Hello everyone
Recently I have decided to to expand my understanding of electronics into an area that I am sure means a great deal to many of you, making noise!
At first I was going to just buy myself some small pre made speakers with a built in amp for the TV in my room until I randomly came across this kit
http://www.ebay.co.uk/itm/TDA2030A-Audio-Amplifier-Amp-board-DIY-Components-kit-/220975826600?pt=UK_Sound_Vision_Amplifier_Parts&hash=item33732f86a8
I have never actually bought a kit like this before as I have been a bit dubious of them. I tend to do some research into what I am making then buy the parts myself and make it on a prototype board. I like having full control of what I am making and understanding how and why it works but this one was cheap and could be good for experimenting and using as a starting point. Still the biggest selling point was letting me see the schematic before I bought it.
I have also bought some TDA2030A Class AB op amps, like the above link uses, they were so cheap on ebay and are great to play with.
From what I have read about op amps they require a +- power supply (I am still developing my understanding of them) but the kit I bought (which works perfectly) uses a standard single power supply. I suspect that it manages to work without a +- power supply by either creating a voltage divider (but can't see how with the components it uses) or it adds a voltage gain so the output is all positive which is then removed by the output capacitor (not sure of technical term) to produce the +- output. Can anyone explain this to me please?
I have seen numerous references to LC(inductance capacitance) high/low pass filters and the first thing I picture in my head when I think of inductors is the voltage spike they produce when the magnetic field collapses. My first real electronics project took advantage of the voltage spike which I know can be damaging. I have found no mention of the voltage spikes in filter designs online. Is it simply not a problem or do they safely discharged into the capacitor?
With the op amp kit when I first tested it I used an old variable plug in transformer with selectable voltages just to test it out. I was surprised that the voltage had no affect at all on what was coming out of the speakers. I began at 12 volts and slowly reduced the voltage down to 3v and it worked perfectly at a comfortable volume. I did get clipping at 3v if I turned the volume up. It was interesting as 3v is well below minimum voltage on the datasheet. As long as there is no clipping does the input voltage matter at all?
Does sound quality benefit from voltage regulation, such as the 8712 voltage regulator? Or is a big capacitor all that is needed to regulate voltage from a mains transformer (not smps)?
How do I measure power consumption? I know audio amps don't follow the normal rules because the consumption is far from linear.
I realise I asked quite a bit, I have more questions but will leave them for now, I don't want to scare people off with a 1000 questions.
A couple of interesting/geeky facts my research found while searching online about audio amplifiers that may interest novices who are interested in this sort of thing.
If you have 2 speakers with an identical audio output and you unplug one of them what you hear is only 3dB quieter. So increase of 10dB doubles subjective loudness is but takes 10 times the power. Therefore if you want to upgrade to something that is twice as loud get something with 10 times the wattage.
The decibel is one tenth of a bel and named for Alexander Graham Bell
Recently I have decided to to expand my understanding of electronics into an area that I am sure means a great deal to many of you, making noise!
At first I was going to just buy myself some small pre made speakers with a built in amp for the TV in my room until I randomly came across this kit
http://www.ebay.co.uk/itm/TDA2030A-Audio-Amplifier-Amp-board-DIY-Components-kit-/220975826600?pt=UK_Sound_Vision_Amplifier_Parts&hash=item33732f86a8
I have never actually bought a kit like this before as I have been a bit dubious of them. I tend to do some research into what I am making then buy the parts myself and make it on a prototype board. I like having full control of what I am making and understanding how and why it works but this one was cheap and could be good for experimenting and using as a starting point. Still the biggest selling point was letting me see the schematic before I bought it.
I have also bought some TDA2030A Class AB op amps, like the above link uses, they were so cheap on ebay and are great to play with.
From what I have read about op amps they require a +- power supply (I am still developing my understanding of them) but the kit I bought (which works perfectly) uses a standard single power supply. I suspect that it manages to work without a +- power supply by either creating a voltage divider (but can't see how with the components it uses) or it adds a voltage gain so the output is all positive which is then removed by the output capacitor (not sure of technical term) to produce the +- output. Can anyone explain this to me please?
I have seen numerous references to LC(inductance capacitance) high/low pass filters and the first thing I picture in my head when I think of inductors is the voltage spike they produce when the magnetic field collapses. My first real electronics project took advantage of the voltage spike which I know can be damaging. I have found no mention of the voltage spikes in filter designs online. Is it simply not a problem or do they safely discharged into the capacitor?
With the op amp kit when I first tested it I used an old variable plug in transformer with selectable voltages just to test it out. I was surprised that the voltage had no affect at all on what was coming out of the speakers. I began at 12 volts and slowly reduced the voltage down to 3v and it worked perfectly at a comfortable volume. I did get clipping at 3v if I turned the volume up. It was interesting as 3v is well below minimum voltage on the datasheet. As long as there is no clipping does the input voltage matter at all?
Does sound quality benefit from voltage regulation, such as the 8712 voltage regulator? Or is a big capacitor all that is needed to regulate voltage from a mains transformer (not smps)?
How do I measure power consumption? I know audio amps don't follow the normal rules because the consumption is far from linear.
I realise I asked quite a bit, I have more questions but will leave them for now, I don't want to scare people off with a 1000 questions.
A couple of interesting/geeky facts my research found while searching online about audio amplifiers that may interest novices who are interested in this sort of thing.
If you have 2 speakers with an identical audio output and you unplug one of them what you hear is only 3dB quieter. So increase of 10dB doubles subjective loudness is but takes 10 times the power. Therefore if you want to upgrade to something that is twice as loud get something with 10 times the wattage.
The decibel is one tenth of a bel and named for Alexander Graham Bell