Microphone Circuits

Microphone preamplifier with TLC251

A microphone preamplifier using: om CMOS op amp with its own battery, is small enough to be placed in a case of small microphone. The amplifier operates from a 1.5V battery cathode mercury low supply currents. This preamp will operate at very low power and maintain a reasonable frequency response as well. The TLC251 is operating in low bias (operating at 1.5 V) draws a supply current of only 10 and has a year - frequency response of 3 dB 27 Hz to 4.8 kHz. With 8-pin grounded, which is designated as the polarization state high limit increases above 25 kHz. Supply current is only - 30 pA under these conditions. ..

4 microphones mixer circuit with TL081

A TL081 op amp is used as a high impedance to low. converter and a signal mixer. The input impedance is about 1 megohm and the output impedance is about 1 kohm. Two 9 volt batteries are used as power source. ..

9V LED light organ

This is a nice example circuit that can be used at parties. The four LEDs blink to the beat of the music. The light organ using a microphone responds to sound. T1 amplifies the signal from MIC. The sensitivity can be adjusted with P1. T4 controls the LEDs. These are preferably high intensity LEDs. ..

Whistle on / off switch

This is an extension of the CMOS toggle flip flop circuit shown in the "Circuits controlling relays" section with the addition of two bandpass filters and condenser microphone so the relay can be toggled by whistling at it. The condender mic used is a PC board mount Radio Shack #270-090C. The filters are tuned to about 1700 Hz, or the third Ab above middle C on a piano keyboard which is a fairly easy note for me to whistle. Resistor values for the filter can be computed using the three formulas below but we need to assume a gain and Q factor for the filter and the Q of the circuit must be greater than the square root of (Gain/2). ..

Phantom PS for Microphone

The circuit is shown in Figure 1, and as described above, uses a voltage doubler rectifier. Diodes D1 and D2 are 1N4004 or similar. From there, a pair of resistors provide additional smoothing to the secondary filter caps. R3 is used to balance the voltage across C3 and C4, and must not be omitted. The regulator was a very common topology prior to the introduction of 3-terminal regulator ICs, and is used here so that high voltage regulators are not needed. These are much harder to get than the standard versions, and still require additional circuitry because 48V versions are not made. Although the circuit looks complex, it is very easy to build (especially if the PCB is used)...

PC Microphone Preamplifier

Soundblaster soundcard series (SB16, SB32, AWE32 and AWE64) have all a microphone input designed to be used with the electret microphones which come with the soundcard package (some packages) or with separate microphone designed to be used with SoundBlaster soundcards (there are separate microphones and some monitors have built-in microphones like this). Because the microphone input needs very high input levels it is not suitable to be used with any other micophone type than elecret capsule microphones. If you connect a dynamic microphone (which gives typically few mV voltage) and try to record it you will get very low signal level with lots of noise...

Microphone Preamplifier BC547B

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 to be easy to build. That was my goal when I needed a simple external microphone preamplifier for my mixer. The performance of the circuit is nothing superior but can be used with many not so serious projects...

Dynamic to Electret microphone adaptor circuit

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. The circuit below is a typical wiring used with electret micrphones connected to 3.5 mm mono plig unput (as used in vidoe cameras and some portable audio recoders). Toy cna use the wiring below just by replacing the electret capsule on the left with my dynamic microphone amplifier circuit described above...

This design was born of frustration with the mic preamp in my Sony R91. It clips at ridiculously low levels, basically it has 28mV of headroom to deal with an input that could be as high as 1800mV (depending on mic & volume), so this design attempts to cure that by : A: Providing a higher electret bias voltage, 9V through a 10k resistor to give the mic's fet more headroom. (The R91 provides 2.5V through a 6k8 resistor.) B: Having much greater preamp headroom, and bypassing the R91's mic preamp altogether, using a hi-fi or low noise op-amp to go straight into the line input. ..

Vocal Zapper

All vocal eliminators start with the assumption that the lead vocal in a recording is in the center of the stereo field - which means that it is equal amplitude and phase in both left and right channels. Subtracting one channel from the other removes this highly correlated signal while leaving the uncorrelated signals in the channels unchanged. Since kick drum and bass are often recorded at stereo center the time constant of C3 and R12 is chosen so that these signals are blocked from the non-inverting input so they pass to the final output without being zapped. ..

Auto Microphone Muter

If you've crossed the line and play guitar or bass and also sing in a band, you're almost certain to have run into the situation that you step away from the mike to do a solo (or one of those neato, expressive dance steps, or a facial impression of the pain you're pouring out to make these dulcet tones...), and had the mike pick up some unfortunate noise to funnel into the PA. You may even have fumbled for the mike mute switch as you stepped away and back to it, but that's almost terminally clumsy, as you have your hands full of your instrument. Wouldn't it be nice if the microphone was only "listening" when you stepped up to it?..

Microphone Preamplifier with 5532 NE

This is a good example preamplifier for microphones that can be used in mixing consoles. The circuit uses a dual op-amp, type NE 5532. The amplifier must be adjusted. This connect the power supply and control over P1 such that half the supply voltage (6 V) on pin 3 of IC1 is. P2 is then adjusted to the desired volume...

Basic Microphone preamplifier

This preamplifier amplifies the signal from a microphone, an amplifier so that it can be further strengthened. The circuit supplies an output signal line. With two transistors, it is not difficult to build such a circuit. The amplifier produces noise Weining. In the drawn embodiment the circuit suitable for microphones from 500 to 600 ?. R1 200 ? for microphones should be reduces to 220 ? and C1 should be increased to 4.7 uF. The gain is set by R2. If the average declared value of 22 kOhm used. The maximum gain is about 200 times...

741 Microphone amplifier

This preamplifier uses a type of IC 741, and can boost a microphone signal to line level. The microphone signal is connected to the "input" put. Any power for the microphone jack of the "food" are met. Here half the supply voltage. Using the gain potentiometer P1 can be adjusted from 10 to 101 times...

Microphone balanced preamplifier

A professional suggestion for those interested in improving sound. The circuit constitutes the part of input mixing console sound from the microphone or source of high level . It can be used on it's own or be multiplied to the number of channels required. It includes all the useful functions such as, phantom power , reverse face, signal attenuation for avoiding distortions from high level signals regulating channel gains and the rest of the stages will be added next stages ,for full mixing console. Attention must be paid to the quality of the materials used. This circuit may used, previous to Parametric EQ circuit. ..