Baxandall Tone-Control Audio Amplifier

This circuit exploits the high slew rate, high input impedance, and high output-voltage capability of CA3140 BiMOS op amp. It also provides mid-band unity gain with standard linear potentiometers.

 Baxandall Tone-Control Audio Amplifier

Race-car-motor-crash

The mixer can be multiplexed between the SLF and VCO functions. 

For two simultaneous race-car sounds.

How to Build a Subwoofer Box

Building a subwoofer box is the foundation of your new car audio system . In this video I will show you different techniques that will make your sub enclosure perfect and help it sound even better!

How to Build a Subwoofer Box

300W Building a subwoofer enclosure

This is how a subwoofer enclosure is built, it is ported and is tuned to 35hz the subwoofers that i am installing are 2 re 8's that are dual voice coil and i am pushing 300watts at 4ohms.

300W Building a subwoofer enclosure

7 segment display Arduino

The aim of this article demonstrate how the Arduino can run on 7-segment display. We used a SA56-11GWA which is a single display with common anode, it means that the anode is common to all digits, and to the point.
A display consists of 8 LEDs, 7 form the figure and 1 point decimal.A conversion between decimal and what we intend to show the binary information that you receive is called the BCD (Binary Coded Decimal).

In terms of hardware, each LED work individually, so each of the segments has to lead a limiting resistor, in this case, each digit has an operating voltage of 2.2V and consumes 20mA. If the voltage is 5volts, we need the resistor fall 5-2.2 = 3.8V, by Ohm's Law we can calculate, R = V _res / I _led R = 3.8 / 0.020 = 190 Ω +/- 20% (let's use a resistor with 220Ω). This applies to this display SA56-11GWA used as an example, other values ​​may be different, it is useful to calculate the required resistance value.

Decimal	The	A 3	A 2	A 1
0	0	0	0	0
1	0	0	0	1
2	0	0	1	0
3	0	0	1	1
4	0	1	0	0
5	0	1	0	1
6	0	1	1	0
7	0	1	1	1
8	1	0	0	0
9	1	0	0	1

The first thing we have to do is convert our decimal number to binary, we will use examples only 0-9 this first phase

 decToBcd byte (byte val)
 {
   return ((val / 10 * 8) + (val% 10));
 }

This makes our decimal value to binary, for example, assuming that have numbers with more than two digits, 27 will be 0010 0111 (2 - 7 BCD). If we have only one figure 2 for example, will have 0010.
This allows us to act on an IC decoder (4511) and the use of only four BCD outputs Arduino, so can convert a result of a count value, or for any input digit.

 / *
 Example of a counter from 0 to 9 that adds each 
 Since there is an entry in A0
  
 author: Arturo Guadalupi 
  * /
 
 // Declaration of pins used in the 4511 entries
 The const int = 2;
 const int b = 3;
 const int c = 4;
 const int D = 5;
 
 void setup () {
   pinMode (A0, INPUT);
   pinMode (A, OUTPUT);  // LSB
   pinMode (B, OUTPUT);
   pinMode (C, OUTPUT);
   pinMode (D, OUTPUT);  // MSB
 
 }
 
 int count = 0;  // Used for the variable number
 
 void loop () {
   if (digitalRead (A0) == LOW) // if the button is pressed on the A0 input
     {
     count ++;
     delay (200);  // The delay prevents multiple counts
     if (count == 10) // 0-9 counter
       count = 0;
     to_BCD ();  // Convert to binary
     }
    
   if (count == 10)
     count = 0;
   
 }
 
 to_BCD void ()
 {
     if (count == 0) // write 0000
     {
       digitalWrite (A, LOW);
       digitalWrite (B, LOW);
       digitalWrite (C, LOW);
       digitalWrite (D, LOW);
     }
     
     if (count == 1) // write 0001
     {
       digitalWrite (A, HIGH);
       digitalWrite (B, LOW);
       digitalWrite (C, LOW);
       digitalWrite (D, LOW);
     }
     
     if (count == 2) // write 0010
     {
       digitalWrite (A, LOW);
       digitalWrite (B, HIGH);
       digitalWrite (C, LOW);
       digitalWrite (D, LOW);
     }
     
     if (count == 3) // write 0011
     {
       digitalWrite (A, HIGH);
       digitalWrite (B, HIGH);
       digitalWrite (C, LOW);
       digitalWrite (D, LOW);
     }
     
     if (count == 4) // write 0100
     {
       digitalWrite (A, LOW);
       digitalWrite (B, LOW);
       digitalWrite (C, HIGH);
       digitalWrite (D, LOW);
     }
     
     if (count == 5) // write 0101
     {
       digitalWrite (A, HIGH);
       digitalWrite (B, LOW);
       digitalWrite (C, HIGH);
       digitalWrite (D, LOW);
     }
     
     if (count == 6) // write 0110
     {
       digitalWrite (A, LOW);
       digitalWrite (B, HIGH);
       digitalWrite (C, HIGH);
       digitalWrite (D, LOW);
     }
     
     if (count == 7) // write 0111
     {
       digitalWrite (A, HIGH);
       digitalWrite (B, HIGH);
       digitalWrite (C, HIGH);
       digitalWrite (D, LOW);
     }
     
     if (count == 8) // write 1000
     {
       digitalWrite (A, LOW);
       digitalWrite (B, LOW);
       digitalWrite (C, LOW);
       digitalWrite (D, HIGH);
     }
     
     if (count == 9) // write 1001
     {
       digitalWrite (A, HIGH);
       digitalWrite (B, LOW);
       digitalWrite (C, LOW);
       digitalWrite (D, HIGH);
     }
 } 

Convert decimal to binary (8bit)

It is possible to directly transfer the binary value for the exits, here is an example of cyclic counter zero to nine

 ledpins int [] = {4,5,6,7,8,9,10,11};
 byte digits [] = {B11111100, B01100000, B11011010, B11110010, B01100110, B10110110,
 B10111110, B11100000, B11111110, B11110110};

 void setup ()
 {
   for (int i = 0; i <8; i ++)
   {
     pinMode (ledpins [i] OUTPUT);
     digitalWrite (ledpins [i], HIGH);
   } 
 }


 void loop ()
 {
   for (int i = 0; i <10; i ++)
   {
     displayDigit (i);
     delay (1000);
     AllOff ();
     delay (500);
   }   
 }

 displayDigit void (int digit)
 {
   for (int i = 0; i <8; i ++)
   {
     digitalWrite (ledpins [i] ,! bitRead (digits [Scan], 7-i));
   } 
 }

 void AllOff ()
 {
   for (int i = 0; i <8; i ++)
   {
     digitalWrite (ledpins [i], HIGH);
   }  
 }

In this case not used the BCD outputs but a direct binary code in 8 bits (one for each connected LED)

We used a level 1 (HIGH) when the segment lights and 0 (LOW) when deleted. The last digit is always a 0 represents the decimal point that is not being used.

The AllOff () procedure off all digits reversing the common pin.

displayDigit () connects the right thread for each digit. The function bitread reads the bits of the binary number, starting with the rightmost bit.That's why the 7-i is used. When using the digitalWrite () statement, we can write 1 when we want to HIGH and LOW 0 when we want. This is the opposite of how our binary numbers are working. The operator! inverts the value. via electronica-pt.com

Preamp Circuit

Using a K-12 tube amp with a NAD C542 CD player, there is no need for a buffer or visit page. music which the K-12 does so easily. There was always something missing when it came to a convincing delivery. I felt a little of that beautiful valve warmth was required, so I tried a very affordable Valve Preamp kit from Silicon Chip Online. The preamp kit is based around a common 12AX7 dual triode. The line level (Hi-Fi) version of the kit has the gain set at 4 (6 dB). What makes this kit very inexpensive is that power comes a switch mode power supply, fed from a 17 volt DC wall wart!...
line level preamplifier. The K-12 is a very polite and sweet amp with all the warmth of it`s `hot bottle` heritage. However, when I compare the K-12 with my monoblock chip amps (LM3875), I was never convinced that the chips amps really delivered the passion of the

Electric Motor easy to make

A simple electric motor homemade, easy to make.

1. 1 meter of wire
2. magnet
3. one battery AA or AAA
4. Improvisation