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In one of my projects where I use 89v51rd2 microcontroller, I connect one O/P pin to Electric AC bell through relay. My problem is when reset during switch ON, my O/P pin goes high and come down thus generating a pulse which the bell rings unwantedly. I want to avoid this unwanted ringing till my program gets control. Can anyone please suggest a solution?
Add an extra transistor to invert the logic for driving the relay. Then the relay will be released when the processor is reset, and only drawn when you hold the processor pin low.
That makes sure that the relay is only drawn when you are in control.
Thanks. You solved my problem.
This really has nothing to do with Keil software tools!
For many & detailed discussion on driving relays from 8051/8052/etc and derivative processors, go to http://8052.com and search for "Relay"...
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