Home security and automation
by Angga on Jan.08, 2012, under Electronics
Right now there are already many solutions to secure our homes. There are also a bunch of home automation projects done professionally or by DIY. But what is home security & automation anyway? Why does it matter to automate our homes? The answer lies in efficiency. With automation, you can simply text a message to lock & secure all doors in your house. Or using your mobile phone you can for example video-call a specified number connected to a surveillance cameras in your house, to see what’s going on while you’re on vacation. Or getting an automated text message/email notification in case of any trespassing on your property while you’re away. Isn’t it amazing? Of course it is!
Home automation is revolutionising home security, home entertainment and even cooking and gardening job. At its heart lies electrical control system allowing you to adjust and alter lighting, appliances and machinery to suit environmental changes. What’s more, home automation can be controlled effectively with a LCD screen or even our TV, via the telephone line, remote control automation, internet, wireless systems or on a mobile smartphone like I mentioned above. Sometime ago I stumbled over a site specialising in home security and automation equipments. Just for the sake of curiosity, I searched for a solution on home video surveillance and found out there are so many appliances that you can control easily. One of its product, video intercom system, for example, allows you to see the visitor and open the door/gate without directly going there physically. Or if you are back from work, you can just call your home number to unlock the gate.
Not only that, everything from TV, video, music, alarm, CCTV, lighting, heating, air conditioning, blinds and curtains can be controlled as well. Even bath and shower controls can be accessed either remotely or via conveniently located control panels. They can be controlled from any part of the home, or even outside it. Control of your lighting, blinds, temperature and audio video systems from several locations can simplify your life, as well as make your home’s atmosphere comforting, inviting and exciting.
For now all this facilities might be hard to reach if you only have a limited budget. But don’t worry, sometime in the near future this will all be very commonplace.
My New Samsung Galaxy S2: A little review
by Angga on Oct.29, 2011, under Gadgets
Di post kali ini saya akan mereview smartphone Android Samsung Galaxy S2. Ini adalah smartphone yang sudah memiliki sistem operasi Android Gingerbread 2.3.3 out-of-the-box. Kalau dilihat dari spesifikasinya, ni hp termasuk yang paling canggih saat ini lho, bayangin dari sekian banyak hp Android di luar sana, ada berapa sih yang punya prosesor dual-core Exynos 1.2GHz ARM-Cortex A9 dengan memori RAM 1GB dan layar Super AMOLED Plus-nya Samsung? Belum lagi fitur-fitur yang wajib ada buat smartphone seperti Wi-Fi a/b/g/n, internal memory 16GB, kamera autofocus 8 MP, serta dukungan jaringan 2G/3G/HSPA+ yang bakal buat pengalaman berselancar di dunia maya jadi sangat nyaman. Ini foto smartphonenya biar gak penasaran, hehehe.
Spesifikasi lengkap smartphone ini bisa dilihat di situs GSMArena. Di sana reviewnya juga ada dan sangat lengkap. Di post ini yang akan saya ulas adalah pengalaman saya menggunakan kameranya, kemudian akan disambung di post selanjutnya tentang proses upgrade ROM ke Android versi 2.3.5.
Kesan pertama waktu baru buka bungkus: Wow! Tipis bangettt! Layarnya yang lebar surely bakal bikin betah browsing foto-foto dan nonton video nih. Tapi apa kemampuan shooting foto & capture videonya bagus? Menurut saya, setelah coba-coba ngambil video pake kamera 8MPnya, kualitasnya memang bagus sekali. Bisa merekam video dengan resolusi 1080p Full HD (High Definition)!
Tapi ada dua kekurangan yang saya temukan dengan kamera smartphone ini. Yang pertama video di resolusi 1080p ini ukuran viewing angle-nya kecil, karena saat perekaman video, area pixel yang dipakai untuk merekam adalah daerah pixel dengan ukuran 1920×1080 yang diukur dari tengah-tengah sensor. Jadi video yang terekam memiliki sudut pandang yang sempit. Yang kedua, saat merekam di tempat dengan pencahayaan yang minim, videonya kadang-kadang tersendat-sendat dan tidak mulus.
Solusi untuk masalah yang pertama untuk sekarang adalah dengan merekam di mode 720p (1280×720). Di mode ini kameranya memanfaatkan seluruh pixel sensor, jadi viewing anglenya lebih lebar. Memang, dengan memilih resolusi yang lebih kecil, detail yang terekam menjadi berkurang, tapi saya lebih rela memilih mode ini daripada mode 1080p dengan sudur pandangnya yang sempit. Untuk masalah yang kedua sepertinya belum bisa saya temukan. Mungkin dengan upgrade ROM yang lebih baru masalah ini baru bisa diatasi. Atau jika Anda sudah punya solusinya, share dengan saya ya melalui comment di bawah 
Cloud-based Storage: What is it?
by Angga on Oct.08, 2011, under Uncategorised
Recently I have visited a website which, well you guessed it, is a site which reviews cloud-based storage providers. But what is a cloud-based storage anyway?
As you can see above, cloud-based computing is a service which provides users access to remote data/software via the internet. For example, you can create a spreadsheet using Microsoft(r) Excel on your PC and then upload it to the cloud provider, say Google Docs, and when you’re mobile you can always open your favourite web-browser from a public computer or your mobile phone to edit your file straight on the Google Docs without using Excel. Pretty convenient, right?
Of course, you can put all your important documents there as a backup. So if you forgot to bring your important data you can always get it via the internet. Not to mention that big and bulky external drive you used to bring along with you everywhere.
Here are some reasons why a cloud-based computing and storage is preferred today over individual backup solution:
- Cost, almost every cloud-based storage provides their service free-of-charge. Nothing is cheaper than free! Some charges a fair amount of money per year for features or additional storage space, though.
- Device and location independent. You can access your data anytime and anywhere as long as you have access to an internet connection. But who doesn’t nowadays?
- Reliability is improved. The storage devices in a cloud-based service almost always use redundancy, so your data can always be accessed reliably and safely.
- Maintenance. Why should we? Let them do it.
- Green solution. A centralised and multi-tenancy properties of cloud-based storage will reduce the energy consumption of individual users, because they can be put into a pool which utilises a common computer hardware system.
With these reasons, I predict that by the next two years (2013) we all would utilise at least one cloud-based solution, might that be the storage service or computing service. We would have access to our documents any time of the day, share them to other people, or even edit them collaboratively.
The site I mentioned above (www.top10cloudstorage.com) offers comparison to currently available cloud-based service providers. It is ranked based on price, performance as well as customer’s satisfaction. The review mainly deals with the features of each providers, connection speed, bonuses (for example free domain for each purchase), etc. Personally I would recommend this website for selecting the best online cloud-based service providers.
An Upgrade to My Gainclone Amplifier
by Angga on Feb.26, 2011, under Electronics
Well, it’s actually an additional pair of LM3886T chip amplifier, which I ordered again through a local supplier for the same amount of money (IDR 150000 or US$16.70). I previously have made 4 marking for drill holes because I intended to make two pairs of amps, but since I’ve only got a pair, I drilled two holes first for the mounting of the ICs in the middle of the heatsink. So basically I just have to add two more drillholes and that’s it.
Two pairs it is
Side view
The previous and added pairs are configured for bridge mode operation into 6Ω speakers for 2 channels. This was simply achieved using just one 100kΩ resistor from one of the LM3886 output pin to the other’s inverting input pin. As usual, more info on bridging amplifiers can be found in the Wikipedia.
Menambahkan feedback untuk regulasi tegangan pada PSU
by Angga on Feb.16, 2011, under Electronics
Kali ini postingannya pake Bahasa Indonesia aja deh, soalnya sejak pertama kali direlaunching blog ini pake English melulu. Hehehe. Lanjut. Setelah saya mengobservasi beberapa PSU switching yang menggunakan IC PWM Controller TL494CN, dari kesemuanya (ya, benar, semuanya!) tidak ada satupun yang memanfaatkan fitur op-amp bawaan IC tersebut. Padahal op-amp itu bisa kita manfaatkan untuk mengatur/meregulasi tegangan keluaran power supply sehingga tetap stabil walaupun bebannya berubah-ubah. Anda yang kurang paham dengan regulasi, mungkin tahu dengan IC regulator 7805. Nah, prinsipnya sebenarnya sama, yaitu tegangan keluaran PSU diumpan-balikkan ke op-amp IC TL494CN. Op-amp ini akan membandingkan tegangan keluaran tersebut dengan tegangan referensi internal IC PWM sebesar 5V. Apabila melebihi atau malah kurang, lebar pulsa yang diumpan ke MOSFET akan disesuaikan sehingga tegangan keluaran PSU akan tetap stabil walaupun bebannya berubah-ubah.
A collection of my SMPS
by Angga on Feb.05, 2011, under Electronics
This is about my SMPS (Switch Mode Power Supply) for the gainclone amplifier I previously have posted. An SMPS differs to the conventional linear 50Hz power supply (pictured below) in that it converts mains voltage using a smaller HF transformer. This small size is made possible because the current is switched (or turned on and off) by a pair of switching transistors or MOSFETs at more than 40000 times a second (40 kHz) compared to the 50 times of the mentioned linear PSUs. Further information is available at Wikipedia here if you want to know more.
Mains Transformers, Left: EL-type, Right: Toroidal
My LM3886T-based Audio Amplifier
by Angga on Jan.26, 2011, under Electronics
Here’s my attempt at making a stereo LM3886T-based amplifier a couple of months ago, back in 2010. The gainclone gives a very good sound quality. It is like dead when the input signal is absent, no hum, hiss or any other noise. What you see below is the front view of my amplifier. You can see the amp on the left side along with an analogue meter, and the switching power supply on the right side of the picture. I also added two tweeters on the desk wood for more high frequency response.
Front View of the Amp and PSU
Hello world!
by Angga on Jan.22, 2011, under Uncategorised
Another classic hello world post from me!!
Well, there’s not much to say except that this is my first blog post. I used to have a blog which is based on bEvo, but due to some hosting problems some time ago, all its contents was gone before I’ve had any chances to back it up. Anyway, here I am now, posting (probably) useful notes and words about my activities. Hope you enjoy your stay 
