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THE 741 OPERATIONAL AMPLIFIER
USED AS AN AMPLIFIER - A SIMPLE EXPLANATION

V. Ryan 2007 - 2009

 

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741 Operational Amplifiers (also known as Op Amps) are used in a range of circuits. They are generally used to amplify weak electrical current in a circuit. Radios, stereo systems, headphones, TVs and many other electrical products include an operational amplifier as a component in many of their circuits.

Circuits such as moisture sensors, light / dark sensors, movement sensors, sound sensors etc.. often need operational amplifiers in order for them to work properly.

 
 

The circuit below is part of a larger alarm circuit. When it detects movement (ie. an intruder) it sends a signal to the main alarm system which sounds the siren. Without the Operational Amplifier Integrated Circuit the signal would be too weak for the main alarm system to detect. The Operational Amplifier increases the signal so that it is strong enough and the main alarm circuit sounds the siren.

Make a list of other electrical products that you think have operational amplifiers as a component(s) in their circuits.

   
 
 
 
 
 
   

Ed often plays his electric guitar without it being plugged into a speaker/amplifier system. This is good for the general public as he is often plays out of tune. His music cannot be heard next door which means his next door neighbour gets a good nights sleep.

   

However, recently he has bought a powerful speaker with his pocket money. Inside the speaker is a circuit that amplifies the sound of the guitar. This circuit includes a 741 Operational Amplifier which ‘amplifies’ every sound the guitar makes by a factor of 100. The volume of the music is now extremely loud and consequently his neighbour cannot sleep

QUESTION:

Explain the main reasons for including an operational amplifier in a circuit for a product such as an alarm sensor or a radio.

     

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