Free electronic circuit design and schematic diagram
Graphic equalizer is a filter which it’s overal frequency response can be adjusted easily by sliding the potentiometer knob, and the potentiometer’s knob positions will naturally mimic the frequency response of the filter, and this is very user friendly. Many methods have been developed by electronic engineers to make audio equalizer, such as Baxandall’s type and Gyrators emulation type. Here […]
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A second order filters can be constructed using LC (inductor-capacitor) passive circuits, and they have been implemented for radio frequency for cheap and simplicity. For audio frequency range, unfortunately the size for the inductor and capacitor become too large, space consuming, and the most important is they’re really expensive. Because of this, active filter is commonly used for audio application. […]
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What we can do with a stereo voltage-controlled volume control? There so many things, we can control our audio using a DAC which is controlled by a microcontroller, or we can use mono potentiometer with RC filter to minimize the scratched sound produced by a dirty potentiometer (I see this method in one of SONY audio products). Using a voltage-controlled […]
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Operational amplifiers for tone control circuit application require high slew rate, wide bandwidth, high input impedance, and high output current characteristics, and CA3140 is suitable for this purpose. Look at the following tone control circuit’s schematic diagram for the design. The tone control circuit in the figure above use a very popular Baxandall tone control configuration circuit, which has unity […]
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This tone control circuit use very popular Baxandall configuration, a simple circuit configuration that provides boost and cut control in continuous manner. This circuit is very cheap to build, and it’s commonly implemented in commercial product. Here is the circuit’s schematic diagram: The transistors can be substituted by any general audio transistors with small current gain more than 100 (BC547, […]
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This audio power amplifier circuit is simple and robust, and use discrete component available on many electronic part stores. The final transistors use 2N3055 and MJE2055. Here is the circuit’s schematic diagram: The MJE2055 is an npn transistor, but the configuration with TIP42A make the whole combination of TIP42A and MJE2055 are seen as pnp transistor. This audio amplifier circuit […]
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Feedback in public address amplifier is something that should be avoided. The ideal solution is by adjusting the microphone and the speaker position, but it’s not always possible in many situation. Using frequency shifter to change the output frequency 10Hz lower than the input frequency can solve the problem, but it’s too expensive for a low cost public address system. […]
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