SimpleAVR over at the 430h forum shows off his Educational BoosterPack 8 bit FFT Spectrum Analyzer project:
SimpleAVR comes up with unique Launchpad projects. These include his wire clock and spectrum analyzer projects. This time he wired the CircuitCo Educational BoosterPack to a Launchpad to sample audio and have the LCD display a spectrum.
Educational BoosterPack 8 bit FFT spectrum analyzer - [Link]
Here is a design guide from Maxim describing various classes of audio amplifiers. [via]
This has been a brief survey of the many types of audio amplifiers commonly used in designs today. Clearly, when designing an audio circuit for any type of device, care should be taken in determining the audio amplifier topology best suited to the application. A good understanding of these different classes of audio amps will help you choose the best audio amp for your design.
App note: Various audio amplifier classes - [Link]
To reach a maximum mechanical stability, many Sonitron piezo components are now available even with a foam tape.
Sonitron piezo components feature a high reliability, resistance to harsh conditions and also to vibrations. Despite these features, usually one of the weakest points (as for the vibration-resistance) is the joint of leads with a PCB.
That´s why company Sonitron offers a simple but very efficient solution also improving their assembly. This solution is based on a glued both-sided foam tape, shaped exactly according to dimensions of a given component. Sonitron mars this option as an „FP“ – Foam Patch and is available at SMA(T), SMB, SCS and SMAC series. Upon order we´re able to provide you any component listed in the list of types available with this option. Price difference in comparison to a standard version is approx. 0.20-0.45 Eur depending on a size of a given component.
In case of interest, please contact us at firstname.lastname@example.org.
Let vibrate only a membrane - [Link]
Here is a simple and reliable 2.5W Stereo Audio Amplifier based on TEA2025 IC. Nydal Dahl writes:
I have been looking for a good stereo amplifier circuit diagram for a long time. I am not a HiFi geek, I just wanted to build a simple stereo amplifier that could drive some speakers for my desktop computer.All the schematic diagrams that I could find seemed to involve lots of hard-to-find components or you had to use it together with a pre-amplifier or some other amplifier stage. It was always something that made me hesitate.
TEA2025 – 2.5W Audio Stereo Amplifier - [Link]
The LM4780 is a great part to build your own Audio Power Amplifier. It is not a new part, but is a very popular part used audio amplifier circuits. This part is spec’d to drive two 8Ω loads at 60 watts. The part comes in a wide TO-220 package and can be mounted to a heat sink. Pay attention to the voltage on the thermal tab it is a voltage supply not gnd.
This circuit demonstrates how easy it is to configure the amplifiers.
Build your own Audio Amplifier Circuit - [Link]
This is an all-digital-hardware Theremin. The Digital IR Theremin uses comparators, digital logic and a single 555 timer for tone generation to make it so that when you wave your hand in front of the infrared proximity sensor, it outputs a tone with varying pitch depending on how far away your hand is from the sensor!
Digital IR Theremin - [Link]
Gio @ diyaudioprojects.com point us to:
This is a project that has roots to back about 2 years ago. I wanted a quality headphone amplifier to be an addition to my Hi-Fi stereo system. It was to be something to use when I didn’t want to disturb everyone else in the house. I tried several different tube types in the amplifier design process. I used 6J6, 12AU7, 6SN7, 6CG7/6FQ7 and 12AT7. Generally all worked, but none seemed to have either the needed output level or didn’t match well (likely to the choice of transformers) and sounded on the dull side. The 6DJ8 (ECC88) dual triodes worked like a charm. They had the combination of sufficient current flow, modest voltages on the anodes (important for the matching transformers) and enough gain to make the amplifier sing. The next best tube type was the 6CG7/6FQ7. Almost as good, but they are getting a bit scarce and the new production JJ E88CC are now quite common and reasonably priced. I am sure other triodes could be used and there is no reason why a high impedance ( on the primary side) small push-pull output transformer would not work. I doubt that you can find one much cheaper than the matching transformers I used. Certainly not with similar response and distortion characteristics.
DIY 6DJ8 (ECC88) Tube Headphone Amplifier - [Link]
Reliable loudspeakers needn´t be expensive. K50/8 from company Visaton is a good example of a universal louspeaker suitable even to less favor conditions for a very affordable price.
K50/8 belongs to 5 cm (2“) industrial loudspeakers with an increased resistance. IP65 (from the side of membrane after building into an appropriate housing) says it all. Plastic membrane from mylar is UV-resistant and a metal basket ensure a long-term stable properties in a wide range of temperatures. K50 easily handles what it is intended for – reproduction of voice and various sound in a wide frequency range (naturally except low and highest frequencies). K50 also meets another requirement important for the most of applications – small profile – 17mm only. Similarly like the most of small loudspeakers, also K50 is virtually omnidirectional even at higher frequencies (-5db/90°/8000 Hz)..
Thanks to its small dimensions, low profile, resistance and last but not least also an affordable price is the K50 a suitable component for a sound output of various devices like audio door-keeper, lifts, machines and control panels. K50 and many other Visaton components are our standard stock items. In case of interest in non-stock types, please contact us at email@example.com
Add a sound to your devices – for an outstanding price - [Link]
Bruce Heran writes:
It has been a while since I did anything really crazy in DIY and had it work out far above my expectations. Such is the case for the Mini Blocks. I had a lot of extra parts lying around (really a huge amount of them) and tried to figure out what I could build. Two small chassis about 5 inches by 9 inches by 2 inches (12.5 X 22.5 X 5 cm) were just begging for a project. They are just the right size for lots of things. I first thought of a pair of SET amps. But since I didn’t have any suitable single ended output transformers I nixed that idea. A preamp perhaps could be built on one of the chassis. Since I have many preamps now that didn’t really get the nod either. A pair of small push-pull amplifiers was next on the list. Maybe, but I have so many amps now that it doesn’t make sense either. Since this hobby doesn’t always have to make sense, that is what I built. Clever observers will note that each of the mini blocks is a whole lot like half of a PoddWatt amplifier
Mini Block Push-Pull EL84 (6BQ5) Valve Amplifiers - [Link]
A new chip from NXP can boost the output power of micro speakers by more than five times, vastly improving the sound quality of mobile devices. By driving over 2.6 watts RMS into micro speakers that have previously been limited to 0.5 W, the TFA9887 IC will give mobile phones, portable music players and tablets much louder sound, deeper bass, and higher sound quality without risking speaker damage.
Adaptive excursion control measures the actual excursion of the speaker membrane to ensure that it never exceeds its rated limit. Real-time temperature protection measures the voice-coil temperature directly to prevent thermal damage. An advanced clip avoidance algorithm monitors audio performance and prevents clipping, even when the power supply begins to sag. Bandwidth extension increases the low frequency response well below speaker resonance. And an intelligent DC-to-DC boost converter maximizes audio headroom from any supply level despite battery undervoltage. The chip automatically adapts to any changes in the speaker – including ageing, damage to the enclosure, and blocked speaker ports – helping to optimize performance and maintain the desired sound quality. [via]
Novel Speaker Driver Delivers Hyperaudio from Mobile Devices - [Link]