My 2µF

Yesterday I got another shipment with electronics parts, which is almost better than Xmas. Among other things it contained a remarkably cheap energy meter. They’ve also got a link to a c’t-article about energy meters there. For readers of adafruit blog, it is similar to a “Kill-a-watt”, but for 220V 50Hz. This one only costs 9.95€ at reichelt.de and can measure powers from 0.2W to 3.6kW (220V single phase). It’s ideal for finding ‘fake standby’ devices. It measures line voltage (V), frequency (Hz), current (A), effective power (W), total energy consumption (kWh) and cost (€). The price per kWh can be adjusted. A nice feature is the lack of any battery.

As my back is killing my right now, I won’t be going anywhere anyways. So I might as well crawl around my home and measure how much energy I waste. Maybe this will bore the little devils sticking hot needles into my back to death and they go away. Even if walking upright was a major step in the evolution of mankind, it comes at a price…

 

The measurements:

 
Wattages of some other devices:

 
Now many folks may think that 10.5W of standby power isn’t a whole lot, but an average year has 8760 hours. Multiply that by 10.5W and you end up with 92kWh per year, senselessly wasted! According to my measurements that would be enough to have about 30 full loads of laundry washed and dried! If you like to think about it in terms of money, 92kWh would cost somewhere from 14€ to 24€ depending on where you get the juice. That’s definitely enough for going to the movies and maybe having some food as well.

Assuming that I’m “better” than average in terms of avoiding the standby trap, let’s just assume the average guy/dude/dudess/single/singless/family also has a big stereo, maybe an XBox or PS3 + TV, radio, alarm clock etc. etc. – all running on standby power. Let it be 50W total for sake of this thought experiment. Now take a country like the USA (0.30 milliard people, it’s NOT billion dudes!)

 
Short intermission:

See also here. BTW, short scale is crap and the world is metric!

Where was I… right the USA. Again 300 million people, maybe about 100 million households wasting the above assumed 50W. That’s a whoppin’ 120′000′000 kWh a day, 43′800′000′000 kWh a year or the output of a standard nuclear power plant (2GW) running for 2.5 years nonstop.

Fact: it takes about 334kJ to melt 1kg of ice of 0°C. Doing the math one gets: 1 kWh = 3600kWs = 3.6MJ, therefore the very large number from above gets multiplied by 3.6 to give MJ. Dividing that humongous number by 0.334MJ gives about 472 million tons of ice or roughly 0.5 km³, a cube with sides of about 800m. 800 meters are about the same size as the new Burj Khalifa sky scraper, which was completed earlier this year.

Gasoline has an energy content of about 38MJ/l. Wasting said amount of energy is equal to burning about 1′000′000′000 gallons of gasoline. That would take your average 25miles/gallon car 1′000′000 times around the globe.

All of this waste because of “I’m off, really!” a.k.a. “Standby”. Personally I’m more than willing to make the very small effort and switch off my gear when I don’t need it. Awareness to energy waste should be taught at school (and it could be fun too), as well as “Shut off the lights when you leave the room!”.

/rant

Mystery link!

robert The Dump. electricity, energy, rant, standby, waste

A few days ago I visited my parents. The main purpose was to ‘deposit’ my new Lecroy WaveAce224 DSO. I bought it as a gift for myself, but I haven’t fulfilled all criteria to receive the gift yet. Therefore my parents are ‘guarding’ it for me until I’m allowed to have it. As Lecroy were offering a promotional sale on these, I just had to buy it right now.

I happened to see a pretty simple nitelite my mom likes to use. It comes with a base unit and a glass sphere resembling the planet earth on top of that. It only had a blue LED, and a pretty inefficient one as well. It was pulling 80mA and wasn’t any bright at all. The upgraded ‘thing’ now comes with an RGB LED and an ATmega168 microcontroller as the brains. The metal cap now works as a capacitive touch sensor.

As you can see in the video, as soon as you touch the base it changes color. In normal mode it slowly fades through all colors. When touched, it shows the delay time used for the fading encoded in red and blue. If it’s more on the red side the delay is large, if it’s on the blue side the delay is small. The longer you touch it, the more the delay is changed. I used an uint8_t variable to hold it, so it automatically wraps around to zero once it gets larger than 255.

Here’s a look at the somewhat messy innards:

The metal cap to the left connects to two pins of the ATmega168 microcontroller. Together with 2x 510kΩ resistors it forms a voltage divider. The cap has a small capacitance against ‘ground’ that can be charged through the resistors. The code of the CapSense library measures the time it takes until the ’sense pin’ changes its state from LOW to HIGH (RC-time measurement). By moving your hand closer to the metal base the capacitance is increased. In case the power supply is not grounded (wall wart), the measurement is somewhat limited, as the ground reference is missing. The difference is huge if you do the same measurement when connecting it to your PC (which is grounded). That’s why I had to set the threshold to 2 to get any result. When connected to properly grounded PC, the values reported by the code are magnitudes higher. It might have helped to install a copper ground plane, but that wasn’t possible. Together with the metal cap it would have approximated a parallel plate capacitor.

Closeup of the important parts:

The 1kΩ resistor glued to the ATmega168’s belly is used to bring the wall wart’s voltage down to a safe value. It’s a cheap one labeled to provide 3.5V. When loaded with the old blue LED it supplied 3.8V at 80mA. With no load it spits out 6V, which would kill the microcontroller. The resistor pulls about 5mA out of it which brings it down to about 5 volts, which is safe enough. The 10kΩ resistor is used as a pull-up for the RESET pin, 100Ω go to the red LED and the parallel pairs of 130Ω are used for blue and green.

Here’s the pretty simple code. It requires the Arduino CapSense library by Paul Badger.

A few words of caution:

Please make sure you’ve flashed a bootloader to the chip AND verified that it actually works BEFORE you start the solder job. I had flashed a bootloader, but as it turned out it was the wrong one. ARGH ARGH ARGH. I can recommend the ‘ATmegaBOOT_168_lilypad.hex’ one with a long enough wait phase. The other ones don’t give you enough time for manual upload. Fuse settings for internal RC oscillator: LFUSE:0xE2 – HFUSE:0xDD – EFUSE:0×00

As the chip is mounted belly up, it is VERY useful to draw a mirrored diagram of all the pins you’ll need to use + their function. If you don’t do this, you’re bound to make mistakes. Trust me on this.

robert Arduino., Electronics. AVR, dead bug style, free-form soldering, hack, LED, modding, RGB, soldering, upgrade

I’m just keeping my mind busy, ordering some thoughts and testing my memory.

Almost 20 years ago I was lucky to have a math teacher willing to teach our class ‘all about’ complex numbers. At that time there were some changes to the curriculum and he could have skipped that or chosen something else. I don’t remember what the alternative could have been, probably stochastics (I just couldn’t resist) ;-)

One part of it was analytical transformations. Of course it wasn’t called that way back then at school and we weren’t told what criteria complex valued functions have to meet to be called analytical either, because that needed knowledge about derivatives, possibly integration and a whole lot about a guy named Cauchy. And of course calculating derivatives and integrals was part of next year’s math curriculum.

But we were taught quite a lot about

And of course there’s the famous:

BTW, complex math is the source of the world famous Mandelbrot set.

Here’s what I’ve found in the deep chasms of my mind today:

This little formula acts as a mirror using the dashed circle of radius 1 as the ‘axis’. Funny things happen.

If I’m not mistaken this transformation here is actually not analytical. If it were it should reproduce the 90° angles of the square perfectly. One textbook application of analytical transformations is calculating equipotential lines and electric fields in unpleasant geometries. As everybody should know field lines and equipotential lines are orthogonal. This fact is preserved if transforming geometries of electrodes into a more pleasant shape, meaning that calculation becomes easy or even trivial.

And the last one:

Here’s the files that were used to create the images. Some Inkscape post processing is necessary.

circle_mirror.pl , makeplot_circle_mirror.txt

robert The Dump. complex numbers, imaginary unit, mandelbrot, math

I’m trying to save money.

Heating up water with electricity is madness. It costs a fortune and most likely fossil fuels were burned for that before. So why not use my gas/water heater and a simple bucket for getting warm water into my washing machine ? It only comes with a hose for cold water. The tricky thing is hidden in here:

This machine has a temperature sensor. Good. It’s also used by the on-board brain to lock down the lid if the contents are above 40°C. Why 40?

If you just fill the machine with hot water by hand and start it, it will pump out all of it again. To trick the machine, you need to start it and let it suck in some cold water and only then pour in more hot water by hand. If anything goes wrong the machine locks the lid. Of course that’s what happened. Fortunately the lid can be opened by removing power for 2 minutes. Unfortunately this also resets the microcontroller, but I found that one out too late.

Now all hot water will be pumped out again, but that is not what we want. As the machine is still hot inside tricking it by letting it suck in some cold water doesn’t help either. Because of the thermal lock-down the lid will stay shut. The lid must stay open while the machine runs in this case. Of course normally you’d just let it suck in some water and then add hot water by hand, but that only works once and with a cold machine.

Fortunately the machine can be tricked by pushing the lid lock switch by hand with the machine still open. Now you can add hot water. As the machine is hot and its brain thinks it favourable to lock the lid, the lid now cannot be closed anymore. Argh!

Outsmarted by a washing machine. But I’ve got sticky tape, HAH!

robert Electronics.

New Year is over, time to post something new to get the fireworks images out of the way ;-) Here’s a slogan that’s a perfect match to my current state of mind:

“Until you decide that NOTHING will stop you from success, EVERYTHING will.”

That one contains a lot of wisdom.

And now some images of snow (lots actually, I’m sick of it already), my new green 5mW DPSS laser pointer from Dealextreme, and some POV experiments. The laser pointer will come in handy once I’m done with my current occupation. I call it “The Bane”.

Riding my bike will be interesting in these conditions:

Losing some photons:

Much better:

Lissajous Figures. The first to calculate the frequency ratio and phase shift will get a little something:

More POV:

And now if you will excuse me, I’ll have to take a hot shower. Otherwise I’ll freeze to death outside. Probably I shouldn’t ride my bike, but at least it won’t be boring. Up till now I wouldn’t have thought that boredom in a more abstract sense could be so annoying – and that is an understatement.

Edit:

On second thought I shouldn’t call it boredom, but a massive shift of interest. The emotional subsystem of the human brain is as strong as ever, thanks to our distant ancestors, tiny rodent like mammals. Or in other words: RATS!

robert The Dump. DPSS, laser, LIDAR, POV, snow, winter