Circuits made from necessity

Circuits made from necessity

  September 28, 2012    Tahmid

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LCR METER with PIC16F88

 

 In SMPS circuits, it is necessary to know the inductance of the inductors and transformer windings. However, it is not possible to know the inductance without the use of a meter for measuring inductance (eg LCR meter). In earlier stage of my venture in SMPS circuit design, I could not procure an LCR meter for use. So, I made one using 16F88 PIC microcontroller for my own use, taking help from internet. It has been made sometime in 2008. I still use it.

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PICKIT2 Clone

 

Circuit 1

 Circuit 2                      

When I was in class six, my father introduced me to PIC microcontrollers and gave me a programmer. After one year, the programmer got damaged. I failed to procure a new one as programmers available here were expensive universal ones - programmers for PIC only were not available. So, I made programmers for myself, taking help from internet and this PICKIT2 clone is my latest one - made sometime in 2010. Circuit 1 is the prototype constructed first on verroboard and Circuit 2 is the one I made on PCB after modifying existing designs collected from internet. I am still using Circuit 2 for programming all 8-bit and 16-bit PIC microcontrollers for my use.

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REMOTE CONTROLLER FOR 2 LIGHTs and 1 FAN

My mother complained that for morning prayer, getting up from bed and switching on the light becomes difficult for her and hence, she asked me whether I could make a remote controller to switch on lights without getting up from bed, which she saw in her sister's house (Chinese made). So, I made one to turn two lights on/off and to turn on/off and control speed of one fan using the existing remote of our Sony TV. Later on, I found that it has good commercial value as well.

It is made using a 12F675 PIC microcontroller. The microcontroller is powered off a non-isolated resistor-capacitor based auxiliary power supply. The microcontroller decodes the signal it receives from the IR sensor (PNA4602). The signal is given from the Sony TV remote. The protocol used by the remote is SIRC, so the microcontroller decodes the received signal according to the SIRC protocol. The microcontroller then turns on/off triacs for switching on/off, as well as using pulse skipping modulation for controlling speed of the fan. I made the code using mikroC compiler.

The SIRC protocol used in my remote controller:

The SIRC protocol uses a pulse width encoding of the bits. The pulse representing a logical "1" is a 1.2ms long burst of the 40kHz carrier, while the burst width for a logical "0" is 0.6ms long. All bursts are seperated by a 0.6ms long space period. The recommended carrier duty-cycle is 1/4 or 1/3.