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Microphone Polarity Tester - Many things can go wrong in a modern recording studio, but few are as difficult to track down as reversed microphone polarity. When a microphone is placed in front of a sound source, a positive pressure on its diaphragm caused by forward-moving air results in a positive voltage on one of its output pins and a negative voltage on the other. But which pin is positive? These days most microphones have XLR output connectors, with Pin 2 used for the positive voltage output and Pin 3 for the negative. But you can't always count on this, especially if the microphone is an older model, or was ever repaired or otherwise rewired. __ Designed by Ethan Winer Microphone pre-amp with high emphasis - Ham RadioSchematic __ Designed by Guy Roels ON6MU
Microphone PreAmplifier - This is a simple microphone preamplifier circuit which you can use between your microphone and stereo amplifier. This circuit amplifier microphone suitable for use with normal home stereo amplifier line/CD/aux/tape inputs. This microphone preamplifier can take both dynamic and electret microphone inputs (preamplifier provides power foe electret microphone elements) . The idea of this circuit is to keep the design as simple as possible __ Designed by Tomi Engdahl
Microphone Preamplifier - A low noise pre-amplifier suitable for amplifying dynamic microphones with 200 to 600 ohm output impedance. __ Designed by Andy Collison
Microphone Test Oscillator - This unit would be mounted in a small plastic or preferably metal box, with a 9V battery, level control, a male XLR connector (same as on a mic) and a switch. Current drain is low, since the circuit only uses one dual opamp. There is no need for a high quality device, and a 1458 (or 4558 which is somewhat better but still cheap) is all that is needed __ Designed by Rod Elliott ESP
Microphone Tester - This circuits is handy for finding an intermittent short or open in a microphone cord or switch. It produces a week tone in the microphone so that you can flex the cord and operate the switch to find faults. It won't find an open shield or a short from __ Designed by Andrew R. Morris
Microphone to Neck Loop Coupler for Hearing Aids - Hearing-aid wearers often have difficulty understanding conversations in noisy environments, especially if they have switched their personal hearing aid from microphone mode to T-coil mode. This projects solves that problem.__ SiliconChip
Microphone uses "phantom power" - 08/30/01 EDN-Design Ideas The electret microphone capsule is similar to those commonly used in telephones, cassette recorders, and computers. The element functions as a capacitor with a fixed trapped charge. Sound pressure moves a diaphragm, producing variations in the capacitance. This action produces an ac-output voltage with an extremely high source impedance Design by Bruce Trump, Texas Instruments, Tucson, AZ
Mike Muter for Singing Guitarists - The average musical Do-It-Yourselfer starts building guitar effects by making a distortion pedal of some sort. It's a good introduction to musical electronics, and pretty simple as well, since getting a circuit NOT to be linear has never been hard. But there comes a time when you have to stop thrashing the strings in your bedroom, get up on stage and *play*. When you get to there, you run into all kinds of little problems that you never encountered back in your room. __ Designed by R.G. Keen
Mike Pads & Other Small Gadgets - Includes Active Direct Box circuit
Mike Preamp Power Supply with Phantom Power - Uses a single 48 VAC center-tapped transformer __ Contact: info @ forsselltech . com
Miniature FM (Voice) Transmitter - Schematic + Notes (Construction) + Parts __ Designed by Tony van Roon VA3AVR
Miniature FM Transmitter - This miniature transmitter is easy to construct and it's transmissions can be picked up on any standard FM receiver. It has a range of up to 1/4 of a mile or more. It is great for room monitoring, baby listening, nature research, etc. L1 is 8 to 10 turns of 22 gauge hookup wire close wound around a non-conductive 1/4 inch diameter form __ Designed by Andy Wilson
Miniature FM Transmitter - Schmatic with parts list and notes __ Designed by Tony van Roon VA3AVR
Miniature FM Transmitter #1 - This miniature transmitter is easy to construct and it's transmissions can be picked up on any standard FM radio. It has a range of up to 1/4-mile (Tony van Roon's 400 meters) or more, depending on the line-of-sight, obstructions by large buildings, etc. It is great for room monitoring, baby listening, nature research, __ Designed by Tony van Roon VA3AVR
Miniature FM Transmitter #5 - 4 Transistor TransmitterCircuit + Parts Lits + Notes __ Designed by Paul K. Sherby
Miniature FM Transmitter #6 - up to 500 meter rangeCircuit + Parts List + Notes __ Designed by Tony van Roon VA3AVR
Miniature FM Transmitter #7 - There is no thrill like the thrill you get from operating equipment you have built yourself. If you have never built a project from a magazine before, let this be your first--you'll see how much satisfaction and fun you can have! __ Designed by Tony van Roon VA3AVR
Miniature MW Transmitter - circuit diagram of simple medium wave transmitter using BF494B. This simple transmitter have a range of 200 meters
Modification of Panasonic Backelectret Capacitor Microphone WM GOAT Digikey P9967 ND - This drawing describes the conventional hookup and option where FET is connected as source follower with3 wires to preamp__ Linkwitz Lab
Op-Amp Microphone Preamplifier - A high quality microphone preamplifier using a single power supply, suitable for dynamic or electret microphones. The op-amp used can be any low noise, high performance type, e. g. NE5534, TL071, OPA 371 etc __ Designed by Andy Collison
Perimeter Monitor - Using a single cable such as speaker wire or doorbell cable, this circuit can be remotely positioned, for example, at the bottom of a garden or garage, and used to detect all sound in that area. The cable can be buried in a hosepipe or duct and is concealed out of sight. The mic is an ordinary dynamic mic insert __ Designed by Andy Collison
Plans for a Shotgun Microphone - Also with Tube Lengths based on 1/4 Octave Frequencies.
___ Designed by G.L. Chemelec
Pop Free Microphone On/Off Switch Circuit - This circuit uses a simple technique to eliminate the usual “pop” sound when an electret type microphone is switched on or off. The circuit is completely passive and will work on dynamic and electret type microphones. . . Circuit by David A. Johnson P.E.-February, 2002
Portable Microphone Preamplifier - This circuit is mainly intended to provide common home stereo amplifiers with a microphone input. The battery supply is a good compromise: in this manner the input circuit is free from mains low frequency hum pick-up and connection to the amplifier is more simple, due to the absence of mains cable and power supply __ Contact: Flavio Dellepiane, fladello @ tin.it
PortaPAL Public Address System-Part 2 - Here's the good oil on putting it together and getting it to work. We even describe an easy way to build a box.__ SiliconChip
PreAmplifier Computer Microphone - This circuit was submitted by Lazar Pancic from Yugoslavia. The sound card for a PC generally has a microphone input, speaker output and sometimes line inputs and outputs. The mic input is designed for dynamic microphones only in impedance range of 200 to 600 ohms. Lazar has adapted the sound card to use a common electret microphone using this circuit __ Designed by Lazar Pancic from Yugoslavia
PreAmplifier for Microphone or guitar use - suitable for guitar or microphone use __ Designed by Bob Blick
Radio Shack Pressure Zone Microphone PZM Modifications - Schematic + Notes
Sensitive FM Transmitter - Circuit + Parts List + Notes __ Designed by Tony van Roon VA3AVR
Shortwave Bug - Circuit and notes only, no circuit description given. __ Designed by Tony van Roon VA3AVR
Simple Circuit microphone preAmplifier #2 - This is a simple microphone preamplifier circuit which you can use between your microphone and stereo amplifier. This circuit amplifier microphone suitable for use with normal home stereo amplifier line/CD/aux/tape inputs. This microphone preamplifier can take both dynamic and electret microphone __ Designed by Tomi Engdahl
Simple Circuit Stereo Electret Microphone PreAmplifier - The leftmost 10k resistor supplies plug-in-power to the electret, forming part of the FET amplifier in the electret capsule. This could be anything from 2k to 10k, the higher the better the stereo separation (another mic derives bias from the same rail) . Apparently higher values also lower distortion, and the best bias power circuits involve actually breaking a trace on the electret capsule to allow the use of both a drain & source resistor, but I’m not going that far.
Simple Circuit Wireless Microphone - This wireless FM microphone is simple to build and it has a useful transmitting range (over 300 meters in the open air) . Despite its small component count and a 3V operating voltage it will easily penetrate over three floors of an apartment building. It may be tuned anywhere in the FM band (87-108MHz) and its transmissions can be picked up on any standard FM receiver.__ hobbyteam @ hobby-hour.com
Simple FM Transmitter - There is no thrill like the thrill you get from operating equipment you have built yourself. If you have never built a project from a magazine before, let this be your first--you'll see how much satisfaction and fun you can have! __ Designed by Tony van Roon VA3AVR
Stereo Electret Microphone PreAmplifier - The leftmost 10k resistor supplies plug-in-power to the electret, forming part of the FET amplifier in the electret capsule. This could be anything from 2k to 10k, the higher the better the stereo separation (another mic derives bias from the same rail) . Apparently higher values also lower distortion, and the best bias power circuits involve actually breaking a trace on the electret capsule to allow the use of both a drain & source resistor, but I’m not going that far.
Super Spy Transmitter Bug - A very small home made FM transmitter Bug using a single transistor and with a transmission range of 200 meters. This FM transmitter Bug is very easy to build. The size of the circuit board is ONLY 22mm x 10mm. |
