Introduction: Tone Volume Ballance Control Circuit. Overview.

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About: I am a University of Edinburgh electronics engineering student.

I decided to do this audio project as it is interesting by means of learning something new, expanding my knowledge and of course I wanted to control the music between its source and the speakers.

The circuit is based on LM1036N which is a DC controlled tone (bass/treble), volume and balance circuit for stereo applications in car radio, TV and audio systems. An additional control input allows loudness compensation to be simply effected.

All you need for this project is the LM1036N, 15 capacitors, some fixed resistors and some potentiometers. The result is a high quality control circuit that is small, energy efficient, easy to make and enhances your audio listening experience.

Step 1: Step 1: Research

The circuit I used is from the manufactirer's data sheet.
http://www.ti.com/lit/ds/symlink/lm1036.pdf

Take a look at page 6.

Without making any changes, the circuit performs just great, so if this is your first circuit - do not hesitate to build it - it will work if you don't mess the components!

The components that you will need are as follows:
  • LM1036N
  • 47uF x 1
  • 0.47 uF x 2
  • 0.01 uF x 2
  • 0.22 uF x 4
  • 0.39 uF x 2
  • 10uF x 2
  • 10nF x 1
  • 47k resistors x 4
  • 47k potentiometers x 4
  • switch x 1
  • a 3.5 mm audio female and male jacks (could be any size jacks)
  • some cables (use shielded for the input and output signals)
  • an empty board that you will solder on
  • soldering and wire cutting tools
  • plastic enclosure
  • knobs for the potentiometers
Summing the money spent, the circuit costs around 15 EUR.

Step 2: Step 2: Experiment

So I started by building the circuit on a breadbord. This is convinient if you are making it for the first time and not sure what the result will be, but do not trust the simulations!

When I was doing tests the overal performance was rather week and there was a lot of noise in the audio signal. You can skip this step and go on to solder all components if you are sure it will be ok.

I should mention that for the input signal first of all I use my fingers. Toching the input leads of the jack (left & right channels) must produce some bad noise. Try turning the volume potentiometer all the way to maximum. If you don't hear noise, you better not hook up your phone and investigate the circuit - maybe there is a short circuit or something is connected the wrong way.

NOTE: All electrolytic capacitors have to be wired the correct way. They all have markings on one of the sides (most commonly the negative side) and take some time to investigate this!

After I heard the noise in both channels, I hooked up my phone to the input and played some music. Test all knobs and see the difference in the music.

Another point to mention is the output signal. I have used some standart headphones to listen to the output. If you use speakers, you will be able to differentiate the low and high tones very precisely, but in case you use some headphones from your oldest kasette player you won't be able to see the real difference in the tone settings.

Step 3: Step 3: Build the Circuit

Here on the first photo I have soldered most of the components. Try and put the capacitors as close to the chip as possible as this will shorten the tracks length and minimise noise. This also helps when choosing the enclosure as it can be smaller and the pcb will fit easier.

The second photo shows the circuit finished cut, with the output cables soldered from the botom side. Yellow and Red are the channesl and shield is the ground.

On the third photo you can see the tiny input cables. These actually come from an old set of headphones which is good as the 3.5 mm jack is already there and there is no need to solder it.

Step 4: Step 4: Get the Enclosure

You will probably want to put the potentiometers on one side of the box you use. I have used a plastic enclosure that is just the minimum size for my pcb. I drilled four holes on the front to put through them the potentiometer's shafts. All potentiometers are tightened on a small plastic piece inside the black enclosure.

I used short jumper wires to connect the potentiometers.
NOTE: Two of the three potentiometers' pins run in parallel, so you can save some wires by making bridge-like wires.
:)

Step 5: Step 5: Enjoy

Finally fit all the things in and power the tone controller!

I use regular 12 V DC supply from a car lighter because this tone controller is in my car and I have no jack to the output cable as it goes straight to an amplifier.

Wish you success in building this circuit!