My original intent for this project was to supply an audio input to feed homemade oscilloscopes,but in reality there are lots of fun things to do with a simple audio amplifier. This project is very "loose" meaning that although I have a nice selection of components and a decent knowledge of how they work......... I'm the hack. At best I have the knowledge and skills to stay safe, even though I mess around with automotive coils and CRT flyback transformers and massive Capacitors.
This project is also "loose" because If I were to give a step by step instruct-able .... chances are you wouldn't be able to find the exact parts that I list but It doesn't matter. This is just a guide. This picture shows a "Cool Cube" . I bought about 15 of them at a Store called "Princess Auto" which I think must be Canadian only. They do online orders so that might be an option.
Another pic of the "cool cube" It's intended to be an incandescent lamp powered by 4 AA batteries. It has a switch on the bottom that is turned on by pushing the cube down. The fact that it has a holder for 4 AA batteries made it perfect for many of my projects. I'll post more pictures but I'll try to shut up about it cause it's not necessary for this project.
The most important thing you need is a cheap pair of amplified PC speakers. I paid $10 for a pair of "Kinyo" ? speakers and detached the power/input/output wires. The amplifier is an AC powered 6 watt stereo amplifier.
Some items you need. Wire strippers ( the automatic kind to the lower right are fantastic !) various crimps/marrettes . binding posts, bananna plugs, wire snips,a drill and various drill bits. Dremel multitool/bits. Third hand is very useful.
Here are some banana plug test leads I made that work well for many uses. also see some of the varied posts.
here is a pic of the amplifier board I removed from the PC speakers. Notice that the board is labelled . SP-R is right. and SP-L is Left.
cut these wires (output) and solder them to the binding posts. +=Red -=Black. The "ear" jack will still work to listen with headphones. (this is good if you built an audio signal generator and you want to listen to it quietly.)
Here are a few more pictures to show the board and how I fixed the transformer to the "cool Cube" housing. Remember that you could use any project box you want. I cut a small block of pine and used a dremel to cut out the battery holder. I used the drill and multiple bits to locate the holes for power cords etc. in my project casing.
So, this uses the mini jack as an audio input. I've built a few 555/556/74hc (etc. signal generators) this seems to be the perfect way to amplify the signal for headphones/oscilloscopes etc. I think that the package looks nice and is modular due to the use of bannana plug jumper leads. This project will even power led's to music etc. And as long as you stay away from the mains supply, Who cares if you blow a few cheap components and even this $10 amp.?