Projects on hold

Hey guys, I had to put the amplifier projects on hold, because there is a kind of a competition happening, which is going to take place in my university at the end of may. And I am prepering probably my most complex project yet, which consumes a lot of my time, because it is not ready yet and I really want to participate :D That is why I haven't posted anything lately :D So see you after may :D

And here are some potatos for you:

TDA7377 audio amplifier with baxandall tone control

Well I finally finished the first circuit of my amp :D The final circuit is here:

Here are the simulations of the baxandall tone control part. The first picture shows how the low frequency amplitude changes after passing through the tone control when the pot is turned to max and min bass :)

And here you can see what happens when you twist the treble pot.

Note: The frequency range in there pictures is logarithmic (Means the range is increasing with acceleration). So it may seam that the bass pot is effecting a wider range, but it is not.

Now for more detailed explanation, here is the same, but divided circuit:

YELLOW - this part helps the audio signal to get in the circuit. Mostly because of the impedance differences. The resistors values should be higher than 10K. This part is not necessary and has a con because it may bring more noise into the audio signal.

RED  - this is the one and only (well there are actually two of them in the circuit) the baxandall tone control circuit. By adjusting the pots you can change the low or high frequency amplitude, it works like an adjustable filter. And another thing about this part is that I have made an ACTIVE baxandall tone control, which means that this part requires a power source, but for that the passing signal doesn't lose strength. You can make a passive one by just removing the op-amp at the end of the red block circuit, but then it will lose about 20dB of signal power.

GREEN  - this part is the volume adjustment, you can simply put a pot here. But you can also add a resistor just before it, it will limit the max available (so the speakers wouldn't blow out and sound clear at maximum volume).

BLUE - this part is required if you are feeding this circuit with a single polarity power source, which means for example +12 and GND. This sets a level at the op-amps non-inverting input. Otherwise and actually even better if your feeding the whole circuit with a bipolar power source (+12, -12, GND). To do this all the op-amps will use +12, -12 as power source only the amp will still be running on +12, GND (mainly because TDA7377 operating power limit is 18V, so if you will give it +12 and -12 (sum is 24V) you will probably burn it). If the power source is bipolar all the non-inverting op-amp inputs should be grounded.

And what is left is the amp itself, the circuit is from its datasheet. If you do not need (or do not want the awesome baxandall tone control) you can apply the audio signal straight to the ports "IN LEFT" and "IN RIGHT" :)

Now just to build a box for this project and it will be completed :)

Power supply family

I remebered that I forgot to post the power supply that I remade from a PSU supply :) awesome useful thing :) And easy to make :) Here are the pictures :)

First opening of the cover:

Banana connector socket installation:

After removing all the unnecessary wires and leave only one wire of each voltage (+12V, -12V, +5V, -5V, 3.3V) and ground. And installed a switch simply to turn it on or off.

 After soldering the wires to the sockets.

Made this dielectric plate and installed it just below the sockets from the inside (so in case something happens to the wire it would not damage the circuitry below).

The final look is here :) There are red and green LED's glowing from the hole (red means that it is pluged into the wall socket and the green means it is turned on).

The supply can give 12V with 8A, -12V with 0.5A, +5V with 18A, -5V  with 0.5A and 3.3V with 8A :)

And the new member to the power supply family is the TOROID :D This fellow will power the new upcoming audio power amplifier :D It has 360W of power and can produce a bipolar source with +/-36V and 10A of current, but after leveling the output (with a diode bridge and big ass capacitors) it should theoretically jump up by a coefficient of square root of 2 which is 1.414.  
36V * 1.414 = 50.9V!! :D That much voltage should be more than enough :D
 Here are the photos of the guy:

This guy weights over 3Kg :D Damn... :D 

P.S, I have already made the circuitry for the TDA7377 the only probelm left is that I am trying to move it from a bipolar power source which is the PSU above to a simple DC adapter :) So I have to adjust the op-amps a little :)

Awesome tubes

okay, I did not make this, but this is f*cking awesome. Maybe one day I'll look in to it :D Couldn't help my self to posting it here :)

Sneak a peak, upcoming projects

The upcoming projects will include TDA7377 and LM3886. The TDA7377 project is gonna be an audio amp for my old speakers and the LM3886 is gonna be more interesting, because not only it is gonna be like 4 times more powerful audio amp, but will also include, a modified pair of speakers which will be remade into a passive 3-way speakers. It means that 3 speakers will act as one with a wide band. And I am gonna add some LED strips to it :)

Now I am working on TDA7377 project :) Photos:

TDA7377 Cooling, heatsink from an old PC CPU

TDA7377 Cooling, heatsink from an old PC CPU

 Basic stereo circuit form the datasheet to check the IC

Old S30 model ~35W speakers for the TDA7377

The finishing line of the project TEA2025 + LM3915

I just finished this little project. I actually finished a week a go, but did some finishing touches to the circuit these last few days. The circuit has a volume control and the LED high reference control (using the pot's). I didn't make the LED brightness adjustment, because the light was just fine by me (if you feel the need you can add it by adding the extra pot on LM3915). The TEA2025 did a much better job than the LM386 as expected, but as I was finishing this project, I have to say it is still pretty weak. You can listen to them but don't expect a good punch without hearing atleast a little noise (The power limit of the TEA2025). You may get a better resault than me if you get a decent speaker, mine was used and as I later found out crappy as ....

So without say any more, here is the circuit:

And the video result:

http://youtu.be/wCjnDwTiAwM


And the remake of this projects title will be posted next week, when I will get more info about it, so I could tell you more about it than just the idea.

By the way the transistor line at the LED's is not necessary, I was planing to put LED strips then you would need the transistors (the LED strips would go instead of the LED's in the circuit), if you only want 1 LED per level than connect them like this, in the picture:

TEA2025 (remake of part 1 for the the equalizer project)

Compared to LM386, TEA2025 really blew me away. The amplification was much bigger and that helped to keep the quality of the sound smooth. Had little trouble with because for me the chip on the proto-board was very sensitive to any longer wires, so I had to compres everything as much as possible after that it started to give out clean sound. The circuit is from the datasheet "bridge application".

Datasheet:
http://www.st.com/web/en/resource/technical/document/datasheet/CD00000172.pdf

And the one and only, my test video :) Enjoy :)

LED equalizer update (LM386 not good)

Hey, I've read a bit more about LM386 and it seams, that it is too weak, to drive a bigger than a speaker for headphones (or you'll gonna get bad quality sound) which in my case, I did. I could'nt figure out why was it so bad especially with increase gain. So the lesson of today is - if you want to use a normal speaker >1W use a stronger Amp, in my case I am going to try TEA2025. While LM386 output power was between 250 - 1000mW (depends on which model you're using), the TEA2025 can give out 1.5W on 6V and 4.7W!!! on 9V (for 8Ohm speaker). I'll post some resultes after I get it, tomorrow :)

LED equalizer update

Hey, I had some spare time, so I moved further with this project and I think I am at the end of it :D The equalizer seems working and the sound is clear enough (Need to test it with a not crappy speaker) :D

Here is the result:

To be continued.

The audio EQ (part 1 LM386)

Hey, the first part is done. I made a audio amp with LM386 (it is kinda similar as the my previous circuit LM386 + MIC) it uses a 3.5mm audio input jack (tested it with a phone and PC) and as output a crappy speaker (planing to get a decent one for the finishing).

So far the schematic looks like this (PDF):

https://www.dropbox.com/s/fu7xfdqfm15psxo/Equalizer.PDF?dl=0

• The Resistor (R4) doesn't have a value because it depends on what kind of a speaker your hooking. The values are in the LM3915 datasheet (26 page).
  http://www.ti.com/lit/ds/symlink/lm3915.pdf
• My schematic has a bass booster (it is not necessary)
• The gain is 20, you can increase it by attaching a cap between 1 and 8 pins of LM386. The details are on LM386 datasheet http://www.ti.com/lit/ds/symlink/lm386.pdf

From now on I am using Altium designer for schematics or Multisim for simulations.

As usual here is the photo of the first part working.
I didn't have any 220uF caps with bigger that 10V, so I used 1000uF :D I'll get some later :D

And a video (I should start talking in the videos :D wouldn't look so creepy):

https://www.youtube.com/watch?v=Id92W70uvvI