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
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. 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
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. 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.
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. 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. What is required is a little load isolation. And as always.
Audio - Do-It-Yourself Circuits DIY-page Welcome to the Gyraf Audio DIY-page..... Please read this first!! The projects described on these pages are not commercial in any way. This means that we DO NOT sell PCB's, kits, or anything like that. It also means that any for-profit use of the information on these pages is strictly prohibited. Please DO NOT contact us regarding parts or info for the DIY-projects, as we don't sell anything related to these - they're kept strictly non-commercial. 20. Here's the link to the Prodigry-pro forums (AKA GroupDIY) - our meeting place and hangout for all things audio, electronic and DIY. Gyraf Do-It-Yourself Circuits This pages contain information about building your own professional audio equipment. Comments and corrections are more than welcome, but I can't promise to reply to all mail. Also you should take extreme caution when working with mains voltages and the very high DC voltages ocurring in tube circuits. Basic safety rules: DIY Forums and groups: The G1176:
Fuzz Central -- Making the world a fuzzier place for 5 years 20Hz to 200Hz Variable High-Pass Filter Posted Jan 12, 2012 at 9:39 am The circuit was designed to create a high-pass filter that can be variably change to work with frequency range from 20 Hz to 200 Hz. High Pass Filter – an electronic circuit that allows the passage of high frequencies while opposing any unwanted low frequency components TL072 – a low noise JFET input operational amplifier with features such as common-mode input voltage range, high slew rate, operation without latch up, compensated internal frequency, high input impedance at the JFET input stage, low noise, low total harmonic distortion, protected from output short circuit, low input bias and offset currents, wide common-mode and differential voltage ranges, and low power consumption The operation of the high-pass filter in a stereo system is represented by the functionality of a tweeter where a capacitor is connected in series as it provides the treble audio to the speaker. Source:users.otenet.gr/~athsam/variable_filter.htm
DIY Audio Projects Forum • Simple Passive Tone-Control I have built up quite a collection of headphone amps and now venturing into higher voltage/wattage amps. My workbench/home office now has a variety of sources and amps, but one DIY item that was missing was an EQ of some sort. I have a few preamps, but I really did not want to add any more gain and noise to an already congested system. I found an answer in a simple but genius tone-control by Tony van Roon ... xtor5.html. I drew the amp up in Tina and sim'd the outputs and made only a few minor changes. The tone control sits in between two switch boxes (back to back) so that I have three sources to a switch box, tone control, switchbox, the amps. Since the control is passive it will attenuate about -20db at the baseline and the pivot point is around 800Hz.
Basic BJT Amplifier Configurations Common Base Configuration Here the base is the common terminal. Used frequently for RF applications, this stage has the following properties. Low input impedance, high output impedance, unity (or less) current gain and high voltage gain.Common Collector Configuration This last configuration is also more commonly known as the emitter follower. This is because the input signal applied at the base is "followed" quite closely at the emitter with a voltage gain close to unity. The properties are a high input impedance, a very low output impedance, a unity (or less) voltage gain and a high current gain.
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. This capacitive resistance, more properly called reactance, is at the heart of all active audio filters. Before getting down to the nuts and bolts, let's first review some filter basics using terms a recording engineer can readily understand. 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. A typical octave graphic equalizer has a Q of 1 on each of its control bands. 1. 2.