The buttons can be used to control MPD. Distributions like Volumio and RuneAudio are based on MPD, therefore this could be interesting for many readers. Peter has provided the Python script that controls everything. You can download it here: mydisplay-20140409. Note that we provide this “as is” without any support. However, the code is clean and well-documented. Therefore it should be relatively easy to adapt it to your needs.
Our HiFiBerry project is still ongoing. The PCB design is almost finalized and we expect the device to be ready in about 4-6 weeks. With HiFiBerry you will get an inexpensive and high-quality sound card for the Raspberry Pi. However, there is one thing it cannot provide: high-resolution sound, that means sampling frequencies above 48kHz are not supported. There are a lot of Pros and Cons for or against higher samples rates than 48kHz. At least when it comes to post processing like equalizing or digital crossovers, higher samples are a good idea.
You could also add an external USB sound card. But we are looking for a real DIY solution ;-) The 2nd revision of the Raspberry Pi provides access to the I2S pins of the processor. You can add an I2S capable ADC or DAC on these pins.
Unfortunately, the Linux kernel of the standard Raspberry Pi does not support devices connected to the I2S pins. Therefore you need to compile your own kernel. Check out the “Noise is good” blog for more information. Hmm, looks like an interesting project for another Raspberry add-on board. We will have a look into this.
You can buy 1Gsamples/s oscilloscopes now for a few hundred euros. But there are also entry-level scopes available in the range of 800-1000€. Does it make sense to invest in the more expensive devices? Check out this comparison of two Rigol devices:
There is another interesting thing about the Rigol DS2000 series featured in this video: there is a key generator out that allows you to use the features of the expensive devices even with the base device. All features are enabled and disabled just by software. Is it legal? We don’t know? But a more interesting question is: What will Rigol do about it? My guess is, that Rigol is aware of the issue and is happy about it. It’s great marketing: Sell the same product at different price points depending on the willingness to pay.
The LM317/LM337 is one of the most used circuits for low power audio applications. The performance is good. For most applications, these integrated circuits work really well. But sometimes you may want something better and more modern. There are two interesting ICs for audio applications:
TPS49xx/TPS30xx: This pair can be a nice replacement for the 150mA LM317T/LM337T. They are not too expensive, therefore you may even use more multiple devices of you need more than the 150mA. One specific use case is using them as regulators after a switched mode power supply. However there is one disadvantage for DIY use: They come in a 0.65mm pitch MSOP package. But even these devices can be soldered without a reflow oven. Check out Daves EEVBlog for a tutorial how to do this.
Some phono enthusiasts prefer audio equipment with vacuum tubes. I’m also fascinated by these “old” equipment, but did not build a tube amplifier or preamplifier by myself. While the circuits usually are quiet simple, most of the performance of tube amplifiers come from the realisation. The grounding concept or the placement of transformers can make the difference between a great and a bad amplifier – even with exactly the same circuit.
If you still think, that you want to build your own phono preamplifier based on tubes and even want to use it for very low MC signals, check out this project: MC/MM phono preamp. Even if you can’t understand the german text, the pictures of the mechanical construction are worth a look
There are lots of DIY DACs available, but not many ADCs. If your are looking for an ADC, checkout this PCM1803 breakout board from Watterott.
Everybody is talking about 3D printing today, but there are lots of other cool production tools out there that can
This looks like the ultimate CNC mill to produce your own loudspeakers. It consumes much less space than usual portal mills and can be transported easily. Unfortunately this is only a prototype today. Let’s see if this device will be available for sale in the future. I don’t expect it to be cheap.
The kickstarter project for this high-precision desktop CNC machine has started. It has been designed with PCB prototyping in mind.
You can buy this small desktop CNC mill for less than 500$. I don’t know how this compares to OtherMill. But I guess, it is good enough for PCB prototypes
This company wants to create an automated electronics production robot. The project is in a very early state yet, but the goals look promising.