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Microcontroller power supply

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#1 chushi


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Posted 23 October 2017 - 06:34 PM

Hello, I am doing my mini project on atmel AT89C51 . But I face problems in power supply. Since to test my project,I created a power supply of 5V for the microcontroller, motor driver ic L293D, and two dc geared motor. The circuit is:

230V > transformer (230/8v) > 8vac > bridge rectifier circuit > 1000microfard capacitor 25v( parallel). > voltage regulator L7805 > 220 microfarad,63v(parallel)

And the out is taken across this capacitor. I dont know whether I could use a 63v cap for 5v needs. I do because it was only available.

When this supply is given to microcontroller Vcc , it is not responding. And when I checked this power supply using multimeter, I noted that this 5vdc power supply also contains 10vac! I also checked this with a 9v dc battery, same here too. WHY A DC SOURCE OR A BATTERY CONTAINS AC CONTENT??? Is this causing microcontroller problems?

Thanks a lot guys!

Edited by chushi, 23 October 2017 - 06:42 PM.