by Francesc Casanellas:
This design was done to get a sealed keypad for very wet environments (in my particular case, showers for swimming pools). The keypad needed to be able to detect slight pressure on a stainless steel plate 0.4mm thick. Apart from water protection, the solution offers an esthetical finish, as the user side is absolutely flat, with nothing visible other than the silkscreened print. Another advantage of this type of keypad is that it is vandal-proof. The core of the sensor is a piezoelectric disc, the type normally used as a buzzer. I chose the Murata 7BB-35-3. With 35mm of external diameter, it allows a sensitive area of about 20mm diameter.
Water & vandal-proof keypad uses piezoelectric disc as sensor and buzzer - [Link]
Raspberry Pi has been very popular small computer board. It’s initial layout is quite flexible that allows it to use as standalone computer or embedded device with controllable I/Os. Probably standard Raspberry Pi is more oriented to be small single board computer, where you can connect peripherals like keyboard, mouse, display, Ethernet. The I/O part seemed to be left on a side. Eventually extension boards started to appear to fill the need of functionality like ADC, DAC, more digital I/Os. Eventually you end up stacking stuff on top like Arduino. But we like elegant things don’t we? So Raspberry Pi team has been working on different Raspberry Pi concept – Compute module. This is smaller module which have same BCM2835 processor, same RAM. Instead of SD flash there is a 4Gbyte flash memory. Practically this is it. Module is traced on DDR2 SODIMM sized PCB which actually fits this connector.
Raspberry Pi Compute module - [Link]
nevdull @ instructables.com writes:
Tactile switches (a specific type of momentary switch) are everywhere and they are especially popular on DIY electronics and microcontroller boards because they are well suited to act as a boot option or reset switch. Particularly, momentary switches are switches that don’t save their state when you depress the switch. That is, when you push the switch (and while you have the switch depressed) the circuit is ON, but once you let off the switch it reverts back to OFF.
Use a Momentary or Tactile Switch as a Pushbutton Switch - [Link]
Home automation is the residential extension of building automation. It is automation of the home, housework or household activity. Home automation may include centralized control of lighting, HVAC (heating, ventilation and air conditioning), appliances, security locks of gates and doors and other systems. This provides better convenience, comfort, energy efficiency and security. Home automation for the elderly and disabled can provide better quality of life for persons who might otherwise require caregivers or institutional care. Nowadays, semiconductor companies develop IC that integrates the system as a whole. One of which is NXP Semiconductors which they develop Home automation modem IC TDA5051A.
The TDA5051A is a modem IC, specifically dedicated to ASK transmission by means of the home power supply network, at 600 baud or 1200 baud data rate. Its single chip power line modem is equipped with protection of its output power stage and AGC (Automatic Gain Control) of input signal. With simple coupling network, this power line modem is compliance with EN50065-1 power line communication standard. This power line modem circuit uses ASK (Amplitude Shift Keying) for the modulation, and operates on 5V supply.
A home automation system integrates electrical devices in a house with each other. Devices may be connected through a computer network to allow control and may allow remote access from the Internet. Through the integration of information technologies with the home environment, systems and appliances are able to communicate in an integrated manner, which results in convenience, energy efficiency, and safety benefits.
- TDA5051AT modem IC
- Schottky Diode
- 68Ω Resistor
- 2.2MΩ Resistor
- 7.3728Mhz Oscillator Clocks
- T 630mA Fuse
- General Diode (2 units)
- 2uF Capacitor
- 47 nF/X2 Capacitor (3 units)
- 470 µF Capacitor
- 100 µF Capacitor
- 1 uF Capacitor
- 10 nF Capacitor
- 5 µF Capacitor (2 units)
- 1 mH Inductor
- 47 µH Inductor (2 units)
- 1N4006 Diode
- 250 Supply Vac
- Positive Voltage Regulator
Power Line Modem for home Automation - [Link]
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]