make simple guitar amplifier An Incredibly Easy - under $5 bucks

One of the project I am currently working on is to make home made guitar amplifier run on 5 Volt USB power. It's very simple circuit based on TEA2025B amplifier IC in mono-output instead of the common dual output. Powered by 5 volt USB power it still produce quite a loud sound that you can expect. The only things that is missing from the circuit is the mixer variation like distortion, whammy and harmonic sound which will be done in future circuit. The basic sound is good enough to produce the loudness for acoustic guitar play at home with a small sub-speaker that you have.

Components:

1 x TEA2025B Dual Amplifier IC
2 x 470 uF @ 10 volt Electrolyte Capacitors
4 x 100 uF @ 16 volt Electrolyte Capacitors
2 x 0.15 uF Ceramic Capacitors
1 x 0.22 uF Ceramic Capacitors
1 x 10 kOhm Potentiometer
1 x Guitar Jack input port
1 x Edifier sub-speaker

How to make

Step 1: Assembly

Select electrolyte capacitors - it's best to choose capacitors that is rated not more than 16 volts because the circuit only run on 5 Volt power supply. Although 25 volt is still good enough but best to have it within the range of 10 volt to 16 volt because it is no harm to the circuit. And i believe it's very efficient. The ceramic capacitors voltage is no problem but in this case I have used with the rating of 50 volt even 1000 volt is fine i guess.

Try to assemble the circuit components as closed as possible to one another to reduce the amount of resistance and it will reduce the noise within the circuit as well. As you can see the video the circuit is very compact as the components are soldered very closed to one another.

Remember that pins 4, 5, 9, 12, and 13 despite to all of them need to connect to the ground but it actually very inefficient if you connect them separately to the ground connection. So the best is to use a jumper wire to join 12 to 5 and 13 to 4 then join 12 to 9. Remember that pin 12, 13 is the first amplifier ground in the IC and pin 4 and 5 is the second amplifier ground. Pin 9 is the sub-ground. So once those ground is connected you can put the negative power supply either on pin 12 or 13 and it will flow down to the rest which means it goes one way rather than each individually connected to the negative which can cause bad noise.

Boot.1 and Boot.2 connected to Output.1 and Output.2 respectively using 470 uF @ 10 Volt electrolyte capacitors in this case using TBOR capacitors. On the output pin 15 and 2 join to ground using 0.15 uF ceramic capacitors in this case 5 volt to reduce noise effect.

First feedback pin 11 is join to ground using 100 uF electrolyte capacitors and second feedback on pin 6 join to bridge on pin 1 using 100 uF electrolyte capacitor. Pin 8 SVR goes to ground using 100 uF electrolyte capacitor. Pin 16 is connected to power positive and connected to ground via 100 uF electrolyte capacitor.

Pin no.10 is connected to the middle pin of the 10 kOhm potentiometer (variable resistor) via 0.22 uF ceramic capacitor. Then right pin of the potentiometer goes to the guitar positive input while the left pin goes to the negative (ground) of USB 5 volt power supply.

Refer to the TEA2025B internal infrastructure of the IC



Step 2: Testing the sound

You might hear unwanted noise if the sound is played even with guitar. If that happens you may use 330 Ohm resistor connected parallel with the 0.22 uF ceramic capacitor at the output connected between the potentiometer and pin 10.

See the guitar amp schematic diagram below



Hope this helps...let me know if you have questions!!

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