Recently I put together a media player. My house hasn’t seen a stereo in years and I was getting tired of always having to have ear buds in to listen to anything. In the back of my workshop was an old set of speakers. The last remnants of my old stereo setup.
The first Volumio box I made is a portable version; well it would be more portable if it had a proper battery connected to it, but it makes it to work with me. Knowing how well Volumio works already, it was an easy choice for the new setup.
Next was an amplifier. There are several to choose from; a little too low-end all the way to Great Mother McGerty. I found one that was in my budget and reviewed quite well. I picked the HiFiBerry Amp2. It puts out up to 60w per channel. Since I am no longer in the arena of stereo wars with my neighbors, it will work out perfect. I did a little digging around my parts bin and sorted through my old laptop power supplies to find one from a Dell, 19v , 5A, which matches to it quite well.
I don’t have a 3D printer and it was getting frustrating finding a project box, which I liked, that would accomodate the height of the amp. Time for a wood working project. They always seem a little more stastifying in the end. I constructed a simple, partial box.
I some spare spruce from another project and put it to good use here. The back of the box will be open to aid in air flow. The bottom, for now, is friction fit to the sides of the box. My goal is to find some small magnets from old phone or tablet cases and use them on the sides and bottom for a more secure fit.
Sand, paint, repeat for a nice smooth finish. The RPi and amp are attached to the bottom which can fall away, and the back is left open for airflow. No indicator lights or the such on this version.
The volume control is of my own design. It uses an Elm Electronics 401 debounce chip and a Bourne rotary encoder with indents and a push switch. The HiFiBerry board is wired directly up to the power supply. A retired laptop gave up its’ 19v 5A brick.
To keep things on the cool, I added a fan to the case. I also didn’t want it blowing all the time as this device will just be left on all the time. The fan is a small 1.5″, 5v, brushless that appeared in the parts bin. After a little researching I made a PWM board using a TIP120, resistor, and diode. A python script is used to control the fan according to the temperature.
Also check out the oscilloscope project page where the PWM design is tested.
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