App note: 400MHz, 2500V/µs, 9mA single/dual operational amplifiers

400MHz, 2500V/µs, 9mA single/dual operational amplifiers (PDF!) application note from Linear Technology: FEATURES 400MHz Gain Bandwidth Product 2500V/μs Slew Rate –85dBc Distortion at 5MHz 9mA Supply Current Per Amplifier 6nV/√Hz Input Noise Voltage Unity-Gain Stable 1.5mV Maximum Input Offset Voltage 8μA Maximum Input Bias Current 800nA Maximum Input Offset Current 40mA Minimum Output Current, VOUT = ±3V […]

App note: Lateral mosfet design recommendations for audio amplifiers

Semelab’s application note on lateral mosfet design recommendations for audio amplifiers: Semelab’s range of lateral mosfets has been specifically designed for audio power amplifiers and there are a number of advantages that they exhibit over bipolar transistors in these applications. This application note is intended to highlight these differences and give design guidelines in using the mosfets for […]

Voice echo project

A voice echo module with build-in amplifier project by Rajkumar Sharma of Electronics Lab: A project has been designed around Holteks Ht8970 voice echo IC. Project can be used in various audio systems karaoke, toys, animatronics, show, display, exhibitions, and sound equipment’s. The HT8970 is an echo/surround effect processor. It is designed for various audio systems […]

App note: High speed amplifier techniques

An old but interesting app note (PDF!) from Linear on high speed amplifier techniques: Most monolithic amplifiers have been relatively slow devices. Wideband operation has been the province o discrete and hybrid technologies. Some fast monolithic amplifiers have been available, but the exotic and expensive processing required has inflated costs, precluding widespread acceptance. Additionally, many of […]

DIY LM1876 dual 20W audio power amplifier

An audio power amplifier based on LM1876 from Electro Labs: We are building another enjoyable weekend DIY project. This is an audio power amplifier based on LM1876 which can deliver up to 20W per channel into 4 or 8 ohm load and guarantees less than 0.1% THD + N (Total Harmonic Distortion + Noise). The amplifier is […]

Digitally controlled 2.1 channel analog audio power amplifier

Dilshan Jayakody  writes: 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 […]

Audio: Headphone “Anti thump” delayed output rev 1.1

Rupert Hirst writes: A long awaited refresh, to my previous “Anti Thump” headphone output delay circuit, designed back in 2011. The Idea behind the circuit is to introduce a small delay, during initial power up, to electrically isolate and protect equipment connected directly to an amplifier. Often, during power up, amplifiers can produce an audible […]

Hi-Fi audio power amplifier for experiments and general use

Dilshan Jayakody writes: This is high quality audio power amplifier which we constructed for our audio related experiments. This amplifier is based on NXP’s TDA1521A integrated circuit and it is capable to deliver 2 × 6W audio output power with 20V – 25V asymmetrical power source. The design of this power amplifier is heavily based […]

Design and construction of a 24 GHz low noise amplifier

Jeff of MightyOhm writes: Tony Long and I designed and built a 24 GHz low noise amplifier for our ECE192 undergraduate independent study project at UCSD. The amplifier was designed with an early version of Agilent ADS, PCBs were fabricated on Rogers 5880 (Duroid), and we hand built several prototypes on K-connector fixtures that Tony designed. Measured […]

Measuring microamps & milliamps at 3 MHz bandwidth

Paul over at Dorkbotpdx writes: Recently I needed to actually “see” a current waveform in the 100 uA to 5 mA range with at least a couple MHz bandwidth.  This extremely expensive probe would have been perfect, but instead I built something similar for about $30 using the amazing Analog Devices AD8428 amplifier.

Smart audio box

Dilshan Jayakody has written an article about his open hardware project known as Smart Audio Box (SAB): 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 […]

App note: Build precise S/H Amps for fast 12 Bit ADCs

An app note from Analog Devices: Build precise S/H Amps for fast 12 Bit ADCs (PDF!) S/h amplifier circuits will use one of several standard architectures: closed-loop or open-loop, and inverting or noninverting configurations. No matter what circuit type designers employ, they need to incorporate a high-speed amplifier to buffer the input signal and a […]

Excel-based transistor amplifier calculator

Paulo shared an Excel-based transistor amplifier calculator.  ‘Besides the basic gain and biasing calculations many others implement, this calculator can also estimate noise which is a bit more involved’: ..Because this is a circuit I use frequently, I decided to make an Excel spreadsheet to ease the calculations. The spreadsheet started as a simple resistor […]