Minggu, 16 Maret 2014

Current Source Switching Mode SMR88xx

Hi all,

Happy Monday, wish you all have a great weekend,  now I would like to update what I found, apparently all SMR88xx series (voltage source) can be turned into current source switching mode regulator, this mean we all can have a stable current source switching driver with wide input, it can be use to drive almost any LED in series or parallel, and other applications that need current source regardless of the voltage, great.

I'll come into detail later on,

Meanwhile this is what it look when turned into current source, and driving a 5w LED.

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,