Tag Archives: Amplifier

LM386 SMD Audio Amplifier Module


The Tiny Audio Amplifier MODULE is a good choice for battery operation. It is based on LM386 IC, useful in various applications like robotics, science projects, intercom, FM radio and many more.


  • Power Supply 6V-9V
  • 300mW Output @ 8Ohms Load
  • On Board Potentiometer for Audio Level Adjust
  • Header Connecter for Supply, Signal in and Speaker
  • On Board Power LED
  • Input: Standard Audio Signal

LM386 SMD Audio Amplifier Module – [Link]

Tutorial on the Theory, Design and Characterization of a CMOS Transimpedance Amplifier

In this episode, Shahriar and Shayan discuss the design and characterization of a deceptively simple CMOS inverter-based transimpedance amplifier. The the large and small signal behavior of the CMOS inverter is discussed and measured using the Keithley 2450 and 2460 source meters. The transient response is also measured using a Keysight MSO-S series oscilloscope.

The small signal gain of the circuit is calculated from small signal parameters which are extracted directly by measuring the devices I/V characteristics. The NMOS/PMOS devices used are from an ADL1105 quad-discrete transistor IC. Through the use of a shunt-shunt feedback, the CMOS amplifiers is converted to a transimpedance amplifier which is capable of amplifying the current from a photo-detector diode by a gain of 30kV/A. The feedback theory is used to calculate the gain of the amplifier. The slides for this tutorial can be downloaded from The Signal Path website.

Tutorial on the Theory, Design and Characterization of a CMOS Transimpedance Amplifier – [Link]

1.6W Mono Audio Amplifier


1.6W Mono Audio Amplifier Project is based on TDA7231, which is class AB power amplifier with a wide range of supply.

  • Power supply: 5 To 12 VDC
  • Output: 1.6 W, 4 Ω / 1 W, 8 Ω
  • Low crossover distortion, soft clipping
  • PR1 Preset for Volume Adjust
  • Terminal pins for connecting power supply, input and output
  • Power On/OFF Switch
  • Power-On LED indicator
  • Four mounting holes of 3.2 mm each
  • PCB dimensions 36 mm x 52 mm

1.6W Mono Audio Amplifier – [Link]

ARC Digital Amplifier


Enjoy high-end sound quality for all your music with this small and modern digital amplifier.

The ARC was made to bridge the gap between high-end sound quality and the world of digital music. Designed as the perfect receiver and amplifier, this ultra-compact unit provides high-resolution USB audio streaming capabilities, high quality aptX Bluetooth audio and astonishingly detailed sound. For a great listening experience and immersive sound, all you need is a set of speakers and the ARC. Done.

ARC Digital Amplifier – [Link]

Understanding silicon circuits: inside the ubiquitous 741 op amp


Ken Shirriff’s blog looks inside the famous 741 OPMAP and discuss how it’s made and how it’s working:

The 741 op amp is one of the most famous and popular ICs[1] with hundreds of millions sold since its invention in 1968 by famous IC designer Dave Fullagar. In this article, I look at the silicon die for the 741, discuss how it works, and explain how circuits are built from silicon.

Understanding silicon circuits: inside the ubiquitous 741 op amp – [Link]

Introduction to OPAMPs and Applications

Operational amplifiers (OPAMPs) are high performance differential amplifiers in integrated form that can be used in many different ways. A typical OPAMP has a non-inverting input, an inverting input, two dc power pins, one output pin and a few other fine-tuning pins. On the following image you can see a typical diagram of an operational amplifier.

The basic OPAMP operation is simple. If the voltage applied to the inverting input is greater than the voltage applied to the non-inverting input then the output saturates to the negative supply voltage. In addition, if the voltage applied to the non-inverting input is greater than the voltage applied to the inverting input, then the output saturates at positive supply voltage.

This operation mode is limited and doesn’t give us the full idea behind OPAMP operation. The trick to make an OPAMP more useful is to provide negative feedback from the output to the inverting input. In the image below we see an OPAMP with negative feedback working as an inverting amplifier.

In this configuration a part of the output voltage is fed back to the inverting input and thus the gain of the OPAMP can be controlled and output isn’t saturating. The gain of such an amplifier is controlled by the two resistors Rf and Rin. The minus means that the output is inverted relative to input.

By adding more components on the feedback loop, different OPAMP circuits can be made, such voltage regulator circuits, current to voltage converters, oscillators, filters etc.

Beside the negative feedback, a positive feedback can be used. This way the OPAMP is driven toward saturation and works in either +Vs or –Vs output range. Applications of positive feedback is on comparator circuits and oscillators. Continue reading Introduction to OPAMPs and Applications

Narrowband RF Power Amplifier (520MHz)

The RF power amplifier stage is usually the final active block of any electronic system that is transmitting RF power. Relatively low power RF signals are amplified to produce a more powerful signal in order to be transmitted over greater distance. RF output power can range from a few mW to MW, depend by application. RF amplifiers before were all made using vacuum tubes but modern RF amplifier nowadays uses solid state devices like MOSFET, TMOS-FET, Bipolar junction transistors, and IGBT to amplify RF signals.

This circuit features the Freescale AFT05MP075GNR1 RF power LDMOS transistor as its RF amplifier solid state device. With the use of some components and proper board layouting, Freescale was able to create a 70 watts RF power amplifier with a gain of 18.5dB. This circuit requires a 12.5Vdc power supply able to provide the maximum power this LDMOS transistor can give. In this circuit, AFT05MP075GNR1 was configured to amplify RF signal with a carrier frequency of 520MHz suitable for UHF band mobile radio applications.

The Freescale AFT05MP075GNR1 was designed for mobile two-way radio applications with frequencies ranging from 136 to 520 MHz. It can be configured as a narrowband or wideband RF power amplifier. The high gain, ruggedness and broadband performance of this device make it ideal for large-signal, common source amplifier applications in mobile radio equipment. It can operate exceptionally in a very wide temperature range, from -40 to +150 degree Celsius. Though this device handles wideband application, it can still give full power across the band.

Narrowband RF Power Amplifier (520MHz) – [Link]

KaraOkay Microphone Amplifier


Here is an all-analog, all-through-hole, cheap & cheerful preamplifier for that perennial problem of getting the microphone amplification just right, which is a challenge not only with the faithful reproduction of lead vocals during concerts and recordings, but also with campfire and karaoke-ish performances specially when the beer takes hold.

KaraOkay Microphone Amplifier – [Link]

6EM7 Single-Ended Triode (SET) Vertical Amplifier


by Matt Renaud:

What really drove me to build this 6EM7 amp was an idea about amplifier layout. Looking back at most of my tube designs, and most of those on the internet, revealed a very typical pattern. Amplifiers tended to be flat chassis with tubes and transformers above and electronics below. From a historical perspective this makes perfect sense. Metal chassis were built this way to facilitate packaging and assembly. When people started to make tube amplifiers again, they just removed the upper case and built in the same way.

6EM7 Single-Ended Triode (SET) Vertical Amplifier – [Link]

Tiny audio amp produces 1.9 W from 5 V


by elektormagazine.com:

The PAM8905 is a new audio amp chip from Diodes Incorporated measuring just 1.5 x 2.0 mm. The design operates in class D mode, achieving a total harmonic distortion of 1% (plus noise) and delivering a maximum of 1.9 W into 8 ohm using a power supply in the range between 2.8 V to 5.2 V. The PAM8905 features an integrated boost converter powering the output stage to achieve the rated output power and maintaining volume with falling battery voltage. The boost converter is a fully synchronous design, ensuring a low external component count and high efficiency.

Tiny audio amp produces 1.9 W from 5 V – [Link]