TEA6320 bassed Sound fader electronic project circuit and explanation

Using the TEA6320 integrated circuit , manufactured by Philips Semiconductors , you can design a very simple , very useful sound fader electronic project circuit that can be very useful in many audio systems projects .
The sound fader control circuit TEA6320 is an I2C-bus controlled stereo preamplifier for car radio hi-fi sound application . The source selector selects one of 4 stereo inputs or the mono input. The maximum input signal voltage is Vi(rms) = 2 V. The outputs of the source selector and the inputs of the following volume control parts are available at pins 8 and 10 for the left channel and pins 23 and 25 for the right channel.
The volume control function is split into two sections: volume I control block and volume II control block.
The control range of volume I is between +20 dB and -31 dB in steps of 1 dB. The volume II control range is between 0 dB and -55 dB in steps of 1 dB.
The bass and treble control functions can be switched off via I2C-bus. In this event the internal signal flow is disconnected. The connections B2L and B2R are outputs and TL and TR are inputs for inserting an external equalizer.
The balance and fader functions are performed using the same control blocks. This is realized by 4 independently controllable attenuators, one for each output. The control range of these attenuators is 55 dB in steps of 1 dB with an additional mute step.
As the two audio channels (left and right) are independent, two comparators are built-in to control independent mute switches.
To avoid a large delay of mute switching when very low frequencies are processed, the maximum delay time is limited to typically 100 ms by an integrated timing circuit and an external capacitor (Cm = 10 nF).
The mute function can also be controlled externally ,if the mute pin is switched to ground all outputs are muted immediately (hardware mute).
The power supply should include a VCC buffer capacitor, which provides a discharging time constant .
This sound fader electronic project circuit needs to be powered by a DC power supply circuit that will provide an output voltage between 7.5 volt and 9.5 volt , typically a 8.5 volt DC power supply circuit is required .

ic-HT82231 Animal sound generator using

This is an animal origin, a simple circuit. Interesting, because an IC package and a simple good
Operation of the circuit. This circuit, an IC, a number HT82231 IC package that has other audio source animals. The origin of the sound depends on the switch S1-S8 of switch.
Each is a different animal sounds and choose to press each LED1, LED2 lights alternately as it sounds they hear. The R1, R2 LED forward current limiting for each signal will come out on pin 19, to expand the force with Q1. There is also a sound that VR1 can be adjusted as soon as we hear. Or slow as you like C1, C2 prevents low-frequency noise. And high frequencies.

IC LM324 Sound Meter easy testing circuit and explanation

The circuit below responds to sound pressure levels from about 60 to 70 dB. The sound is picked up by an 8 ohm speaker, amplified by a transistor stage and one LM324 op-amp section. You can also use a dynamic microphone but I found the speaker was more sensitive. The remaining 3 sections of the LM324 quad op-amp are used as voltage comparators and drive 3 indicator LEDs or incandescents which are spaced about 3dB apart. An additional transistor is needed for incandescent lights as shown with the lower lamp. I used 12 volt, 50mA lamps. Each light represents about a 3dB change in sound level so that when all 3 lights are on, the sound level is about 4 times greater than the level needed to light one lamp. The sensitivity can be adjusted with the 500K pot so that one lamp comes on with a reference sound level. The other two lamps will then indicate about a 2X and 4X increase in volume.
In operation, with no input, the DC voltage at pins 1,2 and 3 of the op-amp will be about 4 volts, and the voltage on the (+) inputs to the 3 comparators (pins 5,10,12) will be about a half volt less due to the 1N914 diode drop. The voltage on the (-) comparator inputs will be around 5.1 and 6.5 which is set by the 560 and 750 ohm resistors.
When an audio signal is present, the 10uF capacitor connected to the diode will charge toward the peak audio level at the op-amp output at pin 1. As the volume increases, the DC voltage on the capacitor and also (+) comparator inputs will increase and the lamp will turn on when the (+) input goes above the (-) input. As the volume decreases, the capacitor discharges through the parallel 100K resistor and the lamps go out. You can change the response time with a larger or smaller capacitor.
This circuit requires a well filtered power source, it will respond to very small changes in supply voltage, so you probably will need a large filter capacitor connected directly to the 330 ohm resistor. I managed to get it to work with an unregulated wall transformer power source, but I had to use 4700uF. It worked well on a regulated supply with only 1000uF.
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