I want to have a single polarity supply of +9v how do I extract it from the voltage supply? to connect to an Amplifier with a 2nd order low pass active filter
What is the voltage that you want? What do you want supply? Normally I use a old desktop power supply that have enough power for almost everything that I want to supply. Other thing that I normally use is an old mobile phone charger that have 5V and 500mA. So it depends of what do you need.
EDIT: I think I don't read well the question. Now I see that you need +9V to an Amplifier. What is the power that you need? The +9V can be +12V? (I ask this because in a PC desktop you have +12V, but you don't have +9V)
hello luisilva
thank you for replying my question sorry for my question due to my lack of knowledge
i want to design a 0.5w audio amplifier i want to use a power supply of a single polarity +9V going thru a voltage regulator to get a 5V to power up the audio amplifier TDA7052A
Use a 9v plug pack and a LM7805 regulator. Look at data sheet for the regulator to show you how to connect it.
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kenneth619:
hello luisilvathank you for replying my question sorry for my question due to my lack of knowledge
i want to design a 0.5w audio amplifier i want to use a power supply of a single polarity +9V going thru a voltage regulator to get a 5V to power up the audio amplifier TDA7052A
If you want to use a regulator you don't need +9V, you need something higher than +5V, so you can use +12V too. So, my suggestion is still valid.
hello luisilva Your 5 volt cel charger is better Idea for the Op a 9 volt battery will not last long with a Lm7805 they waste battery.. The op be better just using the 9 volt the TDA7052A will be happy with it.
i want to use a power supply of a single polarity +9V going thru a voltage regulator to get a 5V to power up the audio amplifier TDA7052A
That chip can operate at a voltage up to 18V
TDA7052A
Why do you want to run it at 5V ? That defeats the whole purpose of using a chip that operate at 9V (and higher).
).
it is the specification of the assignment and i am trying to figure out it
i would also love to use a direct 9v to power it up 
kenneth619:
it is the specification of the assignment and i am trying to figure out it
While such perverse assignments are not unknown, perhaps you had better post the actual text of the assignment here.
If it is (nineteenth century style) on paper, photograph it. Must be perfectly, focused, no more than 1000 pixels wide.
the 0.5w audio amplifer design should use no more than a single polarity supply of +9v supply source
the the audio signal both voice and music are sourced from a function generator. the level of the base-band signal is 200mVp-p for frequencies ranging from 10hz to 20khz
the end user has a choice of selecting music or voice or mute mode this is to be done via remote control which sends an appropriate control signal to a transistor switching circuit the control signal from the remote control will be simulated using SPDT switches. the recommended supply voltage to the transistor switching circuit is 5v to be generated from the 9v supply
i have done all and everything of the circuit without the single polraity 9v i used a +-9V
so i am trying to get the last part right of a single polarity
help been trying for days
So you've designed the entire circuit ignoring the requirements for a single polarity power supply.
Are you allowed to generate -9V, so that the entire circuit still only requires a single 9V supply? There are switching regulators that can be wired up to change 9V into -9V.
So there is clearly no requirement for a regulator other than that in the Arduino - whatever the Arduino has to do with this in the first place.
For a half watt audio amplifier, you use an LM386. It can be completely muted and shut down to a low-current quiescent state by pulling down the bias control pin. Only about four capacitors (including the Zobel network with one resistor) are required for the whole audio amplifier section.