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Amplifier Circuits:
Variable Gain , Page 4
Variable Gain Amplifiers: #'s - A
B - F
G - O P - Z
Amplifier -- Main Page
Last Updated on:
Tuesday, March 20, 2012 05:57 AM |
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Circuits Designed by Dave
Johnson, P.E. : |
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Variable Isolated AC Voltage Spans 0VAC To 280VAC - I designed and
built this circuit about 25 years ago. It came in handy for many projects that
were powered from 120 VAC, 240 VAC and 277 VAC. It provides complete isolation
from the power line. It uses two 1:1 isolation transformers that are wired in
parallel for the140vac range and in series for the 280vac range. The selector
switch also diverts power to the appropriate output socket to avoid mishaps in
sending the wrong voltage to the load. My home-built unit also included an AC
volt and amp meter to monitor the output. However, this circuit only indicates
the AC power connections....
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Links to electronic circuits,
electronic schematics, designs for engineers, hobbyists, students & inventors:
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Replacing Output Clamping Op Amps with Input Clamping Amps -
AN-402 Analog Devices Application Notes (app note added 2/06) So
far most clamping amplifiers have relied upon an output clamping
architecture and are called output clamp amps (OCAs) . A new
architecture called an input clamp amp (ICA) offers superior
clamping accuracy and lower distortion. |
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Settling Time of Operational Amplifiers - AN-359 Analog
Devices Application Notes (app note added 2/06) |
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Simple fixture statically tests programmable gain amplifiers -
26-Jun-08 Issue of EDN Using a simple fixture having a common
ground point, you can statically test digital gain-programmable
amplifiers.... [Design Idea by Marián Štofka, Slovak University of
Technology, Bratislava, Slovakia] |
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Simple variable frequency oscillator - ….(Circuit design
added 03/08) |
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Simple Variable Voltage Source - The high current regulator
below uses an additional winding or a separate transformer to supply
power for the LM317 regulator so that the pass transistors can operate
closer to saturation and improve efficiency. For good efficiency the
voltage at the collectors of the two parallel 2N3055 pass transistors
should be close to the output voltage..... (added 4/05) |
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Single IC provides gains of 10 and –11 - 7-Aug-03 Issue of EDN
Real-world data-acquisition systems require amplifying weak signals to match the
full-scale input range of an A/D converter. Unfortunately, when you configure them as
gain blocks, most common amplifiers have both gain errors and offset drift. The
typical two-resistor gain-setting arrangement found in many op-amp circuits has
serious accuracy and drift limitations.... [Design Idea by Moshe Gerstenhaber and
Charles Kitchin, Analog Devices, Wilmington, MA] |
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SPICE-Compatible Op Amp Macro-Models - AN-138 Analog Devices Application
Notes (app note added 2/06) |
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The Alexander Current-Feedback Audio Power Amplifier - AN-211 Analog Devices
Application Notes (app note added 2/06) |
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User's Guide to Applying & Measuring Operational Amplifier Specifications -
AN-356 Analog Devices Application Notes (app note added 2/06) |
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User's Guide to I.C. Instrumentation Amplifiers - AN-244 Analog Devices
Application Notes (app note added 2/06) |
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Using the AD813X Differential Amplifier - AN-584 Analog Devices Application
Notes (app note added 2/06) The AD813x differs from conventional op amps by the
external presence of an additional input and output. The additional input, VOGM,
controls the output common mode voltage. |
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Variable Gain Control Produces Pure Sine Wave - 10/27/94 EDN-Design Ideas
The circuit in Fig 1 delivers a pure, buffered, and level-controlled sine wave. With
no tuning requirements, the circuit works with all crystals up to about 30 MHz…..
[Design Idea by Barry Harvey, Elantec Corp, Milpitas, CA] |
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Variable gain stage uses voltage output DAC - 01-Aug-97 Issue of EDN A
voltage-output DAC normally generates an output voltage that is a fraction of the
input-reference voltage. In many designs, however, it is necessary to multiply the
input voltage by a programmable gain, or, in other words, to create a variable-gain
stage. You can easily implement a variable-gain stage using a low-cost voltage-output
DAC.... [Design Idea by Eugene Palatnik, BCI International, Waukesha, WI] |
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Variable Isolated AC Voltage Spans 0VAC To 280VAC - I designed and built
this circuit about 25 years ago. It came in handy for many projects that were powered
from 120 VAC, 240 VAC and 277 VAC. It provides complete isolation from the power line.
It uses two 1:1 isolation transformers that are wired in parallel for the140vac range
and in series for the 280vac range. The selector switch also diverts power to the
appropriate output socket to avoid mishaps in sending the wrong voltage to the load.
My home-built unit also included an AC volt and amp meter to monitor the output.
However, this circuit only indicates the AC power connections. …. [Designed by David
A. Johnson] |
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Variable Voltage Regulator (Ron J) - As Ron suggests, controlling the output
voltage from a regulator can be made variable in three ways....(electronic design
added 6/07) |
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Variable-gain stage uses voltage-output DAC - 01-Aug-97 Issue of EDN
A voltage-output DAC normally generates an output voltage that is a fraction of the
input-reference voltage. In many designs, however, it is necessary to multiply the
input voltage by a programmable gain, or, in other words, to create a variable-gain
stage. You can easily.... [Design Idea by Eugene Palatnik, BCI International,
Waukesha, WI] |
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Versatile Programmable Amplifiers using Digital Potentiometers with Nonvolatile Memory
- AN-579 Analog Devices Application Notes (app note added 2/06)
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Video VCAs & Keyers using the AD834 & AD811 - AN-216 Analog Devices
Application Notes (app note added 2/06) |
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Ways to Optimize the Performance of a Difference Amplifier - AN-589 Analog
Devices Application Notes (app note added 2/06)This Application Note presents
several ways to build and optimize the performance of a discrete difference amplifier.
It also recommends amplifiers that will make the overall solution cost/performance
competitive with monolithic instrument amplifiers. |
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Variable Gain
Amplifiers: #'s - A
B - F
G - O P - Z |
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