Kamis, 31 Oktober 2013


Nowadays most of instant drink will be sold in can or a tetra pack, and we use to throw it away once empty, this time when you drink one, do not throw away the can, it can be recycle it into sweet LED lamp :)

Prerequisite  :
- A few used food/drink can,
- A super glue
- 2 pcs LED 5w white (6-7.8v )
- 2 pcs diode 1N4001
- 1 330uF/16v electrolite capacitor
- 1 SMR8807 7volt switching regulator
- 1-2m cable
- any power adaptor with voltage 12-24v, In this project we use 12v 1amp el cheapo adapter :)

We use two slim can, and one small one, it already look shiny.

Most of the component needed can be found easily in any local electronic shop or even using recycle part from your old radio parts, for SMR8807 which you can buy it here, and on ebay

Take out both side of the cans, so it will look like a cylinder, soldered the cathode of 1N4001 into the anode side (+) of each LED, this diode will function to limit the current ~1amp and decrease the input voltage of 7v into around 6.5v to meet the LED power requirement. Glue each set of this LED into the can inside wall, make sure the LED metal is really stick into the can, this will help dissipate the heat from the LED, no need additional big heatsink, each can will provide heatsink for each LED.

Connect both diode 1N4001 inside each can in pararel to SMR8807 output.

Schematic of the circuit :

It's alive! It's alive!


Once you have test both side of the LED, you can glue both into the third can, the third one will serve as a mounting to the wall.

Adding colorful plastic sheet can give certain color mood :)

See, we can recycle used can, save the electricity and having a beautiful wall night lamp :D

Minggu, 08 September 2013

Driving a 12V Fan and an Android mini TVBox

Yesterday we got an interesting picture from one of our customer showing an application of SMR8812 driving a 12V fan and SMR8805 driving an android mini tv box using a single IBM laptop power supply.

Automatic Battery Charger using SMR8814

In this application we would like to re-use common switching supply that been use for printer, or LCD, mostly come with 19V or 24V, for charging a 12V battery.

The original circuit is adapted from eleccircuit 12v charger.

Basic idea is remain the same from the original circuit, a comparator is use to detect if the battery voltage has been lower than what has been set by potentiometer VR and value of zener diode ZD1, when comparator is high, it will set transistor Q to ON to drive relay. The relay will set connection from DC input into SMR8814, D1 will limit surge current and provide polarity protection, since SMR8814 is a fix 14v switch mode dc converter, adding a D2 will drop the voltage to approximately 13,5-13,8v to charge the battery, it will also prevent the battery current to reversely damage the charging power supply. 

Selasa, 30 Juli 2013

Active PoE Spliter

Using the above circuit you can transform a non PoE device into an active PoE device and still making use of your current PoE injector or PoE enabled power source device such as Routerboard RB750UP, or combine it with UBNT Tough switch PoE (24V) to power cctv or wireless router with non POE capability.

Rabu, 24 Juli 2013

DIY 10W LED Light using SMR8809


AC source from AC power line is converted using step down transformer into AC voltage of 12, or 24V, the alternating current is then rectified using a full bridge diode, C1 100-470uF providing filtering before going into dc-dc converter, be sure to choose voltage rating twice the AC voltage input, the SMR8809 will have output 9V, since this is a constant voltage regulator, we still need shunt resistor R1 to convert it into current source and connect it to 10W LED,  voltage that run into this resistor is about 1v or less, so dissipation heat should not be an issue for single emitter, but just be sure to have enough power rating, a 1 watt resistor should be enough for driving one 10W 8.5-9.2V 1000mA LED.

Senin, 22 Juli 2013

5V to 3.3V converter

Pada beberapa sistem mikrokontroler dibutuhkan sumber catuan yang berbeda dan sering kali menjadi masalah tersendiri ketika dibutuhkan daya yang mencukupi antara kedua sistem tersebut,

Regulator tegangan multi output dengan delay.

Multi output voltage regulator using SMR88xx

Using SMR88xx we can make multi stage DC regulator with delay turn on with each of the stage.

C2, C3 and C4 is optional, internally SMR88xx has a decoupling ceramic capacitor, but you may want to add some filtering capacitor along the line.
For 3Amp you may use 1N5400 for forward diode, and 1N4001 for 1Amp current, this diode will function as protection circuit and a simple current limiter, alltough the best protection for current will be a fuse.
12V will on first, followed by 5V, when the 5V is on it will trigger the 3.3V to turn on.

DIY USB 5V Car Charger

DIY USB 5V Car Charger using SMR88xx

This car charger can provide 5v 1 ampere from car cigarate plug, the D1 will provide polarity protection to SMR8805 and limit the current to about 1 ampere. ZD1 is a zener diode 5,6v that will provide extra protection circuit, LED1 and R3 basicly is only provide voltage indicator.

Solar Panel / Car battery Vdc regulator

Solar Panel / Car battery switching Vdc regulator

SMR88xx switching regulator replacement for 78xx

Adaptor Switching Sederhana

Selamat pagi, hari ini kita akan mencoba membuat regulator sederhana dengan menggunakan IC hybrid SMR88xx

Adapun Fitur SMR88xx :
SMR88xx - Drop in pin to pin compatible High Current DC-DC switching converter replacement for 78xx Regulator.

Features :
Wide Input Voltage = 5.6Vdc-30Vdc
High efficiency >=90%
High output current up to 5Amp.
built-in Soft start.
Low ripple voltage.
Thermal Shutdown protection
Over current protection
low heat dissipated compare to Linear version of 78xx.

Many selection of output
SMR8801-2 1.2V,
SMR8801-5 1.5V,
SMR8802-5 2.5V,
SMR8803-3 3.3V,
SMR8805   5V,
SMR8807   7V,
SMR8809   9V,
SMR8812   12V,
SMR88CC   custom Vdc output.

low heat dissipated compare to Linear version of 78xx.

Tipikal rangkaian regulator dengan linear regulator 78xx adalah sebagai berikut :

Rangkaian ini sangat populer digunakan, menggunakan trafo stepdown untuk menurunkan tegangan dari AC 220v ke tegangan DC 9v, menggunakan C1 dan C2 sebagai tank circuit dan filter ripple dari jembatan penyearah dioda full wave D1. Input 9V ini kemudian diturunkan oleh 7805 menjadi 5v dan difilter kembali dengan C3, termasuk salah satu sirkuit yang populer, namun punya kekurangan disipasi dayanya lumayan besar sehingga ketika output maximum 1-1,5ampere maka disipasi dayanya (9-5)*1amp = sekitar 4-6watt tergantung besaran output, dan daya yang dihasilkan terbatas, memang ada alternatif lain dengan menambahkan driver current transistor untuk mendapatkan arus yang lebih besar, namun kerugian tipikal yang di alami sebagai linear regulator tidak dapat dihindari, terlebih jika input tegangannya semakin jauh berbeda dari output keluaran 78xx ini.

Alternatif sirkuit lain yang cukup mudah digunakan dan punya susunan pin yang sama dengan 7805 bisa menggunakan SMR8805

Dengan efisiensi hingga sekitar 90%, disipasi daya untuk keluaran yang sama 5v 1amp hanya sekitar 0,5watt atau kurang, Daya sia sia yang menjadi panas dapat ditekan hingga ~77% dibandingkan dengan menggunakan 7805. Rangkaian juga menjadi lebih flexible karena tidak akan menambah rugi rugi daya ketika transformator diganti dengan tegangan yang lebih tinggi (6-30v) serta mampu menghasilkan arus yang lebih besar dibanding regulator linear biasa, komponen yang harus disolder juga semakin sedikit dan sirkuit menjadi lebih ramah lingkungan :)