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[SOLVED] Using ULN2803 instead of UDN2981

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vbdev

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I have used UDN2981 in my project to drive 4 seven segment displays, 2 big LED's & 1 buzzer. The Vs pin(9) is connected to 5V supply of micro-controller. Resistors for displays & LED's are chosen accordingly.

Now my problem is that the sound from buzzer is not enough on field. I will have to increase the supply of the buzzer (it can work from 3V to 24V). To solve this issue, I have two solutions.

1. I can use the unregulated 12V DC supply for pin9. The current limit resistors should be modified accordingly. OR

2. Can I use ULN2803 instead of UDN2981, so that I can power different parts with different voltages? LEDs will be connected to 5V whereas buzzer to 12V. CAN I DO LIKE THIS. Of course I will have to modify my code.

I think 2nd alternative is better. As the ULN2803 is cheaper. Secondly in 1st option, losses will be slightly higher. What do you people suggest.

Thanks.
 

In my opinion, ULN2803 is the best possible option to use in this case. I agree that it is a lot cheaper compared to unregulated 12V DC supply. In addition, it has more option as well.:smile:
 

Thanks, I have decided using ULN2803. For displays I will use 5V, whereas for buzzer, I will use 12V for louder sound.
 

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