Dilshan R Jayakody’s Web Log

The LM386 is a low-voltage audio power amplifier designed by National Semiconductor , which is now part of Texas Instruments . Introduced in 1983, it has been widely used in various audio applications, such as amplifying signals in small radios, portable speakers, and other low-power audio equipment. This compact device integrates all the essential components of a basic audio amplifier circuit, including an internal biasing network, an input stage, and an output driver. It operates within a supply voltage range of 4V to 12V, making it ideal for driving small speakers while consuming minimal power. A standout feature of the LM386 is its adjustable gain, which can be varied between 20 (26dB) and 200 (46dB) using external components. Assembled LM386 power amplifier. Although modern Class-D amplifiers offer higher efficiency and greater power output, the LM386 remains a viable solution in certain applications due to its straightforward design, low cost, ease of assembly (thanks to i...

TDA7052A is an audio power amplifier designed for use in low voltage battery-powered equipment. Compare with the popular LM386, TDA7052A is not so popular among DIY electronic enthusiasts.  Final view of the finished amplifier with speaker.   Using the Bridge Tied Load principal, this IC delivers an output power of 1.2W into an 8Ω load with, 6V power supply.   The most striking feature of this amplifier is the minimum external component count. This IC only needs two external capacitors to build a functional audio amplifier.   The gain of the amplifier is fixed internally at 40dB. The amplifier got, short-circuit protection, requires no external heatsinks, and not producing any switch on/off click sound(s).    Although this is an old amplifier IC, it is still available to purchase in many local and online stores. Compare with the other low-power AF power amplifier ICs, TDA7052 is a little expensive in the local market. Although it is costly, I use this IC ...

This is quick (and final) post regarding our Mullard 3-3 audio amplifier project. In the last few months, we got several e-mails regarding this project and most of the people are asking for modified schematic related to this project . The schematic of our amplifier is available to download in here . Please note that this schematic is heavily based on the original Mullard 3-3 amplifier design and the main component which we replace in that original schematic is its tube base power supply unit. As a final step of this project, we construct a wooden enclosure for that amplifier and attached it to 10 inch (8Ω) full range speaker. High-resolution photographs of our amplifier are available in here . Final view of Mullard 3-3 audio power amplifier As a conclusion, this Mullard 3-3 audio power amplifier is a high-quality low power tube amplifier with minimum complexity. We really impressed with its audio quality and overall performance.

Mullard 3-3 is quite popular 3W tube amplifier introduced by Mullard Ltd in 1956. A schematic and design detail of this amplifier is available in " Mullard Circuits for Audio Amplifiers " book and in National Valve Museum article . This amplifier is based on EF86 , EL84 vacuum tubes, and EZ80 full wave rectifier tube. In this project, we decided to construct this original Mullard 3-3 Amplifier with some slight changes and commonly available electronic components. Top view of Mullard 3-3 amplifier with 6P14P and 6J8 tubes. In our prototype, we replace the EZ80 tube with 400V 5A bridge rectifier which is commonly available in many electronic spare parts shops. Also, we replace EL84 with 6P14P pentode and EF86 with a 6J8 pentode. Both of these valves can directly use with this circuit and those values are available for a lesser price than EL84, EF86 tubes.

SL414 is combined audio preamplifier and power amplifier IC manufactured by National semiconductors in early days. This amplifier is designed to operate in 10V to a 20V range and deliver 3W (R.M.S) audio output power into the 7.5Ω load. The frequency bandwidth of this IC is between 30Hz to 18kHz and with the 8Ω load, it produces 0.5% T.H.D on 3W. The most uncommon feature of this IC is its EP-10 package. This EP-10 package is common to most of the SL4xx series amplifiers and thanks to its inbuilt screw it is really easy to attach heat-sinks to these ICs. EP-10 package of SL414 audio amplifier IC. During our prototyping, we try several SL414 amplifiers and most of them give quite satisfactory results to us. Link to most stable SL414 design is available at the bottom of this article. As per our experiments, to archive best results it is mandatory to build this amplifier on PCB with screened wires. Also to get the good results to make sure to drive this amplifier with a regulat...

This article introduces high quality digitally controlled 2.1 channel analog audio power amplifier system. This project is mainly based on TDA7377 AF power amplifier and PIC18F452 8bit microcontroller. Basic features of this receiver are 2 × 6W + 20W audio output power, ±14dB bass and treble controls, fully configurable +35dB bass booster for sub-woofer and satellite speakers and loudness switch. This system use commonly available electronic components and all the integrated circuits are in DIL packages. This amplifier consists with few UI elements such as 2 push buttons and 1 rotary encoder. All the menu navigation can perform through rotary encoder. Prototype version of 2.1 channel audio power amplifier project Entire amplifier can build on 147mm × 80mm PCB and all the PCB design files are available to download at google drive . This is an open hardware project and all the firmware source codes, design files are covered with Mozilla Public License version 2.0 . All the ab...

This is our first vacuum tube base amplifier project and this project is based on 6AS5 pentode and 6N2P dual triode. Schematic of this project is not designed by us and we got it from web. We got this schematic sometimes ago and now we can't find original site where this schematic appeared first, because of that we host copy of that schematic in here . Prototype version of 6AS5 and 6N2P guitar amplifier In original schematic, initial stage of the amplifier is based on 12AX7 high gain tube. During the construction we can't find 12AX7 in local market and because of that we replace 12AX7 with 6N2P. Both 12AX7 and 6N2P had identical characteristics and only major difference is heater configuration. After replacing 12AX7 with 6N2P, both the tubes can drive through single 6.3V filament supply. 6N2P tubes are now commonly available and we use Russian version of 6N2P (6Н2П) for our testing. We test this amplifier with 4K audio output transformer and it produces excellent ...

This is high quality stereo digital audio amplifier with PLL synthesized FM radio receiver. Some of the high level specifications of this receiver are listed in below: Audio output power: 4W + 4W (with 8ohm speakers) Input sources: FM and 3 external stereo line inputs FM frequency range: 88.00MHz – 108.9MHz Supply voltage: 12V – 15V (2A current source is recommended) Tone control options: Bass, Treble and Loudness control Bass / Treble boost: 14dB Bass / Treble cut: 14dB Station memory: Preset 10 FM radio stations FM tune options: Auto and Manual with 25 kHz steps Key components of this audio system are ATmega32A - 8bit microcontroller, TT502 ( TEA5767 ) stereo FM radio module, PT2314 audio processor and μPC2002 audio power amplifier. This system is design to work with 12V - 15V (2A) DC power source and KA7632 multi-output regulator is used to manage power requirements to the above mentioned components. Prototype version of digital audio amplifier User interfa...

Smart Audio Box (SAB) is microprocessor controlled audio switch and amplifier system, which is specifically design for audio composers and for audio engineers. SAB consist of 4 high impedance stereo inputs and two output modes. One output mode can drive stereo headphone/earphone and other output mode can drive pair of 8W speakers. In prototyping stages we identify those modes as " Personal Mode " (headphone output) and " Audience Mode " (power amplifier output). Another main feature of this system is its programmable 16 step attenuation controller. This attenuation controller helps to control the audio output level of each output-mode. Prototyping version of Smart Audio Box The main component of SAB system is ATmega8 MCU, other than that headphone amplifier is design around NJM4556 high current operational amplifier and power amplifier is based on TDA1521A. To operate, this system requires 2 power sources. Microcontroller, ADC interfaces and CMOS logic-s...

This post show completed view of digitally controlled audio power amplifier with virtual surround (which we described in previous post). All the speaker enclosures, power amplifier casing and electronic system are design and developed by us. Configuration of this given step is as follows: System Components: Power Amplifier, 2 main speaker units, 1 sub-woofer and 18V (5A) SMPS. Speaker System: Main speaker system consist with 8Ω (45W) 6½ inch Woofer, 8Ω (50W) 3 inch Tweeter with passive crossover. Subwoofer System: 3Ω (200W) 8 inch Bass Woofer. All the speaker enclosures are mad out of 9mm MDF (medium density fiberboards) and power amplifier casing is made using 2mm acrylic sheets. More views of this audio system are available in here .

In this post we describe digitally controlled 2.1 channel audio power amplifier with virtual surround sound. This audio amplifier is based around Microchip’s PIC18F452 microcontroller and ST microelectronics TDA2050 power amplifiers. Key system specifications and features of this audio system are listed in below: Supply voltage and PSU: D.C - 16V to 19.5V with 3A PSU. (Recommended: 18.8V, 3A PSU) Input(s): 2 analog input lines. (for Left and Right channels) Functions: Volume, Bass, Treble, Loudness, Mega Bass, Surround Effects Volume control: 0dB to 75dB Attenuation per channel with 1.25dB step Mute: 100dB Attenuation per channel Calculated channel separation (Approximately): 85dB - 88dB Bass control: ±14dB with 2dB step Mega bass control: 0dB to 30dB with 7 control steps Treble control: ±14dB with 2dB step Surround Sound: Based on AViSS 3D surround algorithm with 4 operational modes (Disable, Low, Normal and Wide) Output channels: 3 (2 channels + 1 subwoofer driver channel) Output po...

TDA2030 is most popular, high quality - low cost audio power amplifier and successive version of TDA2006. Typically TDA2030 deliver 14W in 24V with 4&#8486 output load and 8W in 8&#8486 output load. Because of it’s wider power bandwidth (10Hz to 140 kHz) and extremely small amount of distortion (0.1% - 0.5%), TDA2030 deliver excellent sound quality with higher performance. In this project we design basic version of TDA2030 mono power amplifier for general use and its design to work with 9V – 24V (500mA) Power Supply Unit. When building the circuit it is recommended to use PCB design and its important to attach suitable heat-sink to the TDA2030. In this design it is not necessary to have electrical isolation between the IC and the heat-sink. To get the complete circuit diagrams and PCB designs (Eagle) please check the google drive .