Build an Audio amplifier. - Page 1
Forum section: electronics / beginners

author: Nexo
author_rank: Regular Contributor
timestamp: March 19, 2017, 06:11:11 pm
content: Hello everyone!I have this project in mind and is about building an Audio amplifier because I have two 8 ohms, 5 volts speakers and no way to use them unless I build this Amplifier.I've found a simple one that uses the IC TA8210, here is the PDF. Note: Is in Spanish but I think the most important part is the schematic.http://construyasuvideorockola.com/downloads/ta8210_flat.pdfIs a 24W (8 Ohms) stereo amplifier and uses using a BTL configuration.1. The next picture shows the input signal and with this comes my first question:http://construyasuvideorockola.com/imagenes/amp_40w/amp_40w_04.jpgIn this pic we have a 3 pin connector distributed as follows:Left pin: Left signal inputRight pin: Right signal inputMiddle ping: GroundIf I want to play music from my laptop's or phone's jack, using a male-to-male connector, how could I be able to separate the signal that comes out of the jack into a right and left one?What I think might be the answer but I'm not sure: The 4.5 mm Audio connector is divided in 2 sections (3 if we have a microphone, right?) so I could separate strip the cables on the other end of the 4.5 connector and trial and error my left and right output signal on connect those to the respective pins.2. The circuit's heart is the IC TA8210. I've bought almost all components for this project, and for the power supply as well, but I wasn't able to find this IC and I would have to wait at least 1 month if I buy it from China which is a deal-breaker. Luckily, I hope, I happen to have another IC which was is a broken mini component and is the D8207.My question is, can I use this IC instead of the TA8210? And, if so, what changes would I have to make in order to accomplish this?D8207's datasheet:http://www.datasheet4u.com/datasheet-pdf/Silicore/D8207/pdf.php?id=939378TA8210's datasheet:http://pdf1.alldatasheet.com/datasheet-pdf/view/31449/TOSHIBA/TA8210.html3. This broken mini component also has a transformer rated at 2 Amps but this project uses a 4 Amps transformer.What would change if I used this 2 Amps transformer? Would this project work or the volume would be too low?Info the appears in the transforme I have: EI - 25*25 220V/110V 2A-145Also, as you can see, this transformer works with 220V/110V and it has some weird connections with a switch allowing the user to choose whether it will work with 220V or 110V, do you know where can I read about it in order to understand the connections?Thanks in advance!I'm really looking forward to build this project and learn a lot

author: Audioguru
author_rank: Super Contributor
timestamp: March 19, 2017, 11:46:44 pm
content: Speakers are not rated in volts like you said, "8 ohms, 5 volts". A speaker with a built-in amplifier can be made for a pc and be powered from 5V but its output power and loudness will be very low.Instead, are your speakers little and are rated at 8 ohms, 5W?You show datasheets for two amplifiers. The Toshiba TA8210 English datasheet says it is a car radio amplifier designed to have a 13.2V supply and 4 ohm speakers for an output power of about 11W per channel at low distortion or 19W per channel at horribly high distortion. The datasheet does not show 8 ohm speakers so you must guess what the output power will be.The datasheet for the low power D8207 is a terrible translation from Chinese. It looks like it is designed to have a 9V or 12V supply. With a 12V supply its output power into a 4 ohm load is 4.6W per channel with horribly high distortion and will be less with lower distortion. It makes a completely different amplifier using different parts from the TA8210 amplifier.You show a photo of 3 pins on a pcb but you do not say what it is from.You talk about a power transformer but your description of its specifications is not clear. If it has two 25VAC outputs then in series they make 50VAC which is too high and in parallel they make 12.5VAC that is also too high and we do not know if your electricity is 110VAC or 220VAC.2A of current is only 1A for each stereo channel. About half the current will make heat so only 0.5A is available for audio. 0.5A squared x 8 ohms is a power output of only 2W per channel and the amplifier power supply must be about 14VDC that you do not have.

author: Nexo
author_rank: Regular Contributor
timestamp: March 20, 2017, 01:03:34 am
content: QuoteMy bad, I saw a "V" instead of "W". Here I show you some photos of the speakers I have. In one "box" there are 2 speakers, a little one and a bigger one, I think is the base and treble, right?http://prntscr.com/em20dyhttp://prntscr.com/em20mohttp://prntscr.com/em20q8The "bigger circle" has the following info: "JY 4 ohms, 8 W"And the "smaller circle" has this: "JY 8 ohms, 5 W"Note: Sorry for the lack of better words to describe what I want to tell. English is not my first language.QuoteAs I stated in my first post, I'm using the schematics and info that I found online:http://construyasuvideorockola.comThey have several Audio projects and what I said is based on what I've read there.QuoteI wasn't able to find a better datasheet.So I HAVE to get the TA8210, right?Or could I just use the circuit that was inside the mini component? Here are some pics:PCB in which is the D8207:http://prntscr.com/em1ww4}Closer look:http://prntscr.com/em1x81Or at least, could I "desolder" (Idk if that's the right word for it) the part of the audio amplifier and create a new circuit on Proteus or Eagle.QuoteI did say it but I guess I wasn't too clear. The signal coming out of the computer goes into the amplifier circuit through this pin based on this:Left pin: Left signal inputRight pin: Right signal inputMiddle ping: GroundQuoteI have some pics here:http://prntscr.com/em1z38http://prntscr.com/em1zmihttp://prntscr.com/em1ztgThank you for your reply!

author: Marinated
author_rank: Contributor
timestamp: March 20, 2017, 01:59:15 am
content: Sorry, but sourcing the TA8210 from China doesn't sound promising. Finding genuine Toshiba parts, especially older parts, is many times more difficult than finding fakes. Toshiba parts are notoriously, prolifically faked.If you are interested in building audio amplifiers, take a look at Rod Elliott's website. He is highly respected and long established in this field, and there are many excellent projects you can try. They are very well documented, and being a good engineer, he doesn't have a habit of specing out-of-the-way parts that won't be available in a few years' time.

author: Audioguru
author_rank: Super Contributor
timestamp: March 20, 2017, 03:37:17 am
content: Picking old parts at random without any planning is not how I do things. If I want an audio amplifier I select a modern IC that has a complete datasheet with a recommended schematic and pcb design and I order it. It is delivered the next morning.If I need a transformer I calculate what I need then look at the distributor's website and order one.

author: Nexo
author_rank: Regular Contributor
timestamp: March 20, 2017, 03:40:33 am
content: Quote from: Audioguru on March 20, 2017, 03:37:17 amNot every country has that, some of us have to make things with what you have and not always with what you want. Thanks anyway.

author: rdl
author_rank: Super Contributor
timestamp: March 20, 2017, 05:08:46 am
content: Rod Elliott's site is here:http://sound.whsites.net/index2.html

author: Nexo
author_rank: Regular Contributor
timestamp: March 20, 2017, 06:48:05 am
content: I don't really want to learn to code in Arduino right now, I want to learn about op amps, amplifiers, transistors... Could you recommend a site, videos or books in which I could learn the theory as well as the practical side of these topics?Thanks in advance!

author: mariush
author_rank: Super Contributor
timestamp: March 20, 2017, 07:14:31 am
content: Your transformer looks like it has 3 wires coming out on the primary side, and 4 wires coming out on the secondary side.The secondary side is easy : you have two separate windings, and each could have a different voltage and different amount of current (voltage x current = number of watts that winding can provide).The primary side is a bit tricky, since you have only three wires.I think this transformer is either designed for 110v or for 230v. but the extra wire is there to give you the choice to use this transformer in countries that have slightly different voltage.For example, the first wire would be 0v, the second wire could be 100v and the third wire could be 115v - so if you're in a country like Japan where they have 100v AC , you would connect the mains wires between 0v and 100v , and if you're in US or a country with 110-120v you would connect the second mains wire to that wire, leaving the middle wire unconnected.It could also be a transformer designed to work with 110v or 220v, in which case the middle wire would be in the middle of the primary winding. In this case, on 110v you would connect the first and last wire to use 110v with all the wire of the primary winding, and if you're on 220v you'd connect the first wire and the middle wire, using just half of the wire in the primary winding.This is not how it's normally done, normally such transformers have two separate primary windings like you have on the primary side , and if you have 220v you connect the windings in series, and if you have 110v you connect the windings in parallel (so the same amount of wire is used in both cases)Based on the text on the transformer, it's probably a 25VA transformer. If the secondary windings are equal (same voltage , same current) and what I assume is true, that means each of those windings can provide up to 12VA to something connected to that winding.This VA is an AC unit of measure .. basically, if the secondary winding is 12v AC and you have an incandescent lightbulb rated for 12w, it means the lightbulb will work perfectly and be as bright as it was designed.Electronics don't work with AC voltages however, so these voltages have to be converted to DC. That's what those groups of 4 diodes do on the circuit board you shown us ( here :http://prnt.sc/em1z38) and the large capacitor after those four diodes convert the 12v AC voltage to a voltage that's probably around 10-12v DC (depends on the size of that capacitor).In the picture, I see a LM7808V chip, which is a linear regulator that outputs 8v as long as the input voltage is at least 9-9.5v, so that tells me at least one of those windings is big enough that after converting the AC voltage to DC, you still have about 9-10v DC.But, this conversion from AC to DC isn't without losses, so if you have 12v AC and about 12VA on the secondary winding initially, after this conversion you have maybe 10-12v DC but only about 7.5-8VA (8 watts at 10-12v DC)So if your audio amplifier needs at least 12v or something like that, this transformer may not be adequate for you, in some conditions the DC voltage may be too low for the transformer to work.No, you can't replace an audio amplifier chip with another, they're different inside and require different components.If it was up to me, considering you're a beginner, I'd suggest going and buying a couple of TDA2050 chips and the components in the schematics in the datasheet .. they are pretty easy to use and require few components and they can be made to work with either positive and negative voltage up to +/- 25v or with a single power supply ( up to 50v) and the datasheet has a schematic inside for both versions of power supply, and the chips are also super easy to find on eBay (you can buy 2 for 1.2$ , 10 for 3.3$ or 50 for 12$).Here's the datasheet:http://www.st.com/content/ccc/resource/technical/document/datasheet/1d/71/14/1e/5d/cf/47/01/CD00000131.pdf/files/CD00000131.pdf/jcr:content/translations/en.CD00000131.pdfHave a look at the example circuit board for split power supply on page 4 , or the single power supply on page 6 ... in your case, i'd connect the secondary windings in series and create a single power supply and feed both amplifiers from it.THis is a MONO amplifier, so you need two identical circuits for each channel, so you have to buy 2 of each you decide on. and later when you find a more powerful transformer you can simply replace it (the parts accept up to 50v DC like I said).Here's a couple more circuits that may be even simpler than the ones inside the datasheet :http://www.eleccircuit.com/tda2050-amplifier-stereo-35w-75w/And here's another design with split power supply (connect the secondary windings together and the middle becomes ground, and the ends become V- and V+) :http://diyaudioprojects.com/Chip/DIY-TDA2050-Hi-Fi-Chip-Amplifier/It's a very good chip to start designing something.ps. and most components (like resistors) are standard values which you'd probably find in other circuit boards you have around (tvs, old radios etc , broken computers). You could grab a multimeter, desolder components and measure the values and you'll build yourself a nice collection of basic parts and then order only what you need.

author: Richard Crowley
author_rank: Super Contributor
timestamp: March 20, 2017, 07:14:45 am
content: Quote from: Nexo on March 19, 2017, 06:11:11 pmBeware that is an obsolete chip and you have diminishing chances of finding a genuine chip.There are more modern solutions here in 2017 using "Class-T" chips like TA2024You can buy kits or entire assembled and tested boards with this chip for less cost than finding the components yourself. And they come with a very nice special-made PC board. There are dozens of these on Ebay.And if you want a more traditional analog solution, there are also dozens of amplifiers on Ebay made with TA2020.QuoteThe 3.5mm output from your computer has 3 sections, commonly called "Tip", "Ring" and "Sleeve" ("TRS") The LEFT audio comes from the "TIP", the RIGHT channel audio comes from the "RING", and the common/ground is the "SLEEVE". If the 3.5mm connector also has the connection for the microphone, then it has FOUR sections.QuoteThe D8207 is quite a different kind of chip from the TA8210. You can see from the reference circuit diagram in the data sheet what the differences are. It appears that your D8207 is also obsolete and you very well may encounter delays, high prices, and danger of counterfeit because of its age and status.Stongly suggest looking at current, modern ICs that are still in production. Your source of circuits seems very old to be suggesting such old chips.QuoteYou really would be much better off buying a KIT from Ebay. It will teach you just as much, perhaps MORE than trying to source all the components yourself and make the circuit with no PC board.

author: Nexo
author_rank: Regular Contributor
timestamp: March 20, 2017, 08:00:47 am
content: Last 2 replies really helped me a lot! Thank you very much to all who've replied to this thread.Just two more question: The kit you are referring to is a PCB+parts which I can solder or it comes ready to use? I'd really like to practice soldering but I can't find that kind of kit. Could you help me out, please?About the speakers, which circuit could I build in order to have a good audio system based on the speakers I've shown and where can I learn the basics of amplifiers and speakers?All I've studied in college is basic electronics and I'll start studying circuit analysis the next semester, meanwhile I want to learn as much as I can about this subject.Again, thank you very much!

author: Richard Crowley
author_rank: Super Contributor
timestamp: March 20, 2017, 02:11:52 pm
content: Quote from: Nexo on March 20, 2017, 08:00:47 amHere are some examples:http://www.ebay.com/itm/152395381449http://www.ebay.com/itm/292048021445http://www.ebay.com/itm/122405712552QuoteAny of those small amplifiers around 5W up to 20W would work great with those speakers.QuoteSince you appear to have access to the the internet, there is much more information available here than you can possibly read in the rest of your life. And forums like this (and special audio forums) are available for you to ask questions about what you don't understand.

author: Audioguru
author_rank: Super Contributor
timestamp: March 20, 2017, 02:50:27 pm
content: The Chinese amplifier ads have no audio specifications like distortion at a certain output power, noise or how flat is the frequency response.One amplifier uses a 24VA transformer but the output of the amplifier is rated at 15W + 15W (plus the heating of about 20W)= 50W from the 24VA overloaded transformer.Wait a minute. The ad says the transformer is only 12VAC that when rectified and filtered produces 15VDC that is so low that the output power will be very low.The datasheet for the TDA2030A IC shows very low output power when the supply voltage is much more at 24VDC than the 15VDC in this kit and 15W is produced into an 8 ohm speaker when the supply voltage is 37VDC. I wonder if the TDA2030A is a real one, a fake one or a poor copy of one?

author: Richard Crowley
author_rank: Super Contributor
timestamp: March 20, 2017, 03:00:55 pm
content: Quote from: Audioguru on March 20, 2017, 02:50:27 pmAnd neither do the speakers.I GUARANTEE that the amplifiers have an infinitesimal FRACTION of the distortion and frequency variation of ANY speaker. And especially those cheap low-end consumer boxes.QuoteHow much power do you think those speakers willneedto provide nominal sound levels? How much power do you want to put into a driver clearly labeled "8W"?

author: Audioguru
author_rank: Super Contributor
timestamp: March 20, 2017, 04:06:42 pm
content: I was saying that the Chinese ad says 15W + 15W because that is what two ICs are capable of doing, not what their kit can do.The Chinese will probably sell a 12V/20A transformer for the kit then say the audio output from the amplifier will be 240W.I am an audio guy. I have made and heard audio systems that have a lot of power, very low distortion and a very flat frequency response. I have also seen and heard crap.I was at the demo of new speakers and they looked big and had high quality. They produced fantastic deep bass and all other frequencies were produced properly. Then two pretty model ladies went to the speakers and removed covers revealing small speakers under the realistic looking covers. I looked for the hidden sub-woofer but there was not one anywhere. I got goose bumps and I think my hair stood up. How did dey doo dat? I wanna doo dat. The same audio company made the sound system for a new concert hall in my city and it sounds awful. The same company is demo'ing a tiny speaker at Costco and it sounds great for its small size. My son bought a Chinese copy of the tiny speaker and it sounds bad and failed after a few days.

author: Richard Crowley
author_rank: Super Contributor
timestamp: March 20, 2017, 04:20:29 pm
content: Quote from: Audioguru on March 20, 2017, 04:06:42 pmOK. What is it about the kit that limits the inherent capabilities of the chip (if any)? What can be done to improve on that? Those are exactly the learning opportunities available to @Nexo by building one of these kits. Much better to study how a MODERN circuit works that uses CURRENT technology than trying to build a circuit from 20 years ago with long-extinct chips.QuoteRight. But nobody here is suggesting that @Nexo take the published "specs" (or marketing twaddle) at face-value. Another valuable learning experience in sussing out the different between the actual published (and effectively guaranteed) specs by the chip-maker vs. the circuit design, component selection vs. the "feature list" on Ebay. You are providing an excellent list of things that @Nexo can learn from this exercise. Thanks.QuoteI am also an audio guy. I have been into audio, electronics, and video for well over 50 years. And I have also seen great stuff and utter rubbish. I must say, however, that the "average" stuff from 2017 beats the "high-end" stuff from 50 (or 40 or 30) years ago.QuoteShould we assume that the presence of the "two pretty model ladies" and the "goose bumps" was only a coincidence?QuoteIf you have ever been involved in a sound system for a large (or even small) venue, you will come to realize that the very best system in the known parts of the galaxy will sound horrible if the space has bad acoustic design. You are completely at the mercy of the architect, the benefactors, and the "decoration committee", none of whom care a whit about acoustics.QuoteWell, that hardly seems surprising, does it?

author: Nexo
author_rank: Regular Contributor
timestamp: March 21, 2017, 01:50:19 am
content: Thank you very much to all of you!I'm going to but one of the kits here shown and I'm going to make an amplifier only using transistors in order to learn what's going on.Again, thank you very much!

author: TheUnnamedNewbie
author_rank: Super Contributor
timestamp: March 21, 2017, 01:10:39 pm
content: If you are really looking to learn analog electronics, it can be usefull to look at the basic building blocks first (and most basic circuits up to pretty high end opamps are really just these building blocks, and then a bunch of crap around them to make them "better").These blocks are things like Class A/AB/B/C output amplifiers, basic one-transitor circuits (Common Base/Emittor/Collector), differential pairs. Include into that the concepts of feedback, and filter circuits and you have pretty much all you need to understand the basics of audio amplifiers.I don't know what level you are already at, but most courses in electronics I know follow about this order:-Concepts of resistance, voltage, current-Ohm's Law-Series/Parallel networks-Voltage and current sources-Kirchhoff's voltage and current laws-Thevinin and Norton equivalentsAt some point along this they tend to add the concepts of Capacitors and Inductors.Ones students get these concepts, they we can start introducing active circuits. Opamps usually go first, as they are simple in an abstract manner (infinite gain, infinite input resistance, zero output resistance). Opamps also allow for an introductoin of the concept of feedback.Then, throw in equivalent circuits for transistors and diodes.This then allows you to go to basic onetransistor circuits:-Common Base, Emittor and Collecor-Differential Pairs-Output stages (Class A, B, C, AB)Now, I'm not gonna claim that you need to know all of these, but it might be usefull to at least have a look at the basic concepts of linear circuits, and recognise the basic blocks. You don't need an in-depth IC designers understanding of them, but just recognising them will allow you to look at circuits in a different way, and know when to dig deeper.

author: Nexo
author_rank: Regular Contributor
timestamp: March 21, 2017, 01:18:15 pm
content: Quote from: TheUnnamedNewbie on March 21, 2017, 01:10:39 pmYou're completely right and that's what I'm going to do right away and in order to do that I've open another thread asking for the best book, in someone's opinion, recommendation:https://www.eevblog.com/forum/beginners/which-book-would-you-recommend/I hope you can help me there!Thank you very much.