Introduction: PC Speaker Amplifier

This is small power (Less than 10Watt) transistor amplifier using LM386 and TIP41/42.

Although output power is non a lot baronial, still it can well serve as an amplifier for Microcomputer speaker and MP3 player.

When living in a packed flat jointly, a half output power from this amplifier easily produce complains by my family.

Anyway, it can ram down 8ohm and 4ohm speaker with maximum 12V power supply.

I got the original schematics from the website (hypertext transfer protocol://www.bristolwatch.com/radio/lm386_power_amp.htm, Lm386 Audio Amplifier Adding Push-Pull Output Stage).

As the circuit not using dual polarity (+/-) power supply, overall circuit complexity is not much high and compact size (15cm(W) x 10cm(D) x 5cm(H)) of chassis can be used as shown in the picture to a higher place.

I had made several amplifiers with original schematics and the one of them shown in the picture above is the final version which applied slight modifications from the original.

Step 1: Late Amplifier Version

This is old interlingual rendition of amplifier made according to the original schematics.

IT use TIP31/32 transistors as push-pull production represent..

I'm using common LM7812 potential difference governor electric circuit and 220V(in)/15V(KO'd) wall adaptor as power supply because the amplifier tour requires to a lesser degree 1A contemporary during normal operation.

Information technology's quite gratifying atomic number 3 output raze is adequate enough to labor whatever of 8ohm or 4ohm speakers I feature.

Sound quality is besides reasonable when comparing with commercial audio frequency amplifier I used before.

But it seems a high frequency noise is coming out when hearing close to a speaker.

Maybe LM386 amplifier IC seems to produce high relative frequency of hissing noise together with normal amplified audio signal.

Therefore, this amplifier is not frequently used as hearing several hours unremarkably make water me uncomfortable due to the high frequency healthy coming impermissible from a speaker.

And sometime Unq (radiocommunication frequency) abound pickup happen when motorbike is passing by near my flat with big disturbance.

***

I had searched internet to reduce high pitched hissing and occasional RF pick-me-up on the whole.

The schematic below is the outcome which is applied with some modifications recommended in respective web-pages.

Step 2: Circuit Schematics

As I'm not good at analogue electronics, a scientific explanation is not possible for the modifications I made in the schematics above.

But result is quite an satisfying when I'm listening MP3 playing and auditory sense audio output of videos for various hours with modified circuit of amplifier.

As audio quality is very personal affair according to a ain viewpoint, the remedying actions above will non be eligible to somebody.

But anyway no longer RF pickup and also high pitches of troublesome noise is disappeared finally.

The reasoning of the addition and removing of electronic components are as follows.

***

- Applying low (100uF) and high (0.1uf) frequency bypassing capacitors are recommended to the power supply line of LM386 to take away noise inlet to the amplifier IC

- Reducing gain of LM386 (piss open pin 1 and 8 to fix gain as default 20(26dB)) help to remove heights frequence noise is besides recommended in unusual network-pages.

- And at long last add one many instrumentality condenser (0.1uF condenser which is numbered Eastern Samoa 3 in the schematic above) to LM386 output is claimed for removing any high pitch noise birthday suit atomic number 3 the ceramic capacitor is acting arsenic low pass filter

***

Complete supra recommendations I found in web-pages are applied and tested individually to bring out the final schematic shown in the picture above.

Firstly, I don't think the combined more supplement of ceramic electrical condenser (number 3 portion in the schematics) to LM386 output as respectable idea.

Because possibly the condenser Crataegus laevigata remove some of useful high frequency audio signal from the speaker output is very commonsensical suspicion for anybody.

Merely the capacitor increase becomes quite a effective solvent to remove RF pickup and high pitched hissing sound from audio output in the end.

Step 3: Wiring Drawing

As stereo output is required, 2 amplifier circuits are positioned and wired happening linguistic universal PCB board.

When comparing schematics and wiring plot jointly, you can encounter apiece wiring depicted in the schematics is matched with wiring normal in the draft above.

Similar sizing of each electronic component is depicted, located and wired together with other components in the wiring draft.

To reduce overall wiring length, non oblong and slanted wiring figure is victimized.

And orange colored lines are bugged and machine-accessible on the top of PCB.

Meanwhile other red/party biased lines are tense and connected at the back(bonding) side of PCB.

Step 4: Parts

I can't depict and explain each component one by one in the picture above.

Merely the most of note honored components are described in the picture.

The detail BOM (Bill of Materials) is represented in the list below. (Price of only important ingredient is written. But the cost information is provided even as mood)

***

- LM386 amplifier IC x 2 (Or so 1$)

- TIP41 (NPN transistor) x 2, TIP42 (PNP electronic transistor) x 2 (About 1.2$ for each)

- 1N4148 diode x 4 for biasing transistors as Class Artium Baccalaurens

- LM7812 voltage regulator (Amplifier power supply)

- ALPS dismal velvety 20K potentiometer (Volume control, dual 20K VR included, 10$)

- 1000uF electrolytic capacitor x 2 for filtering DC from audio output

- 100uF electrolytic capacitor x 2 for bypassing low frequency haphazardness from power line of products

- 10uF electrolytic condenser x 2 for bypassing power with LM386 IC

- 2.2uF electrolytic capacitor x 2 for coupler audio input signal to amplifier circuit

- 0.1uF ceramic capacitor x 6 for power filtering and high frequency noise suppression

- 0.33uF film capacitor x 1 for LM7812 regulator noise filtering

- 0.047uF film capacitance x 2 for output stabilizing (Zobel network)

- 2.2ohm 1/2W resistor x 4 for junction transistor loading

- 1K 1/4W resistance x 2 for junction transistor biasing

- 10ohm x 2 for output stabilizing with Zobel net

- Speaker cable wiring terminal block (4 Pins, 3$)

- 3.5mm stereophonic system sound input socket

- Bill power recess socket for 15V wall climb down power supply adaptor

- Adaptable PCB board about 15cm (W) x 10cm (D)

- Acrylic fiber board x 4 (15cm (W) x 10cm (D) x 5mm/3mm (H))

- Metal supporter M3 size (bolt/testicle) 3.5cm x 4

- 2 wire cables (rating 5V and more than 2A)

***

Transistor matching is recommended in the web-page where the original formal is posted.

For better audio quality, usually transistor matching is required for supporting identical physical characteristics of NPN/PNP transistors.

Simply as matching cognitive process is a little bit tricky, I will not mention details in this story.

Step 5: Wiring and Soldering

Tin wires (AWG 24 size) are used for making wiring patterns as depicted in the schematics and wiring drawing.

Some jumper cables are used attributable the mistakes made during soldering.

As soldering method acting is excuse in new instructable (https://www.instructables.com/circuits/raspberry-pi/projects/recent/), I will not describe details in this story.

But basically wiring and soldering is performed according to the details equally shown in the wiring drawing.

As seen in the picture above, various cables are connected to the amplifier including much as stereo sound cable, 2 wire speaker cables and 15V power supply cable television.

Ill-use 6: Playing and Boost Growth

As amplifier making is finished, lease start to listening whatever music with it.

The speaker shown in the impression above is Scandyna MicroPod SE which was bought active 10 days past.

Now sound cable connector model is exchanged into Bluetooth and still the same shape of manikin seems available for purchasing.

Personally I'm supposing the speaker unit's commercial specification and performance is more important than amplifier for audio quality.

The speaker's technical specification is as follows.

***

- Applications Hawaii-Fi stereo, AV-Base Theatre systems

- Amplifier requirement 10 - 100 watt

- Minimum ohmic resistance 4 Ω

- Frequency Response 65-20.000 Hz (± 3dB)

***

I represented the usage of this amplifier for PC speaker.

Just IT can be interfaced with diverse audio sources for playback music or telecasting.

You can perspective the television of the amplifier operating in the favourable connectedness.

*** <Video Link>

https://drive.Google.com/file/d/131MuCqJzu-P7cf5pM...

***

As recording is performed by smart-phone, audio upper-class is not much recognizable.

Anyway I'm using this amplifier as basic gimmick for playback any multi-media contents with PC , Raspberry PI server, forward-phone and and then on..

Equally an extension of this project, some minimal brain dysfunction-on functional will cost coeducational to this amplifier.

Thanks for reading.

Be the First to Part

Recommendations

  • Anything Goes Contest 2022

    Anything Goes Contest 2022