Audio Filters -- Theory and Practice Audio Filters - Theory and Practice by Ethan Winer This article first appeared in the August 1981 issue of Recording-engineer/producer magazine. In a previous article I explained that capacitors are essentially frequency-dependant resistors. One type of filter is the high-pass (or low-cut) shown schematically in Figure 1, along with the resultant frequency response. The low-pass filter, shown in Figure 2, is constructed by transposing the resistor and capacitor. A third kind of filter is the band-pass shown in Figure 3. On a parametric equalizer, there is a control for varying bandwidth, or how far from the center frequency the boost and cut action extends. Although the bandwidth in this simple circuit can be changed by varying the ratio of the inductor to the capacitor, a much better approach is to use an op-amp to provide positive feedback. A typical octave graphic equalizer has a Q of 1 on each of its control bands. 1. 2. TABLE 1: Component Values for 60 Hz.
Siemens full-surface induction cooktop lets you arrange the pans wherever you like Siemens' full-surface induction cooktop allows up to four pieces of cookware to be placed anywhere on its surface Image Gallery (4 images) Earlier this year at CES 2012, Siemens subsidiary Thermador unveiled its Freedom Induction Cooktop that allows pots and pans of various sizes to be placed anywhere on its surface instead of being constrained to fixed cooking zones. Now Siemens has shown its own full-surface induction cooktop that provides the same freedom of cookware placement. Unlike other induction cooktops that use four inductors under a ceramic surface to provide four fixed cooking zones, Siemens’ unit boasts up to 48 conductors to form a continuous cooking surface. Placing a pot anywhere on the ceramic surface activates a group of induction modules that automatically interconnect to form a single unit that can be controlled like a dedicated cooking zone. Operating instructions in up to 15 languages can also be viewed in the cooktop’s display. Source: Siemens About the Author
High Quality Sound Mixer High Quality Audio MixerRod Elliott (ESP) Introduction This project is probably the most ambitious so far, and can be expected to be very expensive. The project is presented in parts, and Part 1 shows the mic/line module and has some background information on noise measurements and the general philosophy behind the project. Description Since the project is presented in stages, this is an index for the various modules, and as the system is developed will also be the place to look for updates and other information. The additional modules, metering and a complete system layout will be added to the list as they are developed. NOTE: There has been a surprising amount of interest in this project, with a common requirement being a smaller version (an almost equally common request has been for a bigger version, too). Projects Index Main Index
Revolvy 2in1 - Mixer and Blender Concept by Wonkook Lee & Yanko Design Blend and Mix in a Swoop The Revolvy 2in1 has a very curious shape for a blender and mixer. When not in use, the appliance just folds up to one discreet hanging gadget, freeing up precious kitchen-counter space. Ken Stone's Modular Synthesizer Band Pass Filter for music synthesizers. This module is a simple bandpass filter with manually adjustable center frequency and Q. It is good for setting up artificial resonances for virtual instruments. A little on how it works: The schematic of the Band Pass Filter. CX on the overlay is simply an optional part to allow easy conversion to an AC coupled output. Construction The component overlay of the earlier version. The component overlay of Rev 1. Before you start assembly, check the board for etching faults. When you are happy with the printed circuit board, construction can proceed as normal, starting with the resistors first, followed by the IC sockets if used, then moving onto the taller components. Take particular care with the orientation of the polarized components, the electrolytics, diodes, and ICs. When inserting the ICs in their sockets, take care not to accidentally bend any of the pins under the chip. I have allowed space on the PCB to mount 16mm pots directly on the PCB.
Best Alarm Clocks - 10 Funny Alarm Clocks and Reviews - Womans Day For most people, getting out of bed in the morning is a bit of a struggle. Luckily, the 10 clocks below are here to help. Some wake you up with an annoyingly loud noise, while others won't shut off until you complete a task--but they all promise to get even the sleepiest sleepyhead up and moving. Start Your Engines It’s full speed ahead as soon as this Genuine Hotrod Hardware drag-racing alarm clock goes off. Hide and Go Seek There's no excuse for waking up late with this alarm clock. Attention! Ever wonder what waking up in the army would be like? Duck for Cover This Sonic Grenade alarm clock is guaranteed to get your sleepy children out of bed. Blast Off The Rocket Launcher alarm clock will really "launch" you from your bed. Puzzled There's probably nothing more annoying than putting together a puzzle before you've even had a cup of coffee, but with the Puzzle Alarm Clock, you'll have to do just that. Get Up, Stand Up Don’t Drop the Bomb Cock-a-Doodle-Doo It Keeps Going and Going
Audio projects, circuits and audio kits Muting Transistor Attenuator Circuits and the 2SC2878 by Jim Keith | Among semiconductors, the muting transistor and its audio application is perhaps the most obscure and poorly understood of all. There is extremely little information on this subject available on the internet and what is available is sketchy. This discussion is an attempt to tie the pieces together and to add some insight –I... CMoy Headphone Amp by DigiKey | The CMoy headphone amp is a popular headphone amplifier that is small enough to carry everyday and powerful enough to drive headphones at higher levels than normal. Hybrid Headphone Amp Potentially, headphone listening can be technically superior since room reflections are eliminated and the intimate contact between transducer and ear mean that only tiny amounts of power are required. Audio Compression Amplifier /AGC This is an audio compressor/AGC (automatic gain control) with an astonishing 75db input voltage range. Kojak Siren by P. LA4440 Audio Amplifier
25 Simple Gadgets and Accessories - FizX Entertainment | FizX Entertainment You know what they say, “less is more”, and these simple (yet awesome) gadgets are the perfect examples. While the “Slide to Unlock” doormat and superhero bookends don’t feature the latest in technology, they most certainly are eye candy as well as conversation pieces. Continue reading to see twenty five more. 25. 24. 23. 22. 21. 20. 19. 18. 17. 16. 15. 14. 13. 12. 11. 10. 9. 8. 7. 6. 5. 4. 3. 2. 1. Read More: Updated New Gadget Post Look At Our Amazing Must Have Gadgets For Summer 2013 Click For More Limiter Important! New version of this circuit exists. Click here! Why it is important to use a limiter? Audio signals as music or speech have big dynamic ranges. There are silent and loud sections. Following circuit is the simplest limiter possible. Technical specifications Supply voltage: 10-14 V stab. Output voltage vs. input voltage (with C8 placed) Schematic diagram Parts list Resistors: R1 - 68 k R2 - 22 k R3 - 180 k R4 - 10 M R5 - 10 k R6 - 47 R R7 - 240 k R8 - 1,5 k R9 - 820 R Capacitors:C1 - 100 p (ceramic) C2 - 1 n (plastic) C3, C6, C12 - 100 n (ceramic) C4, C11, C13 - 100 u (electrolytic) C5 - 0,33 u (tantalum) C7, C8 - 10 u (electrolytic) C9 - 220 n (plastic) C10 - 47 n (ceramic) C14 - 470 n (plastic) Misc. Don't place the C8 if you don't want to use whole dynamic range. PCB layout
The PriNXT: A Working Printer Made From Lego | PCWorld The next time you have a quick black and white image to print you might try sending it over to print out on your Lego bricks. A new project, called the PriNXT, is a simple but effective printer built out of everyone’s favorite toy. The PriNXT by Leon Overweel is made from Lego’s Mindstorm system that lets you add motors and some programming magic to your Lego projects. Even though he's just 14 years old, Leon managed to build the PriNXT along with a number of other Lego projects--including a Skype-controlled Lego Car. The printer essentially works like a traditional dot-matrix printer. The printer does have some serious limitations at the moment: Its print area is just 50 by 50 dots, and in order to print an image, Leon has to convert it to black and white and then into binary. [World of Mindstorms via MAKE] Like this?
Single Op-Amp Twin-T Band-Pass and Notch Filter | Simple Circuit Diagram This is a Single Op-Amp Twin-T Band-Pass and Notch Filter circuit. This circuit uses the twin-T topology which requires one or two op amps and three resistors and three capacitors. That’s mean this topology based on a passive (RC) topology. It is not difficult to match the six passive components, but it is critical. we can use single value of capacitance and a single value of resistance to create C3 and R3. Here is the schematic diagram of the circuit: The component values are determined by following equation: Bandpass configuration: C1 = C2 = C R1 = R2 = R R3 = R/2 C3 = 2C Fo=1/(2pRC) R4 and R5 are used to control gain with R4>100*R5 Notch configuration: R1 = R2 = R C1 = C2 = C R3 = R/2 C3 = 2C Fo = 1/(2pRC) R4=R5:HIGH If the components are matched too closely, the bandpass circuit will oscillate.
How to Make Office Weapons Out of Office Supplies Wow, if you thought working at your white-collared job, sitting in your well equipped air-conditioned office, thinking that this is probably one of the safest place to be… you may just want to think twice about that. The office is a jungle. Beside having to watch your back against office colleagues who may be wolf in sheep’s clothes, you may just have to watch out for those seemingly utilitarian office supplies, because in conjuncture with other seemingly innocent office supplies, they may just result to be one of the deadliest office weapon yet. Below is an example of our favorite office supplies- binder clips, turned into office weapons. Take a few binder clips of varying sizes, turn them upside down, and clip the smaller binder clips inside the larger clips. It should look like this when the larger binder clips have clipped the smaller ones. Remove all the binder clip handles. Add another 2 larger binder clips on top of the smaller edge with a rubber band in between. stumbleupon
tonepad -- a resource for d.i.y. music projects Simple Mixer Schematics Simple Mixer Schematics PREAMBLE: I've been cooking audio circuits for so long now I no-longer need a recipe. A lot of the theory I have forgotten over the years because I've just gotten to know the circuits by instinct. But this should serve as something of a guide to designing mixers from scratch. The idea: Most people reading this would be well aware of what a mixer is used for but I'll reiterate here. The job of an Audio mixer is to combine various audio signals into a single audio signal. It is better known in electronic terms as a summing circuit. Audio is of course an AC (Alternating current) signal but if we look at the incoming signals as a frozen moment in time we can represent it as 2 or more DC voltages. If we had two signals to be mixed. When you get to the stage of adding many signals together, the complexity grows. Because each incoming signal has it's own load impedance it is impractical just to wire all of them together and hope for the best. And as always.