TDA2003  - Page 1
Forum section: electronics / projects

author: meerweten
author_rank: Contributor
timestamp: May 24, 2012, 02:07:58 pm
content: hi everyone,for a school project i need to build a amplifier.specifications:minimum 3Wso after some searching i found that the TDA is a realy good amp for this so i build this on a board but i get a lot of oscilation,does anyone know what i can do to solve this?link to shematicMeerweten

author: Tube_Dude
author_rank: Regular Contributor
timestamp: May 24, 2012, 02:28:24 pm
content: HiHave you used, as in the datasheet, a 100uF electrolytic in parallel woth C1 (100 nF) capacitor?

author: ejeffrey
author_rank: Super Contributor
timestamp: May 24, 2012, 02:29:32 pm
content: Well, your schematic is the same as the data sheet reference schematic but missing the large power supply capacitor. Try adding that. High gain, high power amplifiers are sensitive to layout. Make sure that the output can't capacitively couple back to the input and that the speaker return signal has a good path directly back to the supply capacitor. Are you building this on a PCB, perfboard, or solderless breadboard? If you are using solderless breadboard ditch it for perfboard or an etched PCB.

author: meerweten
author_rank: Contributor
timestamp: May 24, 2012, 02:30:29 pm
content: yes i added the additional 100µ as in the datasheet is told,i also splited ground in 1 just conecting on the ampbuilded on pcb, test on bread went well without oscilation :p:d

author: free_electron
author_rank: Super Contributor
timestamp: May 24, 2012, 02:36:56 pm
content: If it worked on perfboard but not on pcb then there are two possibilities :You have coupling between in and out. This can happen if the input trace runs close to the outputIf you etched the board yourself it is possible you have a high-ohms leakage somewhere .. Like a piece of copper that has not fully etched through.Show a picture of the pcb.Other possibilities : flux .. Depending on you solder skills you may have a blob of carbonized flux somewhere that creates a resistive path. Clean your pcb ....

author: meerweten
author_rank: Contributor
timestamp: May 24, 2012, 02:38:30 pm
content: i missed in my last post, i tested it at a breadboard and it worked:p not perf!

author: mariush
author_rank: Super Contributor
timestamp: May 24, 2012, 02:45:50 pm
content: I'd suggest going with a TDA 2050:http://www.st.com/internet/com/TECHNICAL_RESOURCES/TECHNICAL_LITERATURE/DATASHEET/CD00000131.pdfIt's about 3$ a chip and page 6 shows a circuit with single power supply, and very easy to do on a breadboard or even one of those boards with lots of holes.It can do at least 5 watts @ 8ohm on +/- 10v (or 20v single supply) so you can use one of those laptop adapters to run it. With 12v from a regular computer power supply, it can do about 2-3 watts at 8 ohm.

author: bilko
author_rank: Frequent Contributor
timestamp: May 24, 2012, 03:23:47 pm
content: Have you checked the components are correct, especially that you haven't swapped R2 and R3 ?

author: meerweten
author_rank: Contributor
timestamp: May 24, 2012, 03:25:14 pm
content: yes thats the first thing i did :p

author: MartinX
author_rank: Regular Contributor
timestamp: May 24, 2012, 04:55:26 pm
content: I have tried to build amplifiers using TDA2003 in the mid eighties, it was a pretty old chip then and it is a living fossil now. I had stability problems also, this thing oscillates whenever it feels like it which is almost always. The suggestion from mariush to use TDA2050 is a good one, TDA 2030, 2040 and 2050 are more modern and much more stable and easier to work with. I finally built an amplifier using TDA2030 that worked really well in 1987 and I continued to use it until 2010.

author: meerweten
author_rank: Contributor
timestamp: May 25, 2012, 12:31:25 pm
content: got it working after all, i change the value of the 100µF to 330µF