How to Design and Build a TDA2050 Stereo Amplifier

you hey there welcome to another circuit basics tutorial this video I'm going to show you the stereo amplifier I built with the TDA 2050 chip amp first we'll take a look at the schematic and I'll explain what each of the components do then we'll look at the PCB I designed and I'll show you some things to keep in mind when you're designing an amplifier PCB at the end of the video I'll wire up the amp and play some music so you can get an idea of what it sounds like to keep this video at a reasonable length I had to leave out some details but I have a complete tutorial on the circuit basics blog with all the schematics PCB layout formulas wiring diagrams and a much more in-depth explanation of what I'll be talking about today I'll link to that in the description so be sure to check it out after the video ok now let's take a look at the schematic and I'll explain what each of the components do I used ez EDA to draw the schematic so let me pull that up here in the full tutorial I put links to the schematic and PCB project files so you can edit them if you want to I already have an account set up so I'll just log in here okay now go up here and click on my projects this is a list of all my projects we've made tutorials and videos for all these amplifiers so if you're interested search for them on the blog or on our YouTube channel here's the TDA 2050 project there's the schematic and the PCB I'll talk about the PCB later but now let's look at the schematic clicking open and editor will open the schematic in the schematic editor this is where you can make any changes to the file but let's export this as a PDF to get a better look at it you you can also export it as a JPEG or SVG image okay so here's the schematic the schematic is just for one channel so if you're building a stereo amplifier you'll just need to order two of everything here I'll start by explaining the input and output terminals this right here is the positive line of the audio input signal the audio input ground isn't included in the schematic because it's wired directly to the main system ground I'll explain more about that later though this is the signal ground it's the ground for all the low current components in the circuit and here's the power ground terminal it's important to keep the signal ground and power ground separate to reduce the chance for home I explained all about that in the article so definitely read that if you want to know more this is the negative voltage supply terminal here's the positive voltage supply terminal here's the positive line of the audio output this will connect to one of the positive speaker wires the speaker ground wire connects to the main system ground also so it's not shown on the schematic either and now let's talk about the different components in the circuit the gain of the amplifier is set by resistors r4 and r5 you can calculate the gain with this formula right here that will tell you the voltage gain you'll get with given values of r4 and r5 if you want to set the gain to a different level you can rearrange the formula to solve for the resistance of r4 or r5 these are the input pins of the TDA 2050 the pin on top is the non-inverting input and the pin on the bottom is the inverting input when the amp is playing the current flows to each of these pins any difference between these two currents will be amplified as noise so it's important to make sure that these currents are as close as possible to each other this is called balancing the input bias current the non-inverting input sees the resistance of r2 plus r3 and the inverting input sees the resistance of r5 all we need to do is set the resistance of r2 plus r3 equal to r5 here r2 plus r3 equals 22 kilo ohms and r5 is 22 kilo ohms so the current should be balanced the app has several resistor capacitor filters that set the upper and lower frequencies of the amplifiers bandwidth one filter is here at the input with c1 + r2 this is a high-pass filter the frequency at which the filter starts to work is called the cutoff frequency or F sub C F sub C can be calculated with this formula resistances and ohms and capacitances and farads another high-pass filter is located here in the feedback loop with r4 and c3 you can use the FC formula here to to find the cutoff frequency the third filter is a low-pass filter at the input formed by r1 r3 and c2 this filter sets the upper frequency of the amps bandwidth and also filters any radio interference picked up by the audio input cables to calculate the cutoff frequency use the FC equation with r1 + r3 for the resistance and c2 as the capacitance in the full tutorial I explained how I came up with the cutoff frequencies and values of these components but if you want to change the cutoff frequency of any of these filters you can rearrange this formula to solve for the component value at a particular FC r6 and c-4 form the Sobel network the Zobel network is used to prevent oscillation caused by the inductance of the speaker wires and speaker driver it also filters out any radio frequencies picked up by the speaker riders you can use the COFF frequency formula again to find the frequency where radio interference is cut this amp has two sets of power supply decoupling capacitors to filter noise from the power supply and provide a supply of reserved current to the amplifier capacitors C 5 C 7 and C 10 are the decoupling capacitors for the positive voltage pin capacitor c6 c8 and c9 are the decoupling capacitors for the negative voltage pin okay that's pretty much everything on the schematic now let's have a look at the PCB layout if you're using easy EDA you can access your project files over here in this drop down menu click on my projects and you'll get a list of all your project files here's my TDA 2050 project this is the schematic file and this is the PCB file this PCB is just one channel so if you're making a stereo amplifier you'll need to build two of these and if you want to edit any of these footprints or reroute some traces you can get the links to this file in the full tutorial I won't be doing any editing in this video I just want to talk about the design principles I use to layout the PCB I could use the PCB editor to show you the layout you can turn on and off each layer here but there's actually a better way it's easy EDA is Gerber file viewer to access it go up here to the fabrication output button this is also where you can order the PCB you can specify how many layers your PCB has set the order quantity PCB thickness PCB color surface finish copper wait and substrate material you can also download the Gerber files if you want to etch the PCB yourself but for now we just want to look at the PCB so I'll open up the Gerber viewer okay here's the PCB over here on the left are the different Gerber files you can toggle them on or off this view is a good way to see if any of your traces or through holes are too close together you can also look at the bottom layer we'll see that later but now let's check out the top layer let me just zoom in a little bit here all right so here's the footprint for the TDA 2050 it's right up against the edge of the PCB so the PCB won't get in the way when you attach a heatsink here's the terminal for the positive audio input all of the terminal footprints are four quarter inch Spade terminals if you want to use another type it's easy to change the footprints in the PCB editor here's the terminal for the signal ground it connects to the signal ground plane on the bottom of the PCB here's the positive supply voltage terminal here's the negative supply voltage terminal this is the terminal for the power ground they connects to the power ground plane on the bottom and here's the terminal for the audio output there are three power supplied decoupling capacitors for the positive voltage supply notice that their place as close as possible to the positive voltage pin of the TDA 2050 that's to reduce parasitic inductance and resistance in the tracks leading to the power pin as much as possible I also made the traces to both power supply pins really wide to maximize current flow here's the power supply decoupling capacitors for the negative voltage power rail they're also placed as close as possible to the TDA 2050s negative voltage pin and this is the big input capacitor c1 one of the most important things to keep in mind when designing an amplifier PCB is to keep high current parts of the circuit away from low current parts large electrical currents will generate a magnetic field that can create currents in the low current traces that will cause a voltage to form at the amps input which will be amplified as noise to keep them separated as much as possible I placed all of the low current input and feedback loop components on the left side of the PCB and all of the high current power supply and output components on the right side now let's check out the bottom layer I've used two ground planes on the bottom layer one for the low current components and one for the high current components the purpose of using a ground plane is to minimize loops between traces which reduces the chance that they will transmit or receive electromagnetic interference keeping the ground planes isolated like this prevents high currents from flowing through the low current input and feedback circuits here's the TDA 2050 this is where the terminal for the power ground connects to the power ground plane this is where the negative terminals of the positive power supply decoupling capacitors connect to the power ground this is where the positive terminals of the negative power supply capacitors connect to the power ground this is where capacitors c4 of the Zobel network connects to the power ground this is the signal ground terminal here's where capacitor c3 of the feedback loop filter connects to the signal ground plane resistor r2 of the input high pass filter connects to the signal ground plane right here and this is where c2 of the input low pass filter connects to the signal ground plane alright that's the PCB now I'll wire up the amp and play some music so you can hear what it sounds like let me close this if you want to order this PCB just click here on save decart before we get started I just have to warn you this project involves using high voltage mains supplies these can seriously injure or even kill you please don't build this project if you don't have the knowledge and training needed to work with mains supply voltages if you're inexperienced find someone with experience to help you okay so here's the PCB I ordered from easy da I ordered five them and the total came to about $22 us with shipping came out really good all the traces are outer precisely the text is really clear I'm really happy with the quality these are the assembled PCBs attached to a heatsink be sure to use thermal paste between the chips and the heatsink if you're attaching both channels to the same heatsink you should also use an isolating pad and washer since the metal tab is connected to the negative supply voltage pin here's the audio output Spade terminal here's the positive voltage terminal a negative voltage terminal and here's the power ground terminal this is the positive audio input terminal and the signal ground terminal this is my transformer it's a 15 volt 225 v8 toroidal this is my power supply and you might be wondering what this light bulbs for it's called a bulb tester and it's supposed to limit the current flowing to the amplifier when you first power it up it's a 60 watt incandescent light bulb wired in series with the hot AC mains wire leading to the transformer if there are any short circuits or something isn't connected properly the light bulb will prevent the mains current from causing damage to the circuit if everything is connected properly the light bulb should light up briefly then fade out after you turn on the amp if there is a short the light bulb will stay on you should definitely use one when you first power up a new power supply or amplifier just Google amplifier bulb tester and you'll find lots of tutorials on how to make one here are the wires for my right speaker here are the wires for the left speaker they're just some cheap six ohm speakers I picked up at a thrift shop I wouldn't recommend hooking up any expensive speakers the first time you test the amplifier since they could get damaged if anything's wrong with the amp this is the earth wire from the main supply in the finished amplifier this will connect to the metal chassis but for this test I'm just going to connect it directly to the earth terminal on the main system ground here's my 3.5 millimeter audio input socket there are three wires one is for the positive left channel input one's for the positive right channel input and ones for the audio input ground these wires will connect the positive and negative supply voltage and power ground to each amplifier I'll use these wires to connect the signal ground of each amp to the main system ground and here's my audio input cable before I start connecting everything let's get a better look at the main system ground this is where all of the amplifiers ground wires will connect I built it into the power supply but yours might be located somewhere else this is the earth terminal and the finished amplifier this will connect to the metal chassis or to a ground loop protection circuit but for this test I'm just going to connect it straight to the mains earth wire these are the negative voltage supply terminals there's one for each channel and these are the positive voltage supply terminals these are the speaker ground terminals here the power ground terminals the signal ground terminals and the audio input ground terminals I'll start by connecting the earth wire from the main supply to the earth terminal on the main system ground now I'll connect the right speaker the ground wire goes to the main system ground and the positive wire goes to the output terminal of the right channel amplifier now I'll do the same for the left speaker the ground wire is going to the main system ground and the positive wire is going to the output terminal on the left channel amplifier next I'll connect the supply voltage and power ground wires to the right channel I'll use the yellow wire for the positive voltage supply one side goes to the V plus terminal lamp and the other side goes to the v+ terminal on the power supply I'll use the red wire for the negative voltage supply so I'll connect one side to the v- terminal on the end and the other side to the v- terminal on the power supply the black wire will connect the power ground so I'll connect one side to the power ground terminal on the main system ground and the other side to the power ground terminal on the amp now I do the same thing for the left channel using the same color wires I did for the right channel V+ on the amp to v+ on the power supply you v- on the amp to v- on the power supply you and power ground on the app to power ground on the main system ground you now connect the audio input plug the black wire is the audio input ground so that connects to the input ground terminal on the main system ground the yellow wire is the positive left channel audio input so that connects to the n plus terminal on the Left channel amp the green wire is the positive right channel input so that connects to the n plus terminal on the right channel okay now I'll connect the signal grounds one wire connects from the signal ground terminal on the right channel amp to one of the signal ground terminals on the main system ground the other wire connects the signal ground terminal on the left channel lamp to the other signal ground terminal on the main system ground okay once you have everything connected it's a good idea to look everything over and make sure it's connected properly this all looks good so I'm going to plug in my audio input cable you I'll plug the power cord into my surge protector and switch it on you see the light bulb flashing on for a moment then go dim that's a good sign if you get a buzzing sound when you touch the input plug that's a good sign that means the amp is working so far now I plug in my audio source and play some music [Music] all right well it's obviously working that sounds pretty good can't hear any Distortion it's got pretty good bass and the mids and highs are pretty clear too bad sounding right you want to touch the heatsink after it's been playing a while to make sure it's not getting too hot if it gets hot after 10 or 15 minutes it means neither your heatsink is too small or there's some oscillation going on after you turn off the amp it'll keep playing until the capacitors on the power supply or drain okay well hopefully this video has made it a little easier for you to build an amp with the TDA 2050 let me know in the comments if you have any questions and be sure to LIKE and subscribe to our channel if you found it useful thanks for watching see you next time

Channel: Circuit Basics

Views: 59,300

Keywords: circuit projects, electronics projects, circuits, circuit basics, diy audio, diy amplifier, diy electronics, tda2050, tda2050 schematic, tda2050 pcb, tda2050 stereo, tda2050 amplifier, tda2050 amp, tda2050 tutorial, tda2050 demonstration, tda2050 gain, tda2050 bandwidth, gainclone, tda2050 gainclone, tda2050 project, how to build a tda2050 amplifier

Id: fmubmoH7lbs

Length: 19min 29sec (1169 seconds)

Published: Wed Feb 22 2017