Ultra-LD Mk.2 200W Power Amplifier Module -  This new amplifier module supersedes both the Plastic Power module described in the April 1996 issue and the Ultra-LD module presented in the March 2000 issue.  It produces high power at very low distortion.  In fact, as far as we are aware, it is the lowest distortion class-AB amplifier that has ever been published. __ SiliconChip

Ultra-Low Distortion Audio Power Amplifier -  This is an unusual circuit for an ultra-low distortion power amp.  According to my original notes the circuit is dated January 1977 so the circuit is not exactly modern but it is still sufficiently different to be interesting.  The circuit was designed and sold as a card by a purveyor of surplus components but, even using mostly manufacturer's rejected transistors, we managed to get about 0.02% total harmonic distortion at 30 watts with a ±25v power supply into 8 ohms.  : no bad figure even in these days of MOSFET and ICs.  In 1977 anything below 0.1% was considered excellent.  And this figure was pretty repeatable without doing much selection. __ Designed by Richard Torrens

UltraLow Noise, 2.4GHz Gain Bandwidth Large-Area Photodiode Amplifier -  The combination of the ultralow noise JFET gain stage and the LT1806 low noise amplifier achieves the ultralow input noise performance.  The circuit’s input voltage noise was measured at 0.95nV/rtHz. __ Linear Technology/Analog Devices App Note, Mar 22, 2010

Ultrapure 1kHz Sine Wave Generator -  A lamp provides amplitude stability while the very low noise amplifier creates a pure sine wave signal.  The R an C values set the oscillator frequency and the feedback resistor sets the lamp current and output amplitude. __ Linear Technology/Analog Devices App Note, Jun 21, 2011

Umble-A distortion stompbox, inspired by Dumble Amplifiers. Schematic & PCB/perfboard layouts. -  A distortion stompbox, inspired by Dumble amplifiers. __ Contact: holler @ runoffgroove.Com

Uno-The Boogie MkI -  One of the first amps to offer distortion at lower volumes was the Boogie MkI amplifier.  As told by Randall Smith, the designer of the Boogie amp, these amplifiers were born of a practical joke on a guitarist friend.  Mr.  Smith modified a Fender Princeton to have considerably more gain and power, but appear stock.  As the story goes, Carlos Santana play-tested the amp and was impressed.  Carlos was quoted as saying the amp "really boogied!" Thus, the name of the amp was born. __ Contact: holler @ runoffgroove.Com

Use Resistor Noise to Characterize a Low-Noise Amplifier -  06/23/11  EDN-Design Ideas Measure gain or noise with an AC voltmeter.  If you know or can estimate a low-noise amplifier’s gain or noise bandwidth, you can measure the other spec using only a handful of resistors and an ac voltmeter (Reference 1).  The method in this Design Idea uses the Johnson Equation, which describes the amount of noise a resistor generates (Reference 2).  To find the missing parameter, measure an amplifier’s output-noise voltage, first for a shorted input and then using a few resistors of different values.  You can download an Excel spreadsheet that can calculate gain or noise bandwidth here. Design by Joe Geller, Whitesboro, NY

Using All four Amplifiers of the LT1397 to Drive Large zCapacitive Loads -  Four paralleled amplifiers increase load capacitor current drive capability.  A small ballast resistor at each output increases isolates the effects of each amplifier's different output offset. __ Linear Technology/Analog Devices App Note, Jun 29th 2012

Using an old Computer Box to build a guitar Amplifier -  In the event of the new ATX computer boxes, the former boxes for PC will become and are becoming obsolete.  It is almost unimaginable how many unused computer boxes will be unused or trashed very shortly in history.  That's a lot of metal.  They will be and are already common articles in junk shops, flee markets and garage sales. __ Designed by Jon Tirone, AKA John Fisher

Power Amplifiers:  #'s - C        D - K        L - P         Q - S        T - Z