{"product_id":"phantom-powered-microphone-preamplifier-low-noise-professional-quality","title":"Phantom Powered Microphone Preamplifier – Low Noise – Professional Quality","description":"\u003cp\u003eThe project presented here is a professional quality\u003cspan\u003e \u003c\/span\u003e\u003cstrong\u003ePhantom powered Microphone pre-amplifier\u003c\/strong\u003e. The project is built using the\u003cspan\u003e \u003c\/span\u003e\u003cstrong\u003eINA163\u003c\/strong\u003e\u003cspan\u003e \u003c\/span\u003echip from TI. The Chip is a very low-noise, low-distortion, monolithic instrumentation amplifier. R2 and R3 provide a current path for a conventional\u003cspan\u003e \u003c\/span\u003e\u003cstrong\u003e48V phantom power source\u003c\/strong\u003e\u003cspan\u003e \u003c\/span\u003efor a remotely located microphone. A slide switch SW1 allows phantom power to be disabled. C6 and C8 block the phantom power voltage from the INA163 input circuitry. Additional input protection against ESD and hot-plugging, four\u003cspan\u003e \u003c\/span\u003e\u003cstrong\u003e1N4148\u003c\/strong\u003e\u003cspan\u003e \u003c\/span\u003ediodes D1, D2, D3, D4 connected from the input to supply lines. R7 and R8 provide a path for the input bias current of the INA163. Gain is set with a variable resistor, PR1, in series with R4. R4 determines the maximum gain. The total resistance, R4 + PR1, determines the lowest gain. A special reverse-log taper potentiometer for PR1 can be used to create a linear change (in dB) with rotation. LED D5 is used as a power indicator. L1, L2, C7, C10, and C11 components protect the inputs from EMI and RFI noise.\u003c\/p\u003e\n\u003ch3\u003eOptional DC Output Control Loop\u003c\/h3\u003e\n\u003cp\u003eInput offset current (typically 100nA) creates a DC differential input voltage that will produce an output offset voltage. This is generally the dominant source of the output offset voltage. With a maximum gain of 1000 (60dB), the output offset voltage can be several volts. This may be entirely acceptable if the output is AC-coupled into the subsequent stage. An optional circuit is provided to tackle this problem. An inexpensive FET-input op-amp U2A in a feedback loop drives the DC output voltage to 0V. Op-Amp is not in the audio signal path and does not affect signal quality.\u003c\/p\u003e\n\u003ch3\u003eInstall the Following Components for DC Output Control Loop\u003c\/h3\u003e\n\u003cul\u003e\n\u003cli\u003eU2A = OPA2134 SOIC8\u003c\/li\u003e\n\u003cli\u003eC9 = Ceramic Capacitor 0.1uf\/50V SMD Size 0805\u003c\/li\u003e\n\u003cli\u003eR6 1Mega Ohm 5% SMD Resistor Size 0805\u003c\/li\u003e\n\u003cli\u003eOmit Resistor R5\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003ch3\u003eConnections and Other Details\u003c\/h3\u003e\n\u003cul\u003e\n\u003cli\u003eCN1: Pin 1 = +48V DC Phantom Power Input, Pin 2= GND\u003c\/li\u003e\n\u003cli\u003eCN2: Pin 1-2 = VCC +15V DC, Pin 2-3 = GND, Pin 4-5 VEE -15V DC\u003c\/li\u003e\n\u003cli\u003eCN3: Pin 1 = BB Microphone – VIN, Pin 2 = GND, Pin 3 = AB Microphone + VIN\u003c\/li\u003e\n\u003cli\u003eCN4: Pin 1 = Audio Output, Pin 2 = GND\u003c\/li\u003e\n\u003cli\u003eD5: Power LED\u003c\/li\u003e\n\u003cli\u003eSW1: Phantom Power Enable\/Disable Switch\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003ch3\u003eFeatures\u003c\/h3\u003e\n\u003cul\u003e\n\u003cli\u003ePower Supply Dual 15V DC (+\/-15V DC)\u003c\/li\u003e\n\u003cli\u003eOn Board Power LED\u003c\/li\u003e\n\u003cli\u003eSlide switch for Phantom Power Enable\/Disable\u003c\/li\u003e\n\u003cli\u003e3 Pin Screw Terminal for Microphone Connections\u003c\/li\u003e\n\u003cli\u003e2 Pin Screw Terminal for Audio Output\u003c\/li\u003e\n\u003cli\u003e2 Pin Screw Terminal for Phantom Power Input 48V DC\u003c\/li\u003e\n\u003cli\u003e6 Pin Male Header for Power Input\u003c\/li\u003e\n\u003cli\u003eGain Up to 1000\/V (60dB)\u003c\/li\u003e\n\u003cli\u003ePotentiometer PR1 Gain Adjust\u003c\/li\u003e\n\u003cli\u003ePCB Dimensions 60.17 x 39.85mm\u003c\/li\u003e\n\u003cli\u003e4 x 3mm Mounting Holes\u003c\/li\u003e\n\u003c\/ul\u003e","brand":"dotfry","offers":[{"title":"Default Title","offer_id":47037672784044,"sku":"A119","price":50.0,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0757\/6436\/7532\/files\/A119A.jpg?v=1787573609","url":"https:\/\/dotfry.com\/products\/phantom-powered-microphone-preamplifier-low-noise-professional-quality","provider":"dotfry","version":"1.0","type":"link"}