Thursday, January 28, 2010

4 Channel Remote Control Video Switch

In this project we developed 4 inputs (Audio and Video), remote control operated video switch for general home use. This design is mainly based on Microchip PIC16F630 8bit MCU, 4052 differential 4 channel analog multiplexer, TSOP1838 infrared receiver module and 7447 BCD to seven segment decoder. With a given schematic and PCB design users can switch 4 different audio and video sources using compatible remote controller. Current version of this project is work only with most of Sony remote controllers (which based on Sony SIRC protocol) and it can be easily extend to Philips RC-5 protocol with some minor modifications of PIC16F630 software system.

In this design we incorporate small single transistor video amplifier to its output stages to amplify the (chroma) part of video signal. Audio output stage of this system may not need any AF amplifier. (In the designing stages we notice some clipping of input signal in 4052 analog multiplexer, but it is not much noticeable in practical environment/use.)

At the time of testing we use Sony RMT-V408 remote controller with this project and it produces successful results. Basically this project support only numerical keys between 1 to 4 and program Up/Down (+/-) buttons of remote controller.

This system is design to work with 5V supply voltage and to get the optimal results it is highly recommended to use well-regulated 5V – 750mA power supply with this unit. To reduce the interferences place screen-wires to both audio/video input/output lines and place them separately from AC main-lines and PSU transformer(s).

Note : With the given source code system may respond to any, compatible Sony SIRC protocol base remote controller, but this may get some problems in practical environment. To avoid this problem please validate the value of remote_sys variable with your target remote controller. In here I’m not implement it because I do not have any Sony SIRC protocol compatible products.

The complete schematic, source code and PCB designs of this project is available to download at

Tuesday, January 5, 2010

Homemade ADSL Splitter

Nowadays DSL splitter is a common unit in telecommunication and it is used by most of the ADSL users to obtain the maximum performance of the connectivity. Technically DSL splitter is an analog LPF (low pass filter) which is used to prevent interferences between analog telephone device(s) and DSL support units.

In this project we describe how to build miniature ADSL splitter at home with grater simplicity and with minimum amount of cost. To build this unit user need to use few generic components which include pairs of 330µH inductors and 1R resistors, 0.0033MFD capacitor and three units of RJ11 PCB connectors.

We successfully test this splitter with our local ADSL connection and it gives equal performance of commercial DSL splitter.

The complete schematic and PCB diagram (Eagle) of this ADSL splitter is available to download at