Hello,

I am first year, electrical engineering student and I am trying to create a simple amplifier for a 20watt/8ohm speaker. I want to assemble the circuit from this page : https://www.electro-tech-online.com/threads/20-watt-power-amplifier.45/
but how can I be sure that it is going to work?

Thanks for your time, appreciate your help.

 

I would advise you to not use a breadboard, but a soldered proto board instead.

 

I would advise you to not use a breadboard, but a soldered proto board instead.

Thanks for your reply. I will use a soldered proto board then. Is there any way to know that it will surely work ?

 

You just might try modeling it in LTSpice first to see what happens? When I breadboard an amp (yeah I know) I like to use small multiturn pots to "tweak" with to try and optimize the waveform on the scope. YMMV Then you can protoboard the results.

 

I would imaging it will work.
get yourself a copy of the data sheet and see how their application example compares.
Keep the leads short and have the bypass caps as close to the IC as you can.

 

The schematic you copied will not work because its pin numbers are wrong. It says 20W into a 2 ohm speaker but 2 ohms will seriously overload it, look at its datasheet.

The datasheet does not mention your 8 ohm speaker, it says 20W at high distortion into a 4 ohm speaker when the supply is 14.4V. It might produce 12W at high distortion into 8 ohms.

If you build it on a breadboard then its pins will not fit and how will you cool it? A heatsink also will not fit.

Buy is soon because of 3 versions that Digikey had they say that 2 versions are obsolete and they have no stock. They still have some "R" version in stock but the datasheet does not say what is R (something is reversed?).

 

The schematic you copied will not work because its pin numbers are wrong. It says 20W into a 2 ohm speaker but 2 ohms will seriously overload it, look at its datasheet.

The datasheet does not mention your 8 ohm speaker, it says 20W at high distortion into a 4 ohm speaker when the supply is 14.4V. It might produce 12W at high distortion into 8 ohms.

If you build it on a breadboard then its pins will not fit and how will you cool it? A heatsink also will not fit.

Buy is soon because of 3 versions that Digikey had they say that 2 versions are obsolete and they have no stock. They still have some "R" version in stock but the datasheet does not say what is R (something is reversed?).

Thanks for your reply ! I will keep that in mind !

 

I would imaging it will work.
get yourself a copy of the data sheet and see how their application example compares.
Keep the leads short and have the bypass caps as close to the IC as you can.

Thanks for your help

 

You just might try modeling it in LTSpice first to see what happens? When I breadboard an amp (yeah I know) I like to use small multiturn pots to "tweak" with to try and optimize the waveform on the scope. YMMV Then you can protoboard the results.

LTSpice sounds good, I will give it a try, thank you !

 

I doubt that LTspice can simulate the antique TDA2005 amplifier IC properly, because an accurate model is probably not available.
Instead, simply build it as shown on its datasheet.

 

If you're simulating and building an amp for a school assignment, something with discrete transistors might be a better choice. For example, John Linsley-Hood's 10 watt class-A amplifier, which has just 4 transistors per channel in its simplest form. (But class-A means it uses a lot of power and will need a massive power supply and heat sinks).
https://sound-au.com/tcaas/index-1.htm
Or Reg Williamson's amplifier which has an extravagant 6 transistors.
https://www.diyaudio.com/forums/solid-state/187928-picking-ss-williamson-amp-worth-moding.html

 

He is not learning about amplifier circuits, instead he is learning about buying a few parts and hooking them together in a mess on a breadboard.