This is not so complicated Amplifier that could be use in household or in the cottage or anywhere where you think off.

This is upgraded version of my first instructable "Amplifier TDA2005" . Basically this small amplifier was originally created like low cost solution for my cottage near the Danube, but after connecting it with some old HiFi speakers i decide to keep it and with some improvements use it as good audio systems. Probably the old audiophile will say that something that is based on TDA2005 cannot be consider audio system, but after lots of hours spended listening to this small beast I am pretty pleased with the quality.

My personal opinion is that good audio system is the system that you could listen for hours and that the sound is not irritating for you, for example during the nap.

Step 1: Component List

1. 3V-12V Audio/ Video Signal Monitor

http://www.ebay.com/itm/3V-12V-Audio-Video-Signal-...

2. Speaker Protection Board

https://www.aliexpress.com/item/Speaker-Protection...

3. Transformer 230 V / 12 V - 10 A

4. Amplifier TDA2005 (I have salvage mines from old car CD player but they could by bought on ebay)

5. 1 x Diode bridge >10A + 1x diode bridge 1,5A

6. Capacitor > 50V min. I use (2 x 4700uF + 2 x 1000uF) for amp power supply + 1 x 1000uF for control board

5. Knob + potentiometer with push button (I have managed to salvage one from old car CD player )

6. Gillette gift box :) (or something similar)

7.Transformer 230 V / 12 V - 1,8 VA

8. Transformer 230 V / 9 V - 1,8 VA

9. 3 x Signal Relay HK19F-DC12V-SHG

https://www.aliexpress.com/item/Free-shipping-5PCS...

10. Relay 12VDC /10A

11.Texas Instruments MSP430G2211 micro controller

https://www.ebay.com/itm/5PCS-X-MSP430G2211IN14-IC...

12. Small electronic (resistors, IC, capacitors - based by the schematic )

13. Input 3 way cinch connector

14. Speakers terminals

15. AC conector input (from old ATX PSU )

16. Fuse and fuse holders on the power input

17. Walnut wood 150mm x 400mm

18. RGB diode (check out the photo )

19. Wires

20. Cooler for TDA2005

Tools :

Soldering iron
Texas Instruments Launch Pad MSP430G or Arduino (but have to change/adapt schematic and code (code is basically the same only the names of the pins are different))
Program Energia by TI or if you use arduino
Hardware (electric drill , and something to cut metal plate and cut wood)
finish for the wood (brush and gloves)

Step 2: Schematic and PCBs

In the schematic you could see that I have used 3 transformers, maybe it look silly but it is not.

First trafo 230V/9V/1.8VA is used as a standby trafo for control unit, second trafo 230V/12V/10A is power trafo for the amplifier, and the third one 230V/12V/1.8VA is used as a power source for speaker protection PCB, this circuit is demanding separate powering (I tryed to use main power trafo but there was noise in the speakers). Standby trafo does not provide enough juice for powering two relays on speaker protection board.

MSP430G2 is power with 3.3VDC that is the main difference between ATMEGA328-168 and it has inside crystal, so that stand alone application is managed with only one resistor 10K.

PCB are made by Toner transfer and etching method, pcb is design in free program ExpressPCB, file is available for download, after everything has been solder together I use plastic spray for isolation PCB.

PCB for TDA amp. Is downloaded from here:

http://electronics-diy.com/electronic_schematic.ph...

and

http://www.learningelectronics.net/circuits/low-co...

All of the PCBs are mounted in the housing on plastic stands

Step 3: Box - Housing

Design of the box was limited to the gift box that I have find lying around in my house.

It is not very solid box so I had to make some wooden frame.

Front and back panel is made from walnut board and painted with lacquer. As you can see on the photos back board is thick and the input connector need to be mounted on the control unit PCB, because of that I have first drilled with fi15mm only to the certain depth and afterward finished the hole with fi11mm auger.

As stands I use kitchen drover handle from IKEA (it cost 1€ for the 4 handles)

Top of the gift box was made with transparent film, this was not the best solution because I need ventilation for the amplifier cooler. At the hardware store I bought metal galvanized mesh, i have cut it precisely to fit top of my housing , and it looks very nice. Thru the mesh you could see inside of the amplifier that way I came up to idea for internal lighting which will also indicate the input channel that is in use

Step 4: Programming and Features

This amplifier is custom made for my purpose in my flat. At my living room I have 3 music sources PC, TV and AUX (cellphone or tablet).

Electric installation in my flat is design in the manner that when TV is off it is not on standby (saving the planet) but smart installation is cut the power of, it is the same for this amplifier (TV and Amplifier are not in the same power socket, TV and Amplifier could work independently), Activating amplifier socket is done remotely thru cellphone or by remote or by wall switch, it is little complicated to explain but this will be explain in the some other instructable.

I have add three videos from youtube for easier understanding of input selection

AUTOMATICALLY CHECKING INPUT

Thanks to the Audio detector I add few other features to the control unit, when the amplifier is powered on, control unit activate PC input and is checking is there an active signal, if there is no signal for 1,5s it deactivate PC input and activate TV input, if there is no audio detection on the TV input it deactivating TV input and activating AUX input , if there is no audio input on the AUX input it stays in the standby mode. Oppositely if the audio input is detected, the power transformer is activated and speaker protecting board smoothly activate the speakers output.

So brief explanation.

if PC = active

amp is ON

else

if TV = active

amp is ON

else

if AUX = active

amp is ON

else

standby:

POWER SAVING MODE

Also the audio detector is checking time without input signal into the amplifier, if there is no input signal for more than 90s Amplifiler it going standby, after input signal is detected it automatically start the amplifier on the input channel that was previously active.

ONE BUTTON CONTROL

I decide that only one button should be enough for input selection. If the amplifier is in standby mode pushing the button activated amplifier, after the activating amplifier you can chose input by pressing the button. Each input channel is marked with one color of the RGB leds , PC is blue , TV is Green and AUX is Red.

kode_okt_22_2017.txt
Download

Step 5: Wiring

After placing and mounting components in the housing it is time for the wiring game. I always prefer to use exact necessary length for the wires and twist the paired ones, somebody would say that it could be done better but wth wires that I had at my disposal it is not bad,

Make sure to use shield wires for input signal because of possible noise on the input. Also have in maid that amplifier is drawing lot of current so please use adequate wires.

Speaker terminals are soldered directly on speaker protection pcb.

Ass a resistor that limit the current of the RGB (check the last photo), I have used 3 x 4K / 0,25W in parallel connection which gives (4K / 3 = 1,33K / 0,75W)