I designed and built this stomp-box forGrammy-winning resophonic guitar player Stacy Phillips. Stacy typically uses two transducers on his Dobro-style instruments: a piezo element mounted internally and a gooseneck-mounted electret microphone positioned an inch or so above the resonator cover. When I built this preamp in 1996, his microphone cons
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isted ofan AudioTechnica AT831b capsule connected to anAT8530 power module. The power module could use batteries or 5-52 V phantom power, and had an XLR male output jack. A boost/cut tone control centered on 1 kHz (this is the approximate fundamental resonant frequency of the Dobro`s resonator and proves to be important for setting up the instrument`s amplified sound). A defeatable low-pass filter to eliminate a high-frequency "tink" sound, which Stacy found irritating. We identified this sound as pick (attack transient) noise with an audible bandwidth of 12-20 kHz. Link here to a FFT output (Fast Fourier Transform) from Sound Designer II which helped us determine this (please use your browser`s "back" button to return). Compact and rugged construction suitable for portability and road use. Stacy reluctantly agreed to let the unit`s power supply use an external wall-wart transformer rather than batteries. From my notes I have scanned the Dobro preamp`s schematic diagrams and modification records. You can see these images by clicking the links below. (You will need to use your browser`s "back" button to return. ) Circuit The unit has two independent input channels feeding an Analog Devices OP275-based mixer, with a rotary fader for each. The 1/4-inch input for the piezo transducer leads to an SSM2139-based low-noise non-inverting gain stage with a 1 M-ohm input impedance. The XLR female microphone input, with selectable +15V...
This project fits more for custom made battery casing that can have more space to hide things inside. This switch with few alterations can be used for any other project as well but is designed based on e-bike needs! This project use a clever functionality of....
The circuit described here uses ultrasonic oscillations and operates based on the propagation velocity of these oscillations in the air. Thus, we can easily determine the distance of two points if the time within which the wave travels this distance is....
Sometimes the precious metals are hidden too deep and are not detected except with complicated devices. In many cases, however, small pieces of precious metal buried near the surface can be detected by relatively simple means. Everyone is very attractive to....
Many times for various reasons we forget or can not water the plants that we have in our homes. And many humidity sensors units just notify us with a beeping sound or with a flashing light, that the pot needs watering. But what if we are away from home? This....
The principle behind a metal detector is really very simple. Proof of this is the circuit that follows, in which it proves that the construction of a metal detector can be done in the minute, with few components that we find very easily everywhere. With the....
The sub-harmonic bass generator is a sound producing unit for guitars. The sound it produces looks very much like that of the bass guitar. The octave generator is sometimes quite unusual since it does not produce any of the usual ways of coloring the sound,....
In the past the sounding (sea bottom measurement) was done with the "bullet", that is, with a heavy lead object that the seamen plucked into the sea hung from a calibrated rope. As soon as the "bullet" reached the bottom, the depth appeared directly from the....
This Amplifier was designed to have the following specifications: Distortion less than 0.1% at full power of 100W even at 20KHz. Power has to be attributed to an extended bandwidth. The output transistors must be protected against short circuits. The power....
A series of LEDs serve to alert the gardener when plants need water. Using two conventional digital integrated LEDs and a series of LEDs, we make a very useful device for gardening. The device detects the amount of water in the pot and alerts the grower.....
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