1.5 Volt Amplified Ear:  Useful to listen in faint sounds1.5-Volt Battery operation, includes electret microphone preamplifier which runs from1.5-Volt DC and can directly drive32 Ohms impedance mini-earphones (Circuit added 9/04)

2 Wire Remote Microphone Amplifier:  uses special Amplifier module from Op-Amp Labs (Circuit / schematic design added 6/06)

AN-60-032  Uses and Advantages of “MERA” Dual Matched MMIC Amplifiers:  Application Note - MiniCircuits.com  (Circuit / schematic design added 6/06)

AN827: Using KEELOQ to Validate Subsystem Compatibility:  Microchip Application Note - Published 13-Feb-02   (added 2/06)

Balanced Low Noise Microphone Preamp:  very low noise, close to the theoretical minimum, high hum rejection and variable gain with a single rotary pot, similar to that used in many professional grade mixing desks (added 8/03)

Basic electret microphone powering circuits :  This is the basic electret microphone powering circuit which you can use as generic reference when receivign circuits which use electret microphones. The putput impedance is determined by R1 and R2. If you leave out R2 the output impedance is roughly the resistance of R2.  (added 2/06)

Battery Powered Electret Microphone #2:  Note: scroll down to this this circuit.  This circuit can be used with normal tape recorders and sound cards which usually are designed for dynamic microphones. When you build this circuit inside the microphone case (or to small external box) you can make yourself an universal microphone out of an electret capsule. (Circuit / schematic design added 6/06)

Battery powered electret microphone:  Note: scroll down to this this circuit.  This circuit can be used with normal tape recorders and sound cards which usually are designed for dynamic microphones. When you build this circuit inside the microphone case (or to small external box) you can make yourself an universal microphone out of an electret capsule. (added 2/06)

Big-E Stereo Parabolic Microphone:  This device is a stereo amplifier for a high sensitivity stereo parabolic microphone. It can be used for listening to distant sounds. Typical parabolic microphones are monophonic, this unit has a stereo audio path that helps produce more realistic sounding audio. The Big-E can be used with headphones or as an audio source for a stereo tape recorder or a PC sound card. This circuit also works nicely as a remote stereo audio receiver for accompanying a video surveillance system. It is capable of operating on the end of a four wire shielded cable that is more than 100 feet long. For remote operation, a set of inexpensive amplified PC speakers can be connected to the outputs for monitoring the sound....   (Circuit / schematic design added 6/06)

Binaural MICs:  (Electronic Schematic / circuit added 4/02)

Boundary Layer Dish Microphone:  ideas for a directional microph1-assembly   (Electronic circuit added 5/02)

Computer Microphone #2:  (added 6/03)

Computer microphone:  (Electronic circuit added 4/05)

Condenser MIC Audio Amplifier:  (Circuit / schematic design added 6/06)

Condenser Microphone hookup:  (Electronic Schematic / circuit added 4/02)

Constant Power PAN Control:  Circuit for Microphone for Microphone Audio Mixing (Electronic circuit added 5/02)

Digital Quality Microphone Pre Ampl. using the Model 425 OPAMP :  (added 6/03)

DIY Microphone for Sony MD R35 Minidisc Recorder:  simple electret microphone (Electronic circuit added 5/02)

Dual JT-MB C Microphone Combining Circuit:  connect two microphones to1-microph1-input (Electronic circuit added 5/02)

Dual Microphones Separate Voice from Noise:  06/23/94 EDN-Design Ideas / (Circuit / schematic design added 6/06) 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 sides 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 mounting scheme is about 0.5 msec. This phase shift corresponds to a 90 degrees phase shift at about 1000 Hz. Thus, all sounds in the vocal frequency range, except the user's voice, tend to cancel....  

Dynamic Microphone Amplifier:  (added 6/03)

Dynamic Microphone Preamp :  Notice how the transistor bias current flows through the microphone. A similar circuit can be used with an 8 ohm speaker but in that case you would put it in place of the emitter resistor.  (added 2/05)

Dynamic Microphone to Electret Microphone Input #2:  (Electronic Schematic / circuit added 4/02)

Dynamic microphone to electret microphone input:  This is a simple microphone preamplifier circuit which you can use between your dynamic microphone and any equipment designed to work with an electret microhone (2 wire connection to electret capsule). This amplifier amplifies the low level signal to the levels used by electret microphone input and uses the power from the device.... (added 2/06)

ECM MIC PreAmplifier:  (Electronic Schematic / circuit added 4/02)

Electret Microphone Connection:  how to connect electret microphone (Electronic circuit added 5/02)

Electret Microphone Powering:  (Electronic Schematic / circuit added 4/02)