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[PIC] how to control 230v using pic microcontroller?

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bhoobalan

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Hi friends,
i am doing a project based on pic16f877a MCU, i am using a transformer and and i want that 230 volt of transformer(and it must not exceed from 230v)to convert and give 5volts to pic MCU,how could i control this criteria?
Thanks in advance
 

Raj Gunaseelan

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Hi Bhoobalan,

You need a 230V/12V or 230V/9V step down transformer. Connect the primary of the transformer to the 230V. Now you get 12V or 9V AC on the secondary. Since microcontroller operates on DC, you need to rectify this 12V or 9V AC to DC. This is done by a full wave rectifier(using 4 diodes: see diagram). To obtain constant 5V from the rectifier bridge output, you need a 5V regulator. [The most popular regulator is LM7805(see diagram)]. The capacitors filters the voltage to help reducing noise and ripple. The current rating of transformer and the regulator depends on the current requirements of your circuit.

Check this link for the circuit diagram:
**broken link removed**



Raj Gunaseelan
 

bhoobalan

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Hi Raj Gunaseelan ,
Thanx for ur reply........ i want to vary the voltage b/w 0-5v(i don't want constant voltage)?
 

Raj Gunaseelan

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Do you want to supply power to the microcontroller or do you want to measure AC voltage? Why and how(using potentiometer?) do you want to vary the voltage?
 

kgshankar1980

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Hi Bhoobalan,

If you are talking about supply to the MCU, then usage of SMPS is the best. But you also had mentioned that you need varied voltage.

Why would you need a varied voltage for the power supply of MCU?
 

bhoobalan

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Guys, i am going to connect one lamp with MC, so that i want to vary the voltage b/w 0-5 v(for example fan regulator). And also,if there is any voltage fluctuation in main, it must not affect the lamp. for example,if voltage is <230 or >230 means it must not affect the lamp voltage(0-5v).
help me friends.........
 

kgshankar1980

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Are you trying to control the intensity of the lamp or only turn ON/OFF??
 

abhishekavr

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Use this concept and apply whenever you need to connect the high voltage with low current and voltage device.

Keep these things in mind.
Limitations of the voltage and current values of the IC.
Never exceed 80% of the maximum value.
So,

Drop down the voltage using a high wattage resistor.
Then use a bridge rectifier.
User an IC like 7805 as voltage regulator,
Add filter capacitors,
check the voltage and current in multimeter and the waveform in oscilloscope (there should be square wave only).

Then connect the IC.
 

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