a lot lower.

Given how little power it consumes, I leave it switched on 24x7 and just replaced a few more light fittings around the house with compact flourescent lamps and planted a tree.

Or this

• Teach Yourself Electricity and Electronics (4th ed.) by Stan Gibilisco
• Guide to Understanding Electricity and Electronics by G. Randy Slone
• Getting Started in Electronics by Forrest M. Mims III
• The Art of Electronics by Horowitz and Hill - IMHO an excellent reference, not as useful for the newbie
• Basic Electronics by Bernard Grob
• Understanding Basic Electronics by Larry D. Wolfgang
• Practical Electronics for Inventors (2nd ed.) by Paul Scherz

I know Jaycar http://www1.jaycar.com.au/ have had a fuel cell powered toy car out for a while. They also have the 30mW Proton Exchange Membrane (PEM) Fuel Cell for sale seperately.

Here in Australia, I noted with interest from Jaycar (http://www.jaycar.com.au - an electronics distributor), had a fuel cell model car in their latest catalogue, along with a (small) fuel cell. Generates hydrogen given electricity, produces electricity given hydrogen. The model car is here:http://www.jaycar.com.au/productView.asp?ID=K T2525

http://www.jaycar.com.au/products_uploaded/product Large_9528.jpg
http://www.jaycar.com.au/productView.asp?ID=KT2525
They also sell fuel cell's separately!

http://www.jaycar.com.au/products_uploaded/product Large_9528.jpg
http://www.jaycar.com.au/productView.asp?ID=KT2525
They also sell fuel cell's separately!

White LEDs can only be constructed by combining the output of a red, green, and blue LED.

Not correct. White 3.3 Volt LEDs in the standard 2-pin package (see link) are conventional blue or UV LEDs with a flourescent reflector, and produce a blue-white light. This is the kind you find in cheap LED torches.

http://www.jaycar.com.au/productView.asp?ID=ZD0195 &CATID=&keywords=white+led&SPECIAL=&form=KEYWORD&P rodCodeOnly=&Keyword1=&Keyword2=&pageNumber=&price Min=&priceMax=&SUBCATID=

There are also RGB LEDs, but these are considerably more expensive and have four pins (one for each colour, although there are two blue LEDs in the package). These types are designed for large video displays, and are more complex to drive because each colour component works at a different voltage, but they can produce a more convincing white (even though it is only peaks in the spectrum, not the full range).

http://www.jaycar.com.au/productView.asp?ID=ZD0270 &CATID=33&keywords=&SPECIAL=&form=CAT&ProdCodeOnly =&Keyword1=&Keyword2=&pageNumber=&priceMin=&priceM ax=&SUBCATID=573

Also, LEDs are gallium based, not silicon.

http://www.marktechopto.com/Engineering%20Services /leds-drivers-displays-driver-technical-articles-d etailed/leds-drivers-displays-driver-technical-art icles-history.cfm

White LEDs can only be constructed by combining the output of a red, green, and blue LED.

Not correct. White 3.3 Volt LEDs in the standard 2-pin package (see link) are conventional blue or UV LEDs with a flourescent reflector, and produce a blue-white light. This is the kind you find in cheap LED torches.

http://www.jaycar.com.au/productView.asp?ID=ZD0195 &CATID=&keywords=white+led&SPECIAL=&form=KEYWORD&P rodCodeOnly=&Keyword1=&Keyword2=&pageNumber=&price Min=&priceMax=&SUBCATID=

There are also RGB LEDs, but these are considerably more expensive and have four pins (one for each colour, although there are two blue LEDs in the package). These types are designed for large video displays, and are more complex to drive because each colour component works at a different voltage, but they can produce a more convincing white (even though it is only peaks in the spectrum, not the full range).

http://www.jaycar.com.au/productView.asp?ID=ZD0270 &CATID=33&keywords=&SPECIAL=&form=CAT&ProdCodeOnly =&Keyword1=&Keyword2=&pageNumber=&priceMin=&priceM ax=&SUBCATID=573

Also, LEDs are gallium based, not silicon.

http://www.marktechopto.com/Engineering%20Services /leds-drivers-displays-driver-technical-articles-d etailed/leds-drivers-displays-driver-technical-art icles-history.cfm

LCD screens for in-car DVD systems are available in the 6- to 10-inch range, in 4:3 and 16:9 aspect ratios, and are getting cheaper all the time.

Although they tend to have composite or S-video inputs (you're not really after high resolution, are you?) there are some now getting VGA inputs and touch screens for in-car computer applications. You can just register that the screen has been touched and ignore the actual location.

Jaycar use linux to access their stock control system at the point of sale. Strange that their website uses ASP, though.

Jaycar electronics use Linux on their POS systems. Their sock managament system seems to just use an ssh connection to a server off somewhere else, though.

Its a pity their website uses asp.

like this one?

... has similar stuff - like this. And that's not the only one. they do various versions for, say, in-car use.

interesting way of sharing music - your own mini radio station

For us Aussie geeks there's a similar place called Oatley Electronics. A mixture of surplus gear with new stuff and kits. I've never dealt with them but they always seem to have interesting gear.

There's also Jaycar, which has stuck to the hobbyist theme. It's a shame that Dick Smith sold Dick Smith Electronics all those years ago. Now it mostly focuses on consumer goods (stereos, TV's, CD/DVD players, etc) rather than on components and kits. My dad told me that back in the day, most stores had people that could assist you with kit building.

Polycrystalline cells don't have this problem, and I can buy top shelf "BP Solar" branded cells with a 20 year warranty! Similar $/Watt too. What does this mean for the MSK-clad building? Will its enviro-friendliness fade? And what effect does age have on its transparency/opacity?

The Planet/ServerMatrix do a simular thing. They get those shelves and just dump ATX towers. See a live picture here. (Warning: Java applet). I feel sorry for the support guy there.

Personally, for my home clustering project where Mini-ITX is not a option and I don't have real room for towers, I'm going to pick up some Jaycar 2U Rackmounts for AUS $95. Keep in mind that I don't need to place hard drives etc. in there, and that my power supply needs will be taken care of externally.

That I've got a catalogue today with a fuel cell kit.

It's from an australian company, and it costs AUD299 so it's probably not much help - but it does look like some sort of generic kit. No specs on the cell though :-(

Umm, oops thats actually www.jaycar.com.au

Its a really really good company with quality products. There speakers are 1/3 of the price of brnad name and do just as well in tests. Sorry but I really love them. They are a geeks wet dream.

(b) gradually dims - better if you control light brightness with puslse mechanism, but ideally for night riding/racing, you want full beam headlights all the time.

I've been wondering about getting on of these head fitting lights from Jaycar this year (not its in AU$, so it's cheap!).

What I'd really like is something that floodlights the area in front of the bike equivalent to about 50Watts of halogen lighting, with a rechargeable battery life of 4 hours or so.

Here I think you have some confusion about power sent to the speakers and power as it comes out of the wall. If your speaker system has an AC to DC converter like mine, you can read the wattage rating off that. The "100 watts x 4 channels" is refering to audio power at peak. I think the draw from the wall socket would be much lower. Maybe an audiophile can back me up/discount me on this.

IANAA (i am not an audiophile), but...
So you're saying that more power comes out of the speakers than is drawn from the wall? I don't think so!! It is true though that many speaker manufacturers specify peak ratings (e.g. PMPO - peak mean power output) to make the speakers sound more powerful, generally the better (whatever that means) systems will specify the speaker power in RMS (root mean square) wattage (at a specific speaker impedence, often 8ohm), therefore a 20W RMS speaker is much more powerfull than a 20W PMPO speaker. As a (probably grossly inaccurate) thumbsuck rule, you can divide the PMPO rating by about 8 to get the RMS rating. If the specs on the speakers say 100W, it is more likely that it is a PMPO spec than an RMS one, unless the speakers and AC/DC converter are pretty large.

That said, these simple AC/DC converters are usually very inefficient themselves, and usually employ a linear voltage regulator to give an accurate DC output. The linear voltage regulator (very basically) essentially "wastes" the difference between input and output voltage times current as heat power, and the transformer itself is also usually fairly inefficient, so if you are blasting your speakers constantly at full volume, I'd guess you can expect the power drawn at the wall plug to be at least 1.5 times the power that is dissipated in the speaker coils. If the PMPO rating is 100x4 channels, we could maybe expect an approximate RMS output power of about 50W, so the input power at the wall socket could be about 75W (at a very rough guess).

Obviously, the voltage at the wall plug is much higher (and is AC), and the current drawn is lower, but the product (taking into account RMS power calculations) giving the power drawn from the wall plug must be greater than (or, if you had a perfectly efficient power supply for the speakers, equal to) the power dissipated in the speaker coils... (check out this googled pdf: power calculations)

So, to answer the original request, yes, the power drawn at the wall is less than the 400W the original guy seemed to think it was...

Down here in OZ, Jaycar Electronics is selling "Superbright LED keyring torches". I've got a red one, better for night vision, and it's bloody great. I remember seeing an IR one and even an UV one (apparently good for looking for counterfeight money or something...), but they don't appear in their web catalog. Neat little things. My only complaint is that it's a little hard to push the rubber button to turn it on, and that you have to push on the other side to turn it off. Just a little awkward and easy to get mixed up when going only by feel.

Jaycar Electronics in Australia have a kit for a white/pink noise generator that is supposed to help with this. The thoery is that the white noise drowns out the ringing but isn't intrusive. I don't know how effective it is. Jaycar Web site

Vacuum fluorescent displays - still look the best. Once again Jaycar has purchased a substantial quantity of a quality Futaba brand vacuum fluorescent displays. Each digit measures 6.0mm(H) x 3.5mm(W), 11 digits in all. The display also features an apostrophe in the top right hand corner of the digits, and a semicolon (;) in the bottom in all 11 digits. Electrical and mechanical data is incl in the price.

Jaycar has been selling these in Australia for a while.