lightnin9 @ instructables.com writes:
Now everybody knows it’s way smarter to just pay someone to host your website. But what not everybody knows is that it’s way more punk rock to Do it Yourself. So what follows are some tips / pointers / instructions for setting up your own home webserver (which will burn a scant 2 watts) using all free, open source software, a Raspberry Pi, and your home internet connection.
The emphasis here is on lightweight, which fits well with the Raspberry Pi. Sure, you can setup a blog with wordpress or Django, and they will run (I’ve tried it, at least with Django). But they probably will run rather slowly. Why? The rPi doesn’t have a lot of memory or processing power, and a database / front end model requires a decent amount of that. If your site / blog ever gets much traffic, it’ll likely buckle under the load. The answer? Just serve up plain old static HTML pages. It’s fast, secure, simple, and easy on the rPi’s limited resources. But rather than painstakingly handcodeing each new blog entry, you can use a static html generator like Pelican to make it easy.
Host your own blog from a $25 Raspberry Pi computer - [Link]
by Viktor Safronov:
Sometimes you may need a group of switches where, if any switch is activated, it deactivates the previously active switch. This Design Idea implements such a function with relays.
This “one and only one” function is often implemented as mechanical switches in which an actuator (usually a movable metal bracket) is used to switch contact groups on and off. When any switch is pressed, this bracket first deactivates all switches, then activates the pressed switch.
Exclusively select 1 of N relays - [Link]
We are always vulnerable to thieves but we don’t know when will they strike. When they do, it will be too late for us to notice that our property was already taken. This project helps alert the owner if a thief is picking a lock. It can be used on doors, luggage or anything else with a lock.
The concept is simple, if the lock is opened without our consent, an alarm will be turned on indicating an intruder. This circuit is based on a NAND gates configuration that will turn the switching side on or off.
In this project we used the HEF4011B, a quad 2-input NAND gate. The outputs are fully buffered for the highest noise immunity and pattern insensitivity to output impedance. The configuration of the IC HEF4011B produces a HIGH output if the input is HIGH. Based on the figure, when the wire loop is closed, the IC HEF4011B will have a LOW input, and when the wire loop is triggered, the IC HEF4011B will have a HIGH input which will make its output also HIGH. The HIGH output of the IC HEF4011B will then be inputted to the base of the BC547 transistor allowing the current to flow on the relay switching the indicator or the buzzer ON.
- HEF4011B quad 2-input NAND gate
- BC547 transistor
- 1N4007 diode
- 1kΩ resistor
- 4.7kΩ resistor
- 0.1µF capacitor
- 5V dc power source
Anti-theft Security Alarm Circuit – [Link]
Here is a very nice graph showing the most popular programming Languages of 2014.
Every year we release data on the “Most Popular Programming Languages” based on thousands of data points we’ve collected by processing over 100,000+ coding tests and challenges by over 2,000+ employers.
This gives us a pretty good idea on what the trends are for the upcoming year in terms of what companies are looking for. It’s data we hope will be especially helpful for new computer sciences graduates or coders looking to stay ahead of the curve.
Most Popular Programming Languages of 2014 - [Link]
“Click And See “ is a system supporting the search of electronic components. The idea came during yesterday’s shopping in one of the electronics stores , cabinets with electronic components fill the entire wall. When buying several different components , the seller needs time to find them first in your computer , then in the appropriate bins , and the queue of customers getting longer … To facilitate this, I designed a simple , wireless and easy to expand the system to highlight the drawer of the element that want to buy .
more info here: CLICK_AND_SEE_ENG
Click and See – find electronics parts with a click - [Link]
Get a free development board from NXP and enter a fun little contest for EEs, with actual prizes running right now. EEWeb.com is running the “NXP/AXP Low Power Design Contest” and it has some interesting (consumer style) prizes. You don’t often see contests like this with quality general interest prizes, and a good chance of winning.
The contest centers around using the the AXP1G57 low-power configurable multifunction gate in your project; the project can be a solution to a real problem or something novel. They’ll send you a free development board, just include it as part of your design project and enter. The board consists of four identical sections, and each section is an independently configurable device.
This contest is very easy to enter, and you can choose your level of commitment, from just answering a 10 question form, a short 1-page (250 word) essay, a reference design project, or creating a schematic/circuit diagram. You can even blog about your project and use that as part of your entry. The contest runs through the end of May.
Enter the 2014 AXP Logic Design Contest! – [Link]
Lightning detector that flashes when lightning strikes nearby.
This circuit picks up and amplifies signals in the 300 kHz range, where lightning makes a lot of noise that can be picked up with a radio. The antenna and receiver are tuned to 300 kHz, with the receiver’s output connected to an amplifier that drives the lamp flashing circuit, alerting you to lightning in the area.
Use the potentiometer to reduce the sensitivity to noise and still be able to detect lightning strikes. In addition to lightning, this circuit will also respond to noise from motors inside appliances like refrigerators, washers, and air-conditioners. Another easy way to affect the sensitivity is to take off the antenna, or lengthen it depending on the conditions. To get some confirmation while tuning the detector, you can tune an AM radio to the bottom the of the dial as well.
You can use this circuit to track weather, and be prepared for it. The circuit is small enough and can be placed in a project box or waterproof container to use, on a boat for instance. The lamp can be replaced or even used alongside a buzzer in this circuit to give an audible alert as well, so that constant monitoring of the circuit is not necessary.
Simple Lightning Detector - [Link]
An IR detector that sounds a buzzer when an IR beam is broken, meaning the IR signal is lost. A pulsed IR signal generator is necessary, but not included in this post. This project would be ideal for doorways or hallways to alert when someone enters or exits an area.
The IR sensor responds to pulsed IR, not ambient or continuous IR. This means that another transmitter project is necessary in order to complete this one! Note though that some forms of lighting like fluorescent lighting may interfere with the sensor. For convenience, the the buzzer is internally driven so that a only Vdc is needed to make a sound. In this case, the IR sensor senses 38kHz pulsed infrared light.
Pin 3 of the IR sensor is actually low (0V) while receiving a signal. When the sensor is blocked from receiving the IR signal, the sensor outputs a high signal to the comparator, which then allows current through the LED/Buzzer circuit, and alerting you that the beam is broken. In the Scheme-It drawing the LM311 IC is a grouping of three components, in a functional block diagram style, to show how it functions in the circuit beyond what the pinouts would show normally.
IR Beam Breaker Alarm Circuit - [Link]
The compact FPV system I have built is only about 20g, now even my mini quadcopter and micro hexacopter can carry this FPV camera and video transmitter. In this post I will share with you what are the parts you will need and how I made it.
Super light weight RC FPV quadcopter DIY solution - [Link]
Active analog filters can be found in almost every electronic circuit. Audio systems use filters for frequency-band limiting and equalization. Designers of communication systems use filters for tuning specific frequencies and eliminating others. To attenuate high-frequency signals, every data acquisition system has either an anti-aliasing (low-pass) filter before the analog-to-digital converter (ADC) or an anti-imaging (low-pass) filter after the digital-to-analog converter (DAC). This analog filtering can also remove higher-frequency noise superimposed on the signal before it reaches the ADC or after it leaves the DAC. If an input signal to an ADC is beyond half of the converter’s sampling frequency, the magnitude of that signal is converted reliably; but the frequency is modified as it aliases back into the digital output.
Designing active analog filters in minutes - [Link]