Digital volume control - The Tiny Audio Amplifier kit is a good choice for battery operation. It is based on LM386 IC.
Digital Volume Control - This circuit could be used for replacing your manual volume control in a stereo amplifier. In this circuit, push-to-on switch S1 controls the forward (volume increase) operation of both channels while a similar switch S2 controls __ Contact: IQ Technologies
Direct Injection Box for Musicians - Don't put up with hum. This versatile DI box converts an unbalanced input to a balanced output signal and includes a 3-band equaliser. __ SiliconChip
Direct Injection Box for Recording & Psystems - An essential companion for the mixer for stage or recording work __ Designed by Rod Elliott ESP
Directional Microphone - With the possible exception of sophisticated shotgun microphones or microphone arrays, effective directional microphones usually employ parabolic reflectors or horns. Parabolic reflectors about the size of a modern satellite receiver antenna, perhaps 2 feet across, perform quite well but are a bit obtrusive. These are commonly seen on the sidelines at football games. But it turns out that simple horns or cones work very well as directional sound collectors, are easier to handle, and don't look like microphones. They do look a bit like megaphones, witches' hats, or traffic cones, all of which might make great microphones! In fact, a pair of cheerleader megaphones might make a great two-way communications system __ Contact: Charles Wenzel of Wenzel Associates, Inc.
Discrete JFET Bass Preamp - I wanted a warm, tube-like sound with as few stages as possible. I believe that part of the clarity and directness of a tube amp comes from the fact that there are so few phase invertions compared to a normal solid state (not to mention the different kinds of unpleasant distortions made by op-amps). So I came up with the absolute minimum setup: Two (inverting) gain stages and one source follower/impedance converter. JFETs, because they behave similar to tubes at overload conditions (of course, nothing but a tube really sounds like a tube...) The EQ Section was originally planned to be like an Ampeg SVT filter. It sounded good, but I could not get rid of the hum (used a small transformer for the filter coil), also it was rather noisy compared to the rest of the preamp. So I had to make a compromise (op-amps!), but this circuit really works fine, and most important, it can be bypassed. In fact I rarely need it, just use the "Ultra High"- and "Ultra-Low"-switches. __ Designed by Albert Kreuzer
Distance Sensing-devices for wireless distance & position Determination - Since the early seventies we did build sonar devices to control our self made analog electronic music synthesizers. In those years, simple to use transducers were not readily available on the electronic component market and so, we had to make our own, based on designs used for underwater hydrophones. (Quarz crystals, inductive devices, self made condensor microphones etc...). Although the focus of our research later on became doppler based sonar and radar movement detection and gesture analysis __ Designed by Dr.Godfried-Willem Raes
Distortion effects using an LM386 Audio Amplifier IC - A few months ago, Aron Nelson released the Smash Drive. The circuit ingeniously used an LM386 audio power amp chip to produce great distortion sounds. Aron based his work on that of Tim Escobedo. Tim's Stupidity Box was another great sounding unit and beautifully simplistic. The Smokey Amp by Bruce Zinky was another design that used a 386 for some great sounds. __ Contact: holler @ runoffgroove.Com
DIY 50W Amplifier based on ICL8063 - This is a handy, easy to build general purpose 50 watt amp. The amp has an input for a radio, TV, stereo or other line level device. It also has a phono input for a record player, guitar, microphone. __ Designed by Aaron Cake
DIY Bias Probe - DIY Bias Probe __ Designed by Guitar Effect RC Keen
Dog Repellent Project - The electronic dog repellent circuit diagram below is a high output ultrasonic transmitter which is primarily intended to act as a dog and cat repeller, which can be used individuals to act as a deterrent against some animals. It should NOT be relied upon as a defence against aggressive dogs but it may help distract them or __ Designed by Popescu Marian
Door Phone Intercom - A simple 2 way Intercom based on the LM386386 using 8 ohm speakers __ Designed by Laurier Gendron & Andy Collison
Double D - Two channels of buxom distortion. __ Contact: holler @ runoffgroove.Com
Dracula MOSFET Power Amplifier - Simple Class-A power amp that uses complementary pair of IRFP240 and IRFP9240 MOSFET transistors. The intention of this project was to build simple, but high quality amplifier. The aim was reached by integrating the whole input driver in one IC and adding high power transistor output stage. As you can see on the schematic the amplifier has very simple structure. At the input there is high quality and relative high power TI IC OPA552. It drives a complementary pair od MOSFET transistors IRFP240 and IRFP9240. The gain of the whole circut is set to 40x. The TL431 is to set the operation point of output transistors. The idle current is set to 80mA, so the amplifier works in A class for it's first few watts. The more current the longer it stays in A class, but the more power to be dissipated. With 80mA and these heatsinks it still goes very hot after long playing.
DSP Musicolour Light Show; Pt.2 - In last month's first part, we described the circuit operation of the DSP Musicolour. In this instalment, we guide you through the construction. The operation of the firmware and troubleshooting tips will be described next month. In this issue there are also notes and errata for the schematic published last month. __ SiliconChip
DSP Musicolour Light Show; Pt.3 - In last month's article, we detailed the construction of the DSP Musicolour. In this month's article, we guide you through the final testing of the DSP Musicolour and give troubleshooting tips. We also explain the operation of the firmware in more detail as well as discussing possible accessories. __ SiliconChip
DSP Musicolour Pt.1 - This DSP Musicolour accepts audio input signals and drives coloured lights "in tune" with the music. Its four output channels respond to different audio frequency bands and the brightness of the lights is in direct proportion to the amplitude of the frequency components. A dot-matrix LED menu display is featured on the front panel and this also functions as a spectrum analyser or VU meter. __ SiliconChip
DSP Musicolour Pt.4 - With a small and low-cost add-on PC board, the DSP Musicolour can be operated via an infrared remote controlvery handy if you want to use it in hard-to-reach places. __ SiliconChip
Dual Amp PCB - containing schematic and gerber files. For Use with Opto Compressor Project __ Contact: info @ forsselltech . com
Dual Analogue Frequency Shifter - An audio effects frequency shifter similar to the famous Bode/Moog design from the 1970s. __ Designed by Henry
Dual JFET-992/993 PCB - containing schematic and gerber files. For Use with Opto Compressor Project __ Contact: info @ forsselltech . com
Dual Microphones Separate Voice From Noise - 06/23/94 EDN-Design Ideas The circuit in Fig 1 uses a pair of microphones to extract a voice from a noisy background. You must mount electret microphones X1 and X2 on the left and right sIdeas of the user's chest. Sound sources not equidistant from the microphones experience a phase shift. Because sound travels at 1120 ft/sec, the maximum phase shift for this design's/ Design by Samuel Kerem, Infrared Fiber Systems, Silver Spring, MD
Dual parallel buffered effect loops with blend control. Schematic & perfboard/PCB layouts - The Splitter-Blend provides two buffered parallel effects loops with a Blend control. Also, a phase polarity switch is included to allow phase matching of the effect loops. Possible uses are blending two sets of effects placed in the loops, a signal splitter, a simple mixer, or to blend an effect with the dry signal. The phase inverter can be used for interesting results when mixing dry and effected signal. __ Contact: holler @ runoffgroove.Com
Dual Transformerless Class a Discrete Mike Preamp - Uses JMP-1 Modules __ Contact: info @ forsselltech . com
DVD Recorder + TV Camera Make Cheap Data Logger - Sometimes recording the results of a test requires as much ingenuity as designing the product. Consider a situation which requires the collection of many different variables over a long period of time . . . Hobby Circuit designed by David A. Johnson P.E.-April, 2005
Dynamic Microphone Amplifier - Audio levels can be monitored using a small panel meter with this circuit built from discrete components. The circuit has a flat frequency response from about 20Hz to well over 50Khz. Input sensitivity is 100mV for a full scale deflection on a 100uA meter. Built on two common emitter amplifiers, the first stage has a preset resistor which may be adjusted for a FSD. The last stage is biased to operate at roughly half the supply voltage for maximum ac voltage swing. Audio frequencies are passed through the 10u dc blocking capacitor and the full wave bridge rectifier converts the signal to a varying dc voltage __ Designed by Andy Collison
Dynamic Microphone Preamplifier - A low noise pre-amplifier suitable for amplifying dynamic microphones with 200 to 600 ohm output impedance. __ Designed by Andy Collison
Dynamic microphone to electret microphone input - Circuit which works as an preamplifier which allows you to replace an electret microphone with a dynamic microphone. __ Designed by Tomi Engdahl
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