My first real project

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Hello everyone this is my first post on this board. I am a junior studying electrical engineering and now we are starting to get assigned projects to start building. I am in the EE lab course but we only deal with simple circuits and low power supply. My first project that I will be building is an audio power amplifier using a TDA2030 IC. My question is can I use a laptop transformer as my power supply? The transformer out puts 18v at 3 amps. This is not going to be the permanent power supply but I want to use it just to demonstrate the circuit to my class. I don't want to spend too much time building a power circuit because I want to spend most of my time analyzing the amplifier circuit and I'm not familiar with power circuits yet.

These are the two circuits that I was looking forward to building. Which one seems like a better candidate?

TDA2030 bridged 35w amp:

TDA2030 amplifier schematic

TDA2030 single chip 40watt amp:

40 Watt Power Amplifier Circuit With TDA2030 – Free Electronic Circuit Schematics
 
I found a bridged amplifier from the spec sheet. Since I do not know who designed the other circuits this is the one I'm leaning towards. I am ordering my parts from mouser and will be purchasing a couple of other chips for future projects. So far I am going to order a few TDA2030 TDA2050 and TDA2003 IC's. I am really into audio amps and was wondering if anyone has any suggestion of car audio IC's that would make a good side project to work on. Also I posted that I don't want to really build a power circuit but after reading some more seems like I just might have to. I just don't like messing with things that can be potentially dangerous until I fully understand them. But I will take extra caution building this transformer. I found some transformers on mouser but dont know which one is suitable.

Transformers:

Transformers

Figure 16--Bridged amp

http://www.st.com/stonline/books/pdf/docs/1459.pdf
 
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Go with single TDA , if you want more power go with TDA 2050 ,it is same thing with more power.
You cant use laptop psu !!!
To drive TDA 20xx series you need a simetrical votage supply,like 2 x 15 volts.I mean you need a +15v and -15v to drive amps.
Laptop psu have omly +18v.
Generaly you need common usage transformer with 2 output woltage betwen 14-18v (2 x 14-18v) with 50 to 70 watts (total).
One rectifier bridge (40v ;4 or 6A),2 x 3300mf or 4400mf 35v capacitors
for basic power supply a both TDA's (stereo).
TDA 2030 real power is 10-12 watt at 4ohm its sound very good.
Dont bother with power rating of any amps,go for how its sounds !!
TDA is a good for start...
 

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Well...:rolleyes: I didn't find it in a kit ....it was in the middle of a Tv PCB and all I had to do was to cut the square containing the circuit and put it in a box
with a 20V trasformer ( unloaded ), a diode bridge and a pair of 2200 uF capacitors .:p
It has enough punch and it drives low loads.
 
I think he looks for kit amp (with all parts in plastic bag).


No I am not looking for kit amps and yes I am just a beginner but I am trying to learn how to build different audio amps. I don't want an amp that is to easy to build because there will be no way to physically see whats changing inside the IC and I want to know how the signal is changing. I have access to lab equipment and I want actually understand whats going on at different stages of the circuit. I am starting off with IC's because there is less hassle and I have a time constraint since its a school project. But eventually I would like to build a simple low power amp with single transistors and thoroughly analyze the circuit. I am doing all the audio stuff as a hobby aside from my school work. We really haven't touched on high power amps yet just small signals and I would like to know more about power amps. Thanks for all the information. Also I realized last night after I cut the tip off the laptop transformer that it was 18VDC since there was only one thick wind of wires.
 
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I wouldn't trust too much in electronic PSUs for audio amplifiers .
They're too much complicated and the simpleness of a bobbin as in a transformers is great . Another matter is pro audio ,where low weight & high power make the difference -check out the latest PFC circuitry adopted :rolleyes: -
If the thread started from ICs and it's moving to discretes , I would be happy !:)
 
If you want to use the laptop PSU to keep the cost down, just order the TDA2050. The others will work, but you can order a few and use them for higher power amps later. It can be wired into single supply mode just like the other chips. Output will be much reduced at 18 volts as they are meant to be operated on split supplies of 36-45 volts (total) to reach 20 plus watts. Since this is your first project, don't forget to use a heatsink with the IC.

You can explain a lot about what is going on with the amp. understanding the negative feedback loop can earn you an A on the project. I doubt they expect you to build a discreet amp.
 
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Yes johnr66 is right the main reason why I wanted to use the laptop PSU was to keep the cost down. I really don't want to have to spend $40 dollars on a transformer right now even though I know later on I know I will need on. As far as the negative feed back loop goes from what I remember it was used to compensate for push-pull distortion. But I haven't even start to look inside the IC yet. In lab we used the negative feedback to fix distortion and from my understading R3 is connected at the output so the whole amp is compensated. Also I know 9 volt batteries will not be able to supply this circuit for a long time because they are not made to put out much amps but would two 9V batteries be able to power the circuit and speaker for about a minute? I only need to demonstrate for a couple of seconds.
 
Yes ,copper price has risen a lot ,and nowadays transformers cost has doubled in respect to 10 years ago . But you didn't specify which power . For 50 W I think you can spend 30$ ,or you may look at some dumpster where old tvs ,radios etc lay unused ,with broken electronics but with functioning transformers .
:)
 
-picowallspeaker- is absolitly right,man with expirience may help a lot.
A psu transformator for you neds is about 10-20$ an other components for psu is less then 20$ (not near 400$).
Dont improvize be a pro,you education is to be a pro,its cost you a few $ more in that case.
Man with no expirience make a bad improvisation.
Audio tehics is a expensive job while you learning or making things ,see another topics on this forym.
Only thigs we try to ,is to help you. ....no to play gods.
 
2pcs 9v wont drive TDA 20xx ,because you stil need a negative voltage for amp
If you loking for single voltage (asimetrical) psu IC's .use TBA 800 or similar.
They will work with laptop psu,no need for pre-amplification,TBA 800 has a detector level signal input - I mean you may plugin enythig directly to his input port mp3 players, i pods and will play.
Its low-cost amp with very good audio reproduction,simply to build,and is posible to find in kit form.Yes you need KIT because you want spend a reasonbly low amounth of money.And you want to chase a parts for amp.
I think it is a cheapest and simimplyes way to build a amp yourself.
You need 30 min to build that with minimal expirience,and they work on 9v batt. for not to long (2pcs 9v in parallel work longer,in serial work louder).
 
I disagree with the last posts. Build the amp for single supply mode and use the laptop brick. Save the money for a real transformer and PS components for later. As a beginner, it is unnecessary and not desirable to take on too much on your first outing.

The TDA2050's internal bias comes on at under 3 volts, so no problem using a 9 volt battery in single supply mode, or two for split supply mode. One for the + rail, one for the - rail. You would be better served using 8 AA cells in split supply mode (4 per rail) since the quiescent current draw will drain 9 volt batteries in a few hours (and playing music in a few minutes).

If you mean "push-pull distortion" being cross over distortion, no that is not what negative feedback is for. Read the Wiki article on NF. Cross over distortion is taken care of by turning the transistors on with a small bias current. Also check Wiki on that too.
 
I am bought the components for both the single supply amp and split supply amp. I think I will demonstrate the single supply amp in class and make a videos of the split supply amp because in lab we have a couple of elvis boards that have split power supply that I can use to power the amp. I will only have to explain how one works so I will do more research once they are built. I guess I wasn't clear on my answer to the negative feedback and I meant when we used negative the negative feedback it was for a push-pull amp and the feedback helped smooth the signal out. As of right now I am just worried about getting the amp to work and this weekend I will begin to analyze.

I disagree with the last posts. Build the amp for single supply mode and use the laptop brick. Save the money for a real transformer and PS components for later. As a beginner, it is unnecessary and not desirable to take on too much on your first outing.

The TDA2050's internal bias comes on at under 3 volts, so no problem using a 9 volt battery in single supply mode, or two for split supply mode. One for the + rail, one for the - rail. You would be better served using 8 AA cells in split supply mode (4 per rail) since the quiescent current draw will drain 9 volt batteries in a few hours (and playing music in a few minutes).

If you mean "push-pull distortion" being cross over distortion, no that is not what negative feedback is for. Read the Wiki article on NF. Cross over distortion is taken care of by turning the transistors on with a small bias current. Also check Wiki on that too.
 
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