DIY: Turn your bike into an e-bike for yourself in 5 steps - Step 1: Build the battery from recycled laptop batteries

BH bike modified to electric with prokit 901; a real pleasure to climb hills with it

Some time ago I had in mind to change my bike to convert it to an e-bike; it was increasingly more difficult for me to climb the hill to my home with sections of 14% and get sweating profusely in summer is not very comfortable to say something.

In the next 5 entries I will tell you the details of how I have adapted mine for 500 € (if you want it without complications, since you have € 1100):

1: We'll see how to prepare the battery with Li-ion 18650 batteries

2: Putting the engine on the bike

3: Preparing the housing for the batteries in the box

4: Connecting it all and programming the controller

And finally, it is important to have good brakes; Bike weight reaches 25 kg.

Voltage monitor cell; important to know the status of each pack

Calculating the cost of lighting according to the type of bulb

Picture: r (Energy Trends)

With the price of electricity rising steadily, and the prices of CFLs, correct evaluation of what type of lighting to use at home is necessary to not lose sleep over the bill. 

Recently I commented the advantages and (current) limitations of the LED; this post by a simple calculation table, see what it would cost to illuminate a room, hallway, or whatever depending on the type of lamp chosen. 

Ex LED lamp with E27 and 420 lumens with 6W consumption.; glows like a traditional 30W

I entered the data for five similar lighting lamps (1000 lumens); comparable to a 75W traditional incandescent bulb: 

1. E27 LED lamp ; 10 / 12W consumption
2. Philips CFL; Consumption 15W
3. Halogen; 50W, their advantage is that they last longer and shine a little more (because it uses another gas).
4. Traditional low power ; use halogen technology.
5. Traditional 75W

Irretrievably Erasing a hard drive: Secure-erase your data

Before throwing a computer that has no basis in the trash, think twice, because some unscrupulous could recover all your information even if you have formatted the hard disk.

Note: When you delete files are not physically deleted from the disk, but for reasons of speed and recoverability only the "direction" of the file is deleted from the hard disk. It happens when we format a disk similar to "quickly".

Previously we discussed how to recover data from hard drives (my favorite for this is Redo Backup , which will soon explain their fascinating abilities).

To avoid this, it is best to make a low-level format with a free program for personal use as eg.HDD Low Level format Tool .

Report: LED lighting, present and future of lighting

LED Bulb E27 6W to 220VAC

The lighting technology LED is already present and future of lighting, with prices a few years ago was prohibitive but are becoming more affordable and superior performance compared to other light sources, making them rapidly depreciable . 
They are currently recommended especially where they can not be placed compact low-power, as in bathrooms and hallways (CFL does not hold up well off and frequent or cold locations such as garages on): 

• LED technology is low power consumption, with savings of 80-90% compared to incandescent and improving every year.
• Ecological; no Mercury or polluting materials, emits no UV or infrared.
• Lifetime: Duration between 20,000 and 50,000 hours, depending on the quality of the lamp and the LED.
• Instant light, as fast as incandescent or halogen.
• Can be switched on and off as many times as you want without reducing useful life.
• Because of its semiconductor format optimally support vibration and shock; it will work even if the casing is broken, contrary to the other technologies.
• With more lumens per cm2 than halogen and CFL, and more efficient, have great ability to be miniaturized (flashlights, televisions, etc).
• Uniform light without shadows into the light, available in warm white or pure, or all colors to consumer tastes.
• Design only limited by the imagination thanks to its compact size and low temperature of LED; the possibility of sharing the light sources as we want by the lamp allows innovative designs integrated into the environment ; are valid for any type of use.
• As in the CFL, some models can be adjusted easily by varying the electric current applied to a regulator. Very useful for environments that wish adaptive dynamic light environment (eg., We could program Arduino ambient lighting that adapts to the light coming through the windows, or human presence, illuminating more where people are ).

However, its disadvantages, but salvageable, are: 

• The angle of the light from an LED is directed at an angle of limited brightness;There are lamps with angles between 30 and 240; laterally to illuminatemanufacturers seek designs where multiple LEDS pointing to different parts or modern reflectors, which can be a problem of space, and rising from the lamp, but gradually being solved with lenses that scatter light or formats led targeted less.
• Are still relatively expensive when it comes to high power systems where other lamps are almost as efficient and cheaper, such as sodium vapor (80 lm / W, but also more polluting and less durable), since the ledes require heat sinks (this will change as improve its luminous efficiency).
• The LED works better the white light is emitted (temp. Color approx. 6000K), for more warm yellow light to be mixed with another color decreases performance slightly.
• Require temperatures below 70 ° C to maintain their life, so they need efficient heat sinks, which increases their cost.
• They are very long lasting, but its intensity decreases with time; for an LED with an expected life of 25,000 hours, you will after that time a light intensity of 70% the original, but it will illuminate; not "merge" normally, but they fade away.
• The high power LEDs must wear a suitable light fader so that if viewed directly by accident, do not harm the view (some are more intense to look at the sun directly).

This entry will discuss technology LED and its many advantages, the influence of operating temperature on the duration (disarm a lamp) and uses more current recommended (for those who want to minimize investment while taking advantage of technology); go for the LED is a very good investment, ecological and profitable.

Save with LED technology 

Changing brushes on washing machine

Too often, there are washers in perfect condition thrown in recycling because repair costs are too high and not worth repairing, and the consumer has to assess whether it is worth it because you do not know if it will give more problems or not, and with the aid renewal of appliances, makes you thinking twice.

But if it's a quality machine, and low power consumption with less than 10 years like this AEG, and the problem is that the brushes are worn (AEG usually eat them fast), always it is worth to repair it; two wipers is 15 €.

To access the brushes Lavamat AEG-5011 / 5012 have to remove the rear cover or case, which involves exposing half the labadora (handy for technicians, a success of AEG), takes several screws, both at the top, of which only removal of those to the rear half of the housing, and more difficult, leading to the sides at the bottom behind a plastic plug, because you have to use a hexagonal socket wrench to 8 I think it is.

Get visual output from your Arduino with only 2 resistors (and a screen with Video-in)

We just need a TV-Out cable and a pair of resistors (1K and 470 Ohms) and use the library ofmdmetzle@gmail.com to show the output we want through video on any screen. 

Quite simply, no added circuitry.

Is not this just great? The simplicity to power ...

The timing and signal connections to Arduino

This video explains in detail:

How to use a thermistor or temperature sensor with Arduino: Code for the NTC/PTC types

Checking the operation of the program

One of the most common applications of Arduino is an electronic temperature control via a simple thermistor (temperature sensor), for example if we want to activate a fan when the temperature rises to a certain value in a computer / engine, or activated by an relay a circulator motor in a boiler when we detect that the temperature is rising (and thus the fire is on), as we did in home boiler with AKO or Keld thermostats, only with Arduino will not only allow us to activate a device, but allowing us much more play, controlling and managing other parameters for our stove, such as temperature of the fumes, or air injected into the combustion chamber, etc, as already explained us Oscar Gonzalez in BricoGeek from a project from Xoel (from Asturias).

A thermistor (thermistor) is simply a resistor whose resistance varies as its temperature varies (though non-linearly); there are many kinds, but in this post talk about one NTC (Negative, whose resistance value decreases as the temperature increases), and measure different temperature ranges of -50 to + 99 ° C in this case.If we measure a higher temperature, we would need a thermocouple type K or J, but we'll see later.  

But to use a thermistor whatever we can get, is not enough to measure the value of resistance and apply a rule of three, because as we said, is not a linear (but curved) value, with the biggest differences resistance with increasing temperature so hyperbolic.

To use a thermistor, or know their values ​​(datasheet), or we have to approach them; according to the formula Steinhart-Hart, we have to find a value, called β (Beta) (so-called value of characteristic temperature of the material), and use it along with your formula to get the C to a given value. Here is very well explained , and this explained the Steinhart-Hart formula .

Although it seems difficult to understand for those who give them bad math (like me), but do not worry, in the end you have a program that you can use and just change the header data (values ​​of two points, the resistance of your thermistor 25 and the actual value of your Arduino 5Vdc and little else) will be able to use it in your project without having to understand the formulas involved, but I prefer to go into detail for those who like it as much as me "why of things. "

But how do we calculate the β value? 

To obtain the value of β, using the Steinhart-Hart formula, give the values ​​of resistance and temperature at two different points, as far as possible from each other, for greater accuracy. The formula tells us that β is equal to:

Obtaining resistance values ​​of 25 and 100 (for example), we get β  

How to Build a battery for a Krautkramer USM 25 ultrasound equipment

Krautkramer USM 25 ( source )

Today was the challenge ahead: Search spare parts for rechargeable NI-MH battery 4.8V of anultrasound machine Krautkramer USM 25 Nr. 35274. 

The price for a spare rechargeable battery from the brand owner, GE, was outrageous, so I had to find a way to manufacture it and save good money. This battery is disarmed: 

It has 4 rechargeable batteries 1.2 V each; 1.2 * 4 = 4.8 Volts, wrapped in plastic and a PVC tube outside

The problem I couln´t find the appropiate battery with those measures; about 43 mm. . x Ø22 mm, but thanks to wikipedia and looking at types of batteries , I located your name: Sub C.

It's funny, because it takes a piece of PVC to separate one of them, I guess to make it harder to replace (spare parts worth their thing). And they go into a plasticized PVC cartridge.

Install Cyanogenmod on your Android: Give new life to your mobile

If you want a quick cooked rom like lightning, stable, without unnecessary extras that will occupy memory, CyanogenMod is one of the most refined Android ROMS and more support.

You can use the latest Android versions on the old cell (eg version 4.2 on a Galaxy 9003 whose support fell in version 2.3.6); you'll be amazed at what your phone is capable with an optimized software.

Moreover, so far the fact that other manufacturers present a different user experience was an obstacle for those who are used to the "quirks" and features our brand ever. With CyanogenMod does not occur, presenting a similar Android experience use the brand you use (like CyanogenMod is not supported for all phones, see first what development there for you're interested ).

These and other reasons I will mention below, made me opt for this cooked ROM for my Samsung Galaxy S3.

Top reasons to use CyanogenMod on your mobile

Upgrade your Samsung Galaxy GT-i9003 with SCL 10.2 CyanogenMod

If you want to enjoy the features of the latest Android 4.3, CyanogenMod 10.2 is now available to give new life to your mobile phone Galaxy I9003, as I said in the previous post ; Its main advantages are speed, enjoy the latest features of Android, and homogeneity in experience (plus it is very customizable). 

It is an ALPHA version, we have been testing and hangs / restarts occasionally (once every two days or so) so it is not recommended to use it yet, I would expect to take out a stable version, see page if it already is. According to the Developer the only downside, aside from those sporadic crashes is that video playback is not quite fluent, but we just have not noticed a difference. 

Attention: If you live in South America, they carry other types of modem / 3G Network, so you will not do this version. Looking for more information on websites of your country.

After having tested this equipment, it becomes faster than any other ROM, with a more streamlined interface and interactive user, and all the improvements of Android 4.3 (camera, security, flow, etc). In the video you can see the previous version 10.1, but it gives an idea: 

To install it, we do it through CWM (ClockWorkMod Recovery, a powerful boot utility), so the process is very safe and it is extremely difficult to turn the phone into a brick like this. 

If already you had CWM installed (for a previous modified ROM), only you would need to download the ROM, keep it in the SD card, reboot into CWM (Volume Up + Home + on) mode, make a Wipe Data / Factory Reset and clear caches and then install the rom with the option of "install zip from SDCard".

We'll see then what steps to take if you have the official version Samsung; the process is simple if we follow the letter will not have problems, I recommend that you read the entire article before getting your hands dirty, to understand some of the process and avoid trouble.