Stereo Bass Booster Circuit with Simple Mixer

Bass Booster

A Bass Booster is an audio device, which amplifies the low frequencies (bass) within the audio spectrum. This operates in a similar manner to an audio equalizer. General-purpose equalizers are often not effective at boosting very low frequencies, and therefore many electronics enthusiasts make their own circuit to achieve this purpose. Using following circuit you can boost frequencies below 60Hz.

Schematic

This circuit is an active circuit and used TL074, which include separate four op-amps. Alternatively, you can use any general-purpose op amp such as LM324, TL084, etc. This circuit is not only a bass booster it also include a simple mixer circuit. U1A and U1D are act as mixer, U1B and U1C for the base boosting. I design this circuit for electronic switching. Therefor I used two transistors for it. To enable bass boost connect ‘ubb’ to positive supply. You can use normal switch for it. In addition, it is possible to enable bass boost by applying voltage signal to ‘ubb’, which come from a micro-controller or any other source. This circuit can operate in either single supply or dual power supply.

For single power supply

• Omit C20 and C21.
• Connect positive supply to VDD and Ground (0v) to GND or VAA.
• Max Supply voltage is 12v.

For dual power supply

• Remove J3 (jumper), C15, R19 and R20.
• Add jumper (0 Ohms) for R20 it.
• Connect positive supply to VDD, negative for VAA and Ground (0v) to GND.
• Max Supply voltage is +/-12v.

Please ignore the U2, R21, C16, C18 and P1. Those are not necessary for the operation of this circuit. These parts are optional because that this circuit and PCB were designed for my personal project.

Now connect output of this circuit with amplifier input and give your input to the mixer side. This circuit is ideal for high quality sound. If you want that unique clean high-bass sound then this circuit can provide it.

Schematic and PCB files were added to the download and you can download from it below.

X-Bass Sch & PCB

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10 Band I2C Graphic Equalizer Circuit - 16F628 TEA6360

Updated:

• 2016-08-17 - Added small application for calculate frequencies and parts.

10 Band Equalizer

A graphic equalizer is a high-fidelity audio control that allows the user to see graphically and control individually a number of different frequency bands in a stereophonic system. A typical graphic equalizer consists of several audio filter/amplifiers, each centered at a specific frequency in the audio range. Most graphic equalizers have two identical sets of filter/amplifiers, one for each channel in a stereophonic system.

The gain controls in most graphic equalizers are slide potentiometers that are adjusted by moving a controller up or down. Gain is increased by sliding the upwards. The slide potentiometers for each channel are placed side-by-side, with the lowest-frequency unit at the left and the highest-frequency unit at the right. In this way, the positions of the buttons appear to follow a graphical curve that represents the gain as a function of frequency for each channel.

By using following circuit you can build a 10 band stereo graphic equalizer that can be controlled via I2C system. For this circuit I used two of TEA6360 ICs. Each IC contains two serial five bands equalizer blocks. Therefore, we need two ICs for 10 bands. We can reduce the size of circuit because all the function can be drive via i2C. So that, we do not need connect potentiometers to control the gain of frequency bands like an ordinary equalizer. In addition, we can reduce cost and complexity of circuit using this IC.

Schematic

Circuit on PCB

In my demo code, I used 16F628A micro-controller and single button to set equalizer modes. The modes are ‘Flat’, ’Rock‘, ’Pop‘, ’Jazz‘ and ’Party’. The status will indicate by five LEDs those connected to PORTA. In addition, selected mode saved to device Eeprom and load to ICs when start up. However, according to your choice you can able to change the code.

For example if you need to set gain for each frequency manually, then you can add 1 button to each channel and total 10 buttons. For another example, you can add 3 buttons. One button to raise the gain and other to lower and 3rd one for select desired frequency.

The center frequency of each bands are 31Hz, 62Hz, 125Hz, 250Hz, 500Hz, 1KHz, 2KHz, 4KHz, 8KHz and 16KHz. the Q (quality) factor is 1 to 1.2 and PCB, full schematic and sample code can be downloading in below.

Part List

• C04, 07, 08, 09 = 0.37uF
• C10, 11, 12, 13 = 0.18uF
• C14, 15, 16, 17 = 0.01uF
• C18, 19, 20, 21 = 0.047uF
• C22, 23, 24, 25 = 0.022uF
• C27, 28, 30, 31 = 0.01uF
• C32, 33, 34, 35 = 0.0052uF
• C36, 37, 38, 39 = 0.0027uF
• C40, 41, 42, 43 = 0.0015uF
• C44, 45, 46, 47 = 720pF

TEA6360

The 5-band stereo equalizer is a 12C-bus controlled tone processor for application in car radio sets, TV sets and music centers. It offers the possibility of sound control as well as equalization of sound pressure behavior of different rooms or loudspeakers, especially in cars.

FEATURES

• Monolithic integrated 5-band stereo equalizer circuit
• Five filters for each channel
• Center frequency, bandwidth and maximum boost/cut defined by external components
• Choice for variable or constant Q-factor via I2C software
• Defeat mode
• All stages are DC-coupled
• I2C-bus control for all functions
• Two different module addresses programmable.

10 Band Equalizer
Calculator App

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USB Controlled 8x40 Dot Matrix Moving Display Circuit - 18F2550

2015-04-12 Initial release
2015-04-16 Wrong Configuration Bits - Fixed

This dot matrix moving display message board will be of five, 8x8 dot matrix, which will be able to display 10 different messages and maximum 60 characters of each. You can set messages by using PC application that created by me using visual basic and those messages will show on matrix display. When the circuit is disconnected form PC then default messages displayed on the display.

Circuit Diagram

PIC18F2550 is the micro-controller and main part of this circuit. This IC used because it has built-in USB transceiver that used to communicate with PC application. PORTB of IC controls the row of Matrices. This PORTB pins then connected to display through the ULN2803 IC, which consists of 8 Darlington arrays. Because micro-controller unable to handle heavy load. In the diagram, you can see 8 NOT gates. These gates used only simulation in Proteus. Therefore, you should replace with these gates with ULN2803 IC. The columns are driven by the outputs of a 40-bit serial-in-parallel-out arrangement constructed by cascading five 74HC595 ICs. The 74HC595 device is an 8-bit serial-input and parallel/serial output shift register. The serial output feature allows cascading of multiple 74HC595 devices. The time format of PC must be in English, otherwise time will not display properly on the display. LED is indicated that whether USB cable connected or not and Scrolling speed of circuit can be change by varying the value of VR1. Supply voltage for this circuit is 5v.

The PC application and other files can be download from below link.

PC App
HEX File

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USB HID Bootloader Circuit - 18F4550

Update:

28/11/2015
If you are use mikroC PRO, then tick the Long Hex format in output settings and rename the generated hex file to scp.hex. Finally run mod.exe. It will generate new hex file (mod.hex) and use it with PICDEM software. Otherwise, program may not work correctly.


Boot-loader is a program which helps to program the micro-controller device without using external programmer. It is possible to burn the hex code even if the PC doesn't have a serial port or any other tools.

Required tools for Boot-loader are:

• USB cable to connect board to the PC
• A micro controller with already flashed boot loader program

Boot-loader circuit

The boot-loader starts after Power-On or Reset. The boot-loader checks if pin RE3 is low or high:

• RE3 = low (0V) : PIC starts in boot-loader mode
• RE0 = high (5V) : PIC starts user application

Install Boot-loader program

For installing boot-loader program, we need an external programmer. This is a one time process which doesn't need to repeat. Use any programmer like JDM, PicKit, ICD3 to flash the provided boot-loader program USB HID Bootloader.hex.

After successfully programming, connect your device to the PC's USB port (if not already connected). Please make sure that the boot-loader entry condition (RE3 = 0) is fulfilled!

Windows should detect a new USB device. Now open boot-loader PC software and click connect, browse hex file, begin upload.

After finishing upload, click execute. Device will reset automatically and start your program.

Example

void main(); void interrupt() { //-------- interrupt ----------- } void interrupt_low() { } void Vectors() org 0x800 { //-------- remap --------- asm { goto _main //0x800 nop nop goto _interrupt //0x808 nop nop nop nop nop nop goto _interrupt_low //0x818 } } void main() { //----- Main -------- OrgAll(0x800); asm {goto Skip_Vectors} Vectors(); asm {Skip_Vectors:} /* Your Code goes here */ }

Mod.exe
PC Software
Firmware and Schematic

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8x32 LED Matrix Real Time Clock Circuit with Alarm - 18F2550

Most of electronic enthusiasts are very much interest about the LED matrix displays. So if you are one of them this is for you. If you are not familiar with LED matrices at all, please read these two experimental tutorials Basics of LED matrix display and scrolling text message on an LED matrix .

LED Matrix Clock

LED matrix displays are very popular in these days and most of people are love it but wonder how it can construct. So that I decide to provide this post for you. This project is about constructing a mono-color LED matrix display based real time clock. It can display time, date, and room temperature alarm with chime function. You can control this clock using four switches (Mode, Enter, Up, Down) and can changed the speed of scrolling by RV2.

Matrix Clock

The main IC of this project is PIC16F2550 micro controller which controls all the sections, and display the LED matrix with the help of 74HC595 shift registers and DS1307 RTC IC. As amplifier I chose TDA7052 because of low cost and almost no component. But you can choose any amplifier for it. To react function keys you need to press and hold keys and remember to put 100-330 resistors between shift registers and displays if those are too bright.

This built in some events and according to it clock change its welcome massage and alarm tone.

The events are;

• New Year – Jan 1  
• Vesak  - May 
• Christmas - Dec 25
• Valentine – Feb 14 and
• Birthday - User Define

You can add custom date for birthday by changing the values of Eeprom (1) for day and Eeprom (2) for month. Also used hex value for this.
Ex: for Jun 25 -> Eeprom (1) = 19 and Eeprom (2) = 06

LED Matrix Clock Preview

Tested and Working!

Matrix Clock

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