Types Of AmpliFiers

Amplifiers are one of the most essential components in a variety of audio processing situations, which makes them of special significance when we discuss their use in radio broadcasting.

1. Power amplifiers
 
Power amplifiers are used whenever we need to raise the strength of the signal high enough to drive a speaker: The larger the speaker, the larger the output required of the power amplifier…and consequently the greater the gain required of the power amplifier. Power amplifiers are often used in live sound situations - concerts, for instance - because the speakers required for the sound to reach a large gathering are very large.
Power amplifiers may or may not have controls of their own, though they commonly have a knob that allows you to control the gain (output). They also usually have connectors for a pair of speakers, and may accept a variety of connector types depending on the specific use they are meant for.


In the radio studio, the power amplifier is usually used to feed the studio monitor speakers. Most often, it is controlled from the mixing desk itself, with the faders of the mixer used to adjust the input (and thereby the output) of the amplifier.

Boss KIT-2 Complete 8 Gauge Amplifier Installation Kit

2. Distribution amplifiers
 
The distribution amplifier (DA) is a type of amplifier used to keep the strength of the signal constant across a large number of outputs when a single source must feed multiple devices. Just as the pressure of water in a water pipe decreases if it is connected to too many taps, the strength of a signal in the system will fall if the same signal must be given to multiple outputs.


In the radio studio, there are usually a number of different pieces of equipment - and they may all need to be fed the output from a single mixer. (The same mixer may also give an output for the production studio, if the mixer in question is in the broadcast studio - and indeed, even to the voice booth or recording floor.) This means the signal will be greatly diminished if we just split it up electronically and try to feed it to all these devices. This is where the distribution amplifier comes in: The mixer output is fed to the DA, which boosts the strength of the input signal, and feeds it to a number of outputs and thereby solving our problem of lowered signal strength.

In the radio studio, DAs typically have stereo inputs and a number of stereo outputs - often 8 outputs or more - which can then be connected to stereo recording devices and the transmission system. A low cost option would be to keep the entire system mono, and have a DA that has mono inputs and outputs; but these are comparatively rare as an option, since there is very little difference in price for such a setup.

3. Headphone amplifiers

 
A headphone amplifier is a specialized type of distribution amplifier that is used to connect more than one headphone to the same output. When a programme is being made, or a transmission is taking place, more than one person will often need to listen to the audio output at the same time. Connecting multiple headphones to the same headphone socket would lead to the same situation we saw above: A weak signal that cannot be heard properly over any of the headphones. A headphone amplifier solves this by keeping the output to each pair of headphones constant.

AudioSource AMP-100 2-Channel Bridgeable Stereo Power Amplifier

Headphone amplifiers are often used in on air studios and on recording floors where each of the guests/speakers may be required to have a pair of headphones.

For more on headphones, see Section B: Loudspeakers & Studio Monitors on Page 190

4. Pre-amplifiers
 
Pre-amplifiers are used to boost the tiny output signals that emerge from many audio devices: Microphones, for instance, have outputs that are hardly a few microvolts strong. Pre-amplifiers boost these outputs to a level where they can be fed to other audio devices.
Pyramid PB717X 1,000-Watt 2-Channel Bridgeable Amplifier

For more on microphones, see Section B: Microphones on Page 198

In many field recorders and mixers, the pre-amplifier is built into the input into which the microphone's output will be connected. It is important for the pre-amplifier to be of good quality, since it boosts the microphone's signal by a large amount (meaning it will also magnify any distortions by a large factor); and because it is the first electronic signal processing unit in the chain (and is therefore responsible for the quality of the signal that will be fed to all parts of the chain of electronics that follows it). A good microphone connected to a bad pre-amplifier can ruin any advantage and quality gained by the quality of the microphone.

It must be noted that among pre-amplifiers, the ones used for LP players (phonographs or turntables) are a specific subtype that cannot be connected to any other variety of equipment.

                            

ANALOG & DIGITAL AUDIO

Sound travels as a series of waves - that is, as a continuous rise and fall in the pressure of the air at a given point in space. When we speak, our vocal chords vibrate at various frequencies, creating corresponding vibrations in the air around them. These vibrations - waves - are then transmitted by the particles that make up air, and the vibrations are passed along till they reach someone else's ears…or a microphone that is designed to pick up these vibrations.

For more on microphones, see Section B: Microphones on Page 198

Analog Audio
 
The microphone, in turn, converts these vibrations into an electrical signal, that rises and falls in exact correspondence with the rises and falls in the sound wave that is reaching the microphone. If the signal is then recorded on magnetic tape, what we have thus far is a process where a continuous wave or signal - even if it is changing from sound energy to electrical energy and stored as an arrangement of magnetic particles - is being preserved throughout the entire process. Since in each case, we have a signal that is analogous to the original sound wave that was produced, such signals are called analog signals.

Digital audio

Casio Men's MQ24-7B2 Analog Black Resin Strap Watch

As technology progressed, however, new ways to store information became available. One such technology was digital storage, where information of any kind - visual, audio, or a combination of both - could be stored as a series of numbers, which together represented the original information. The information was stored usually in combinations of ones and zeros, a system of mathematics called binary numbers. (In fact, the fact that the storage was in the form of numeral digits was why it began to be called digital storage in the first place!)

Digital signals and storage offer us vast advantages over the older analog system:


1. Digital signals can be stored more economically than analog signals can. An LP or long playing record could store about a half hour's worth of music per side. Today, a small digital music player the size of a matchbox can store ten times as much.

2. Digital signals can also be manipulated more easily than analog signals, both in terms of clearing out unwanted components, and in terms of making changes to the signals.

3. Digital signals can also be copied and duplicated more easily: There is no deterioration of the signal across copies, unlike what used to happen with analog storage methods. This also applies to transmission of the signal through cables or broadcast, where analog signals invariably pick up some noise, but digital signals do not by virtue of the way the information is carried in both cases.

Where audio was concerned, this presents a plethora of options, with high quality audio becoming easily accessible to everyone: The first item of digital audio to make it to the market was the compact disc or CD, which stores digital data on a spinning disc of plastic encased metal.

For more on compact discs, see Section B: Compact Discs on Page 138 and 
Section B: CD Writers on Page 145

Increasingly, audio recording - professional or for personal use, large radio station or community radio station - relies on digital audio equipment. Computers store information digitally, as do CDs, VCDs and DVDs. However, there is a downside to using digital technology; and that has to do with the way analog sound is converted to a digital signal by the digital sound equipment we use.

A/D conversion
 
We have already seen that a sound, when it originates, is a continuously rising and falling wave, and hence analog in nature. To convert analog sound into a digital signal, there has to be a process where we convert the characteristics of the sound wave into a set of equivalent numbers that describes the wave. This process is called Analog to Digital (or A/D) conversion, and the first step in this is called sampling.
Sampling is essentially the process of dividing the original wave up into a series of smaller slices. Obviously, it is easier to describe each slice more accurately than one can describe the wave as a whole. And if we then have

a description of the value of each slice (as an equivalent number), and a description of that number's position in the overall list of numbers describing the wave, it is fairly straightforward to reconstruct the original wave from these descriptions.

Analog: Inform Socks (3-Pack)-multi/l

The figure above shows the original wave, and slices we have made. We can reconstruct the wave by joining the samples (dots) that we have created. The reconstructed wave is not totally an accurate copy - it is more jagged than the original. This is the negative side of digital technology. A/D conversion is essentially a matter of approximation: The slices only give you an idea of what the original analog signal was like. However, this is becoming rapidly less of a drawback, as modern technology is using higher and higher sampling rates to make finer and finer slices of the original signal. If we can make the samples/slices much finer, the wave we can reconstruct from this information becomes closer and closer in shape to the original analog wave. It is generally accepted that if the sampling rate is twice the highest frequency wave in the audio signal, the results of sampling will be indistinguishable to the human ear from the original analog sound wave. This is why digital audio on CDs are sampled at 44100 Hertz (or 44100 samples per second, 44.1 KiloHertz or KHz) - because the highest frequency detectable by the human ear is 20000 Hz, and this is more than twice that. Digital video recordings record sound at 48000 Hz, so their audio is a little higher in quality. FM stations often sample the audio at 32 KHz, as the higher frequencies - 16000 Hz and above - often get lost in the broadcast process, and we need to be concerned with recording and reproducing audio only upto that limit.

Data/Bit Rate
 
The other factor that controls the quality and accuracy of the digital signal is the amount of information we can store about each of the samples/slices:

The more information we store about each sample, the greater the accuracy in reconstructing the original wave. In digital storage, each 1 or 0 that we use is called a bit of information. CDs usually use 16 bit sampling - that is, 16 bits to describe each sample. More recent pro audio equipment uses 24, 32, 48 or 96 bit sampling, leading to ever more accurate storage and retrieval.

D/A Conversion
 
Once the audio is stored in a digital format, we need equipment and techniques to convert it back into the original analog sound as well. The CD players, DVD players and MP3 music players that we see all around us today - including the music players built into many mobile phones - perform just this function: They convert the digital signal back into the analog signal, a process known as D/A conversion. This is the exact reverse of the sampling process.

As noted previously, both the sampling and the D/A conversion process involve some loss of audio information. Some people can be sensitive to this loss, and can 'feel' the difference between the digital version and the analog version of the same audio recording. But increasingly, as digital audio equipment improves, even low cost consumer grade equipment can give you a high enough grade of storage and reproduction to satisfy the vast majority of listeners.
                      

Measurement Amplifiers AS-4K (PART-2)

AS4K-ICP

4-Channel Amplifier for ICP^®Sensors

• Standard gain factors 1, 2, 5
• Integrated sensor power supply 4 mA
• Accuray 0.1%
• Linearity 0.02%
• Minimum input frequency appr. 2 Hz
• Cut-off frequency 20 kHz

Detailed information can be found in our PDF file

4-Channel Amplifier for ICP® Sensors

AS4K-LVDT

4-Channel Carrier Frequency Amplifier for Inductive Sensors (LVDT)

• 4 measuring ranges adjustable to sensor sensitivity
• Front panel settings for phase, zero, gain
• Integrated sensor power supply + 5 Vrms
• Accuray < 0,3% (typ. 0.1%)
• Linearity 0.02%
• Cut-off frequency 400 Hz, standard filter 1 kHz
• Synchronising of 5 kHz CF for all channels

Detailed information can be found in our PDF file

Handbook of Measurement and Control: an Authoritative Treatise on the theory and Application of the LVDT 

4-Channel Carrier Frequency Amplifier for Inductive Sensors (LVDT)

AS4K-FU

4-Channel Frequency/Voltage Converter (F-V Converter)

• Range 1 / 2 / 5 / 10 / 20 / 50 / 100 / 200 [kHz]
• Lower frequency limit of input signal 3.5 Hz
• Input 5 V / 12 V (digital)
• Integrated sensor power supply + 5 V DC (max. 50 mA), external feed + 12 V DC, + 24 V DC optional
• Accuracy 0.1%
• Linearity 0.02% - 0.05% (depending on range)
• Frequency limit of output signal 250 Hz - 3 kHz (depending on range and signal)
• Moving average filter 1, 16, 128 values
• Sensing of rotation
• Noise and residual ripple 2 mVeff

Detailed information can be found in our PDF file

 Simplified Design of Voltage/Frequency Converters (EDN Series for Design Engineers)

4-Channel Frequency/Voltage Converter (F-V Converter) 

AS4K-TQ

2 Channel Frequency Discriminator for Torque Sensors

• Range 10 ± 1.667; 10 ± 5 [kHz]
• Input 5 V / 12 V (digital)
• Integrated sensor power supply + 5 V DC (max. 50 mA), external feed + 12 V DC, + 24 V DC optional
• Accuracy 0.1%
• Linearity 0.02% - 0.05% (depending on range)
• Frequency limit of output signal fg = fin / 10 e.g. fin = 10 kHz, fg = 1 kHz
• Moving average filter 1, 16, 128 values
• Noise and residual ripple 2 mVeff

Detailed information can be found in our PDF file

 Mark-10 STE20 Wrench Extension Torque Sensor, 20 x 0.02 lb-in

2 Channel Frequency Discriminator for Torque Sensors

Measurement Amplifiers AS-4K (PART-1)

Analog Measurement Amplifiers   AS4K

Best suited for test bench applications:

• Data acquisition analog or via internal USB or external ADC cards
• Standard DAQ software (e.g. DASYLab, DIAdem, LabView)
• Connectors on backplane for various ADC cards and for routing of analog (± 10 V)and digital signals (I/O, clock, trigger, PWM, ...)
• Front panel with standard or customer-specific sensor connectors
• Top-grade technology
• Power supply for stationary, or DC/DC converter for mobile use

Choose more information with the following links:

• AS4K-DC     DC Amplifier
  Insulated DC Amplifier for Measurement of Voltage (100 mV...50 V) and Current Signals (Shunt Integrated, 4...20 mA or ± 20 mA), Potentiometers, Hall Sensors, Active Pressure Sensors, etc. Integrated Supply Voltage for Potentiometers.
• AS4K-Strain-Gauge     Strain Gauge Amplifier
  Insulated measurement of strain gauge bridges with resistance ranges from 350 to 1,000 ohms. Integrated power supply, 4- and 6-wire connection.
• AS4K-TC     Signal Conditioning for Thermocouples
  Insulated measurement of thermocouples. Integrated cold spot compensation and precise linearisation, monitoring cable break.
• AS4K-Pt100     Temperature Amplifier for Pt100
  Insulated temperature measurement with PT100 sensors.
• AS4K-ICP     Measurement with ICP®-Sensoren
  Conditioning measurement signals from ICP® sensors. Integrated power supply.
• AS4K-LVDT     Carrier Frequency Amplifier for LVDT Sensors
  Carrier frequency amplifier (5 kHz) for inductive sensors like LVDT.
• AS4K-FU     Digital Amplifier with DSP for Frequency Sensors
  Insulated measurement of frequency and incremental sensors.
• AS4K-TQ     Digital Amplifier with DSP for Torque Sensors
  Insulated measurement at torque sensors with frequency output.

Features fpr all modules:

• Plug-in filters for interference suppression, anti-aliasing, frequency limiter, etc., low- and high-pass 4th order (Butterworth or Bessel characteristic)
• Very low-noise, residual ripple: < 1 mV RMS resp. 2 mV RMS
• Accuracy 0.1% resp. 0.2%
• Electrical insulation 1,000 V DC
• High channel density (4 channels with standard width 8 unit)

Detailed information can be found in our PDF file

Analog Amplifiers for Voltage,- Current- and Sensor Signals

AS4K-DC

4-Channel Universal Analog Signal Amplifier for Voltage and Current

• Current Range : 4...20, ± 20 [mA]
• Voltage Range : 0.1/ 0.2/ 0.5/ 1/ 2/ 5/ 10/ 20/ 50 [V]
• Integrated sensor power supply + 5 V
• Accuray 0.2% (typ. 0.1%)
• Linearity 0.02%
• Frequency limit max. 50 kHz, standard filter 5 kHz
• Noise and residual ripple
  Gain 0.2 - 20: 0.4 mVeff,
  Gain > 20: 0.4 mVeff + 3 µVeff x Gain

Detailed information can be found in our PDF file

Polk Audio PSW10 10-Inch Monitor Series Powered Subwoofer (Single, Black)

4-Channel Universal Analog Signal Amplifier for Voltage and Current

AS4K Strain Gauge Amplifier

4 Channel Analog Amplifier for Strain Gauge Sensors

• Range 1 / 2 / 4 / 10 / 20 [mV/V]
• Integrated sensor power supply + 5V
• 4- and 6-wire connection with automatic matching
• Accuracy 0.1%
• Linearity 0.02%
• Frequency limit max. 10 kHz, standard filter 5 kHz
• Noise and residual ripple 1 µVeff x Gain + 0.4 mVeff

Detailed information can be found in our PDF file
MXL MICMATEC XLR To USB Preamp for Condenser Microphones

Analog Amplifier for Strain Gauge Sensors 

AS4K-TC

4-Channel Thermocouple Amplifier

• Range 100 / 200 / 500 / 1000 [°C]
• Thermocouple type J, K (others on request)
• Integrated cold spot compensation and precise linearisation
• Monitors cable break
• Accuray 0.2%
• Linearity 0.02%
• Frequency limit max. 1 kHz, standard filter 10 Hz
• Noise and residual ripple 0.2 mVeff

AS4K-Pt100

4-Channel Analog Amplifier for Pt100 Sensors

• Range -100 ... + 100, +200, +500, +850 [° C]
• Linearisation and sensor feed 1 mA integrated
• 4-wire technology
• Accuracy 0.1 %
• Linearity 0.1 %
• Frequency limit max. 10 kHz, standard filter 10 Hz
• Noise and residual ripple 0.2 mVeff

Detailed information can be found in our PDF file


New STMICROELECTRONICS Evaluation Board For STM32F107VCT Both Type A & B Smartcard Support 

4-Channel Amplifier for Temperature

AS4K-TC

4-Channel Thermocouple Amplifier

• Range 100 / 200 / 500 / 1000 [°C]
• Thermocouple type J, K (others on request)
• Integrated cold spot compensation and precise linearisation
• Monitors cable break
• Accuray 0.2%
• Linearity 0.02%
• Frequency limit max. 1 kHz, standard filter 10 Hz
• Noise and residual ripple 0.2 mVeff

AS4K-Pt100

4-Channel Analog Amplifier for Pt100 Sensors

• Range -100 ... + 100, +200, +500, +850 [° C]
• Linearisation and sensor feed 1 mA integrated
• 4-wire technology
• Accuracy 0.1 %
• Linearity 0.1 %
• Frequency limit max. 10 kHz, standard filter 10 Hz
• Noise and residual ripple 0.2 mVeff

Detailed information can be found in our PDF file
 
4-Channel Amplifier for Temperature

Insulated Signal Conditioning Amplifiers (PART-2)

ISO-DC Module

Electrically Insulated Measurement of Voltage and Current with Shunt Sensor

• Measurement ranges: 150 mV, 500 mV, 1 V, 10 V (others on request)
• Cut-off frequency max. 10 kHz, standard filter 5 kHz (Butterworth)
• Second voltage output through additional plug-in filter

Detailed information can be found in our PDF file

Electrically Insulated Measurement of Voltage and Current  

ISO-ICP Module

Electrically Insulated Conditioning of ICP^® Sensors

• Minimum input frequency 2 Hz
• Integrated sensor current supply 4 mA
• Residual ripple typ. 2 mVpp
• Accuracy 0.1 %
• Gain 1, 2, 5
• Cut-off frequency max. 10 kHz, standard filter 5 kHz (Butterworth)
• Single and bipolar input / output: ± 10 V, 0-10 V, ± 20 mA, 0-20 mA, 4-20 mA
  (please specify one configuration with order)
• Second voltage output through additional plug-in filter

Detailed information can be found in our PDF file

Electrically Insulated Conditioning of ICP® Sensors

ISO-RMS Module

Electrically Insulated Signal Conditioning with RMS Signal Output

• 2 outputs: 1x AC, 1x DC (True-RMS)
• Residual ripple current typ. 2 mVpp
• Accuracy 0.1 %
• For all sensors like strain gauge, potentiometer, DC, shunt, as RMS signal generator,
• with ICP® sensors especially suited for monitoring of vibration

Detailed information can be found in our PDF file

Electrically Insulated Signal Conditioning with RMS Signal Output

ISO-IF Module

Electrically Insulated Forming of Rotational Pulse Signals

• Integrated sensor power supply 5 V DC
• Input frequency range 0 ... 50 kHz
• Input voltage range 50 mV ... 60 V
• 1, 2, or 3 channels
• Insulated output voltage 5 V DC, max. output current 150, 90, 40 mA

Detailed information can be found in our PDF file

Electrically Insulated Forming of Pulse Signals

ISO-Arithmetic Module

Electrically Insulated Signal Combination

• Adds two voltage signals
• Subtracts two voltage signals
• Multiplies two voltage signals
• Divides two voltage signals
• Multiplies two voltage signals and calculates average values

Detailed information can be found in our PDF file

Electrically Insulated Signal Arithmetic

Insulated Signal Conditioning Amplifiers (PART-1)

ISO Modules

Electrically Insulated Signal Conversion and Conditioning,
Temperature Measurement, and Signal Combination

• ISO-FIL Module     Signal Converter for Voltage and Current
  Electrically insulated low noise signal converter for voltage and current signals
• ISO-TC Module     Amplifiers for Thermocouples
  Electrically insulated acquisition of temperature values with thermocouples
• ISO-PT Module     Amplifiers for Pt100
  Electrically insulated acquisition of temperature values with Pt100
• ISO-Strain-Gauge     Amplifiers for Strain Gauge Bridges
  Conditioning measurement signals from strain gauge bridges with resistances ranging from 350 to 1,000 ohms. Integrated sensor power supply
• ISO-Poti Module     Amplifiers for Potentiometer
  Conditioning measurement signals of potentiometer sensors. Integrated power supply
• ISO-DC Module    Differential Insulated Measurement of DC Voltage
  Differential measuring of voltage and shunt sensor current
• ISO-ICP Module     Insulated Amplifier for ICP® Sensors
  Electrically insulated conditioning of ICP® sensors. Integrated current supply of 4 mA
• ISO-RMS Module     Amplifier for RMS Output
  Electrically insulated signal conditioning with RMS signal output
• ISO-IF Module     Insulated Pulse Forming
  Electrically insulated pulse forming of rotational signals from speed counters, Hall generators, incremental counters, etc.
• ISO-Math Module     Insulated Amplifier for Arithmetic Functions
  Electrical combination of two signal voltages, and arithmetic calculation of values

All modules have the following features:

• Flexible filtering characteristics through plug-in filters (suppression of interferences, anti-aliasing, frequency limitation)
• Comes with one low-pass filter (standard frequency)
• Standard frequencies (Butterworth or Bessel filter, 4th order): 10, 30, 50, ..., 3k, 5k, 10k [Hz]
• 5 kHz Butterworth, if not otherwise specified (other filters in 4th or 8th order on request)
• Extremely low-noise, typical residual ripple 2 mVpp
• Accuracy 0.1%
• 3-way insulation
• Electrical insulation 1,000 V DC
• Supply voltage 24 V DC (12 V on request)
• DIN-rail mounting                                                                                                                                                                                                                                                                                                  
  

  ISO-FIL Module

  Electrically Insulated Transmission and Filtering of Voltage and Current Signals

  • Single and bipolar input / output: ± 10 V, 0-10 V, ± 20 mA, 0-20 mA, 4-20 mA
    (please specify one configuration with order)
  • Cut-off frequency max. 10 kHz, standard filter 5 kHz (Butterworth)
  • Second voltage output through additional plug-in filter

  Detailed information can be found in our PDF file
  
  Electrically Insulated Transmission and Filtering of Voltage and Current Signals
                                                                                                                                                           

  ISO-Pt100 Module

  Floating input signal conditioning for Pt 100 sensors

  • Integrated precise linearisation and sensor current supply 1mA
  • 4-wire connection
  • Range - 100 ... + 500 °C (others on request)
  • Single and bipolar input / output: ± 10 V, 0-10 V, ± 20 mA, 0-20 mA, 4-20 mA
    (please specify one configuration with order)
  • Cut-off frequency standard 10 Hz (Butterworth), max. 5 kHz
  • Second voltage output through additional plug-in filter

  ISO-TC Module (Thermocouple)

  Floating input signal conditioning for thermocouples

  • Integrated precise linearisation and cold spot compensation
  • Monitoring of wire break
  • Thermocouple type J, K (others on request)
  • Range - 100 ... + 1,000 °C (others on request)
  • Single and bipolar input / output: ± 10 V, 0-10 V, ± 20 mA, 0-20 mA, 4-20 mA
    (please specify one configuration with order)
  • Cut-off frequency standard 10 Hz (Butterworth), max. 1 kHz
  • Second voltage output through additional plug-in filter

  Detailed information can be found in our PDF file
  
  
  Temperature Measurement with Pt100 and Thermocouples
  
  
  

  ISO-Strain-Gauge Module

  Conditioning Measurement Signals from Strain Gauge Bridges

  • Resistance values 350 - 1,000 ohms (optional 120 ohms)
  • Integrated sensor power supply + 5 V DC
  • 4-wire / 6-wire connection
  • Range 2, 4, 10 mV/V (other on request)
  • Full bridge (optional half bridge)
  • Single and bipolar input / output: ± 10 V, 0-10 V, ± 20 mA, 0-20 mA, 4-20 mA
    (please specify one configuration with order)
  • Cut-off frequency max. 10 kHz, standard filter 5 kHz (Butterworth)
  • Second voltage output through additional plug-in filter

  Detailed information can be found in our PDF file
  
  Conditioning Measurement Signals from Strain Gauge Bridges

  
   
  

  ISO-Potentiometer Module

  Conditioning Measurement Signals of Potentiometer Sensors

  • Integrated sensor power supply + 5 V DC
  • 3-wire / 5-wire connection
  • Gain: 1, 2, 4, 8
  • Single and bipolar input / output: ± 10 V, 0-10 V, ± 20 mA, 0-20 mA, 4-20 mA
    (please specify one configuration with order)
  • Cut-off frequency max. 10 kHz, standard filter 5 kHz (Butterworth)
  • Second voltage output through additional plug-in filter

  Detailed information can be found in our PDF file
  
  Conditioning Measurement Signals of Potentiometer Sensors

                          

Data Acquisition Software, Software Drivers and Functional Library

DAQSoft and Software Drivers

• DAQSoft     Data Acquisition Software DAQSoft
  Comfortable data acquisition software for measurement with DAQ Systems DASIM, SIQUAD and AD-ETH
• DaSoft     Parameter Setting Software DaSoft
  Comfortable software for parameter setting for the measurement systems DASIM and SIQUAD
• Software Drivers     Software Drivers for DASYLab, Lab-View and Diadem
  Software drivers for DASYLab, Lab-View and Diadem for measurement with the DAQ Systems DASIM, SIQUAD and AD-ETH
• Functional Library     Functional Library
  Functional library with all functions for setting and measurement with the DAQ systems DASIM, SIQUAD and AD-ETH

Sharp BD-HP21U Blu-ray Disc Player

Its low price and on-board high-resolution audio decoding make it tempting, but the Sharp BD-HP21U fails to deliver a consistently great picture.


The Sharp BD-HP21U packs lots of metal--literally. It's large and heavy, so much so that you could mistake it for an old Laserdisc player. This model carries a moderate price ($280 as of 12/12/08), but that gets you only a Blu-ray player with hit-and-miss image quality.

When you grab a disc off the shelf to play on the BD-HP21U, grab a book, as well: It takes an agonizing 2.5 minutes to load a typical Blu-ray disc--more than twice as long as any other player we've ever tested. On the other hand, once you have the disc playing, the player responds to the remote control as well as any.

And what do you see during playback? Our PC World Test Center judges found extremes of good and bad in viewing our suite of test discs. On our tests of both The Phantom of the Opera and The Searchers in Blu-ray, I noted that the Sharp wasn't, well, sharp. The Phantom DVD didn't look too good, either--another judge noted that its images appeared dull and flat. She also found the faces too red in The Searchers.

On the other hand, the player did very well on our Mission: Impossible III and Good Night and Good Luck tests. The latter showed notably good contrast, according to one judge.

Though I found this player easy to use, it does have some drawbacks that caught my attention. The small, programmable remote control fit comfortably in my hand, and the important buttons were all easy to get to (one of the advantages of a small remote). Unfortunately, though, the remote lacks a backlight.

The on-screen setup menu is logically designed and displays useful explanations of the options. But the icons look low-resolution and kind of amateurish. The 48-page manual is reasonably well designed, but Sharp doesn't put a PDF version on its Web site as other companies do.


As you'd expect for its price, the BD-HP21U isn't heavy on extra features. The player supports Blu-ray Profile 1.1 (which all players at this point must support, at minimum), but not the fancier features contained in Profile 2.0 (specifically, BD-Live for accessing supplemental content via the Internet). Notably, it natively supports Dolby TrueHD and DTS-HD Master Audio, converting those high-end soundtracks to standard PCM for amplifiers that don't support them.

Unlike its first-generation player, the Sharp BD-HP20U, Sharp's second-generation model just doesn't impress. The Sharp BD-HP21U does the job without frills, and without oomph.

Amplifiers

An amplifier is a device that takes a signal and makes it louder. There are several different types of amplifiers and many different uses of them, and this website offers useful information about where to purchase and evaluate Amplifiers.

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1. Amplifiers - Basics

2. Window to the Past

3. Evolution of Amplifiers

4. Places to Go

5. How Amplifiers work

6. The Techniques

7. Control

8. Types of Amplifiers

9. Amplifier the Band

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1. Amplifiers - Basics

An amplifier can be considered to be any device that uses a small amount of energy to control a larger amount, although the term today usually refers to an electronic amplifier. The relationship of the input to the output of an amplifier — usually expressed as a function of the input frequency — is called the transfer function of the amplifier, and the magnitude of the transfer function is termed the gain. There are numerous types of electronic amplifiers depending upon the application.

2. Window to the Past

Today most sound systems use transistor amplifiers for economic reasons, but valve amplifiers remain popular for guitar amplification, for "high end" hi-fi systems and analog production and replay equipment in recording studios.

3. Evolution of Amplifiers

One of the first devices to amplify signals was the carbon microphone. By channeling a large electric current through the compressed carbon granules in the microphone, a small sound signal could produce a much larger electric signal. The carbon microphone was extremely important in early telecommunications until other types of amplifiers were available.

4. Places to Go

Amplifiers can be purchased at major consumer electronics retailers or at retailers specializing in audio.

5. How Amplifiers work

The most common type of amplifier is the electronic amplifier, commonly used in radio and television transmitters and receivers, high-fidelity ("hi-fi") stereo equipment, microcomputers and other electronic digital equipment, and guitar and other instrument amplifiers. Its critical components are active devices, such as vacuum tubes or transistors.

How much an amplifier increases the signal level is called the gain. This is usually measured in decibels (dB). Mathematically speaking, the gain is equal to the output level divided by the input level.

A typical integrated amp, such as the one found in a receiver, can only produce a limited amount of current. A speaker, or other load, that will draw too much current at the output voltage will cause the sound to distort risking damage to both the speaker and amplifier. You should never turn an audio system up above the point at which it begins to noticeably distort (this is commonly known as "clipping"). Separate "power amps", mentioned above, can produce much larger amounts of current and can drive very low impedance speakers.

6. The Techniques

A good audio amplifier will have a band ranging from around twenty hertz to more than twenty kilohertz (the range of normal human hearing). It must be responsive to at least the highest frequency that can be reproduced by a Average CD.

7. Control

The properties of amplifier circuits distort the signal. This distortion comes in several forms including harmonic distortion and intermodulation distortion.

Harmonic distortion is fairly easy to explain. Hook an amplifier up to a spectrum analyzer, a device which graphs frequency against amplitude. Then apply a pure tone on the input channel, typically a sinusoidal signal of 1 KHz is used. The biggest hump on your analyzer should be the signal at 1 KHz. You will sometimes see humps at even intervals along the graph at even multiples of that base signal. These are the harmonics. The total harmonic distortion (THD) is the sum of these components relative to the signal.

How much noise is introduced by the amplification process? This is an undesirable thing that is the inevitable result of the electronics devices and components. It is measured in either decibels or the peak output voltage produced by the amp when no signal is applied.

Efficiency

How much of the input power is usefully applied to the amplifier's output? Class A amplifiers are very inefficient, in the range of 10-20% with a max efficiency of 25%. Modern Class AB amps are commonly between 35-55% efficient with a theoretical maximum of 78.5%. Commercially available class D amplifiers have reported efficiencies as high as 97%. The efficiency of the amplifier limits the amount of total power output that is usefully available. Note that more efficient amps run much cooler, and often do not need any fans even in multi kW designs.

8. Types of Amplifiers

Electronic amplifiers

Musical Instrument amplifiers

Carbon microphone

Magnetic amplifier

Optical amplifiers

Miscellaneous amplifiers

9. Amplifier the Band

For those requesting information on Amplifier the musical band, please feel free to visit www.amplifiertheband.com

Ethernet DAQ Module ADETH

AD Converter for Data Acquisition via Ethernet Interface

• 16 or 32 synchronous channels with anti-aliasing filter for DC signals
• Total sample rate 128 or 256 kS/s
• Resolution 16 bit, accuracy <
• Ethernet data acquisition via TCP/IP Stack (IP Vers. 4)
• Imtron software DAQSoft
• Drivers for DASYLab, DIAdem, LabVIEW
• RS 232 for configuring TCP/IP parameters

Detailed information can be found in our PDF file


Ethernet DAQ Module ADETH

4-Channel Acquisition SIQUAD

Digital Signal Conditioning Space Saving in Top Quality

• Cost-effective data acquisition via Ethernet and CAN interface with or without integrated PC and display
• Modular 4-channel amplifiers, insulated inputs with up to 64 channels per housing or 19" rack
• Sample rates up to 20 kS/S per channel, resolution 24 bit, accuracy <
• CAN interface for synchronous data acquisition from CAN bus
• Sensor data base, prepared for automatic sensor recognition (TEDS)

Detailed information can be found in our PDF file


Digital Signal Conditioning SIQUAD

Universal DAQ System :- DASIM

Computer Controllable Intelligent Measuring System

• Outstanding functionality with one DSP per channel for a.o. zero balance, self-test, sensor control, digital filtering
• High flexibility through only two types of amplifiers (2 channels each with insulated inputs) for nearly all types of sensors:
  Universal Amplifier for strain gauge, DC voltage, DC current, tachometers, potentiometers, shunt sensors for current measurement, thermocouples, Pt100 sensors, frequency sensors (analog, digital), torque sensors, telemetry, incremental encoders, ICP® sensors. Carrier Frequency Amplifier for strain gauges (full- half-, and quarter-bridge), inductive torque measuring hubs, and LVDT sensors.
• Outputs analog U1 = ± 10 V, U2 = (0...± 2) x U1, plus digital via Ethernet
• Communication e.g. with a SPC via Field Bus like ProfiBus or Interbus
• Link to decentral signal conditioning modules DSK via RS 485 Field Bus Interface
• CAN interface e.g. in automotive applications for communication with CAN Bus
• CAN Interface Module for acquiring data from CAN bus
• Excellent interference immunity in aggressive industrial environments by extensive EMC measures
• Housings and racks with mains power supply for stationary or extended-range power supply (5 - 36 V DC) for mobile use
• Extension DASIM-IPC with integrated PC and/or display
• Easy-to-use Imtron PC software: DaSoft for parameter setting (via RS 232 and/or Ethernet), and DAQSoft for data acquisition and analysis (via Ethernet). Drivers for standard DAC software like DASYLab, DIAdem, and LabVIEW are optionally available.

Detailed information can be found in our PDF file

Measurement System DASIM

Make a COM1 to COM2 crossover cable

This method describes how to make a COM1 to COM2 crossover cable, without using a soldering iron.
 
This means that you can transmit into COM1 using a standard terminal program, and receive these same bytes into COM2.

Note: this method is only recommended to link two serial ports on the same machine, as the ground line is not attached. It also does not link the flow control lines.






Figure 1: How to make a crossover cable

What you need

• Two RS232 extension cables
• 2 gender changers
• 2 bits of wire. I used standard 0.1 inch headers, as used in the millions in the electronics industry.

All these bits are available at any computer store. I purchased all these pieces from Dick Smith Electronics.

What you do

Poke the header into pins 2 and 3 of the gender bender, as shown in figure 2 below. 


 
Figure 2: Insert the bits of wire
As shown in figure 3 below, the transmit pin 3, and the receive pin is pin 2.
Warning: Depending on which piece of equipment you're talking about, the transmit pin and receive pin changes. The PC's transmit pin transmits into the devices receive pin, and vice versa.
 


 
Figure 3: Where to insert the bits of wire
Make sure pin 2 is going to pin 3 (ie: transmit connected to receive), and pin 3 is going to pin 2 (ie: receive connected to transmit). The completed article is shown in figure 4 below. Put a slight bend on the pieces of wire to make sure that there is good electrical contact.



Figure 4: The finished article

How to test

Download Terminal from http://bray.velenje.cx/avr/terminal. You can also download Terminal from this site. I recommend downloading it from Bray's site, as he will have the most up to date version. 

As you can see, typing in COM1 is received in COM2, and vice-versa.



Figure 4: How to test the crossover cable

Other things to note

In a normal crossover cable, all the flow control lines are connected. Also, to be fair, the ground line should be connected. However, in this case it's not so bad because both COM ports are from the same computer. 

This is a quick way to verifying that both COM1 and COM2 are working. If you are serious about using a crossover cable, construct a proper one.

General Optimization Tips for the PIC16Fx micro controllers

• To save bank switching, move variables in different banks together.In initialization code, at startup of the program, look at the order of initialization - first all variables in bank0, then in bank1 then in bank2, then in bank3.
  In initialization - may be some variables do not need initialization. Where is possible, reorder operators to let the compiler avoid redundant loads of W register or temp locations.Use variables in same bank in arithmetic expressions to avoid bank switching.If possible, take the chance to use byte arithmetic instead of word arithmetic.If possible, use of pointers to array's elements instead of index. Note that in small loops manipulating pointers, however, the overhead of the loop cancels out the saving using pointers, so its about equivalent.
  A series of:
  
  if
  else if
  else if ... often generates smaller code than the equivalent case statement.
  In switch - case, change constants to be sequental numbers, without gaps.
  Depending on the bank switching required:
  
  var = value1;
  if (!flag)
  var = value2;
  
  generates more optimal code then:
  
  if (flag)
  var = value1;
  else
  var = value2;
  
  Just make sure that var won't be used in a interrupt while this code executes.Clearing, incrementing, and decrementing a byte are single instruction operations. Assigning a value to a byte requires 2 instructions (value -> W, and W -> byte).Use bits instead of unsigned chars whenever possible. Bit sets, clears, and tests and skips are all single instructions. Since you can't declare bits in a function, you may benefit from a globally declared bit.There is overhead to making function calls. Try replacing some of your smaller functions with macros.Large blocks of duplicated code should be replaced with a function and function calls if stack space allows.
• Optimization of existing logic. I have yet to be given a project with non-changing requirements, so I try to write my code to be very flexible. As it gets closer to the end of the project, I find some of the flexibility isn't needed, and may be removed at a code savings.
  Thanks to Ivan Cenov [imc@okto7.com] and Michael Dipperstein [mdippers@harris.com].

Optimization Tip 1: Signed vs. Unsigned variables

Compare the assembly for signed and unsigned variables, and you will find that there is a few more instructions for doing comparisons on signed variables.

Conclusion 1:

Use unsigned integers and/or chars if possible.

Optimization Tip 2: Byte Loops

Ok, heres two pieces of code, that do exactly the same thing. Yet, one of them is finished 25% faster, with less memory space! Can you pick which one? unsigned char i;
for(i=0;i<250;i++) do_func(); //executes do_func() 250 times, in 3.25ms

for(i=250;i!=0;i--) do_func(); //executes do_func() 250 times, in 2.5ms
To figure this out, have a look at the assembly produced.

for(i=0;i<250;i++) do_func(); //executes 250 times in 3251 cy 1617 01B8 clrf 0x38 1618 260F call 0x60F 1619 0AB8 incf 0x38 161A 3008 movlw 0xFA 161B 0238 subwf 0x38,W 161C 1C03 btfss 0x3,0x0 161D 2E18 goto 0x618

for(i=250;i!=0;i--) do_func(); //executes 250 times in 2502 cy 1621 3008 movlw 0xFA 1622 00B8 movwf 0x38 1623 260F call 0x60F 1624 0BB8 decfsz 0x38 1625 2E23 goto 0x623

Conclusion 2:

Have your loops decrementing to zero, if possible. Its fast to check a ram variable against zero.

However, note that in the incrementing loop, do_func(); was called one clock cycle earlier. If you want speed of entry, choose the incrementing loop.

Optimization Tip 3: Integer Timeout Loops

If you want to poll a port, or execute a function a certain number of times before timing out, you need a timeout loop.

unsigned int timeout;
#define hibyte(x) ((unsigned char)(x>>8))
#define lobyte(x) ((unsigned char)(x&0xff))
//the optimizer takes care of using the hi/lo correct byte of integer

• Loops to avoid with timeouts: 320000 to 380000 cycles for 20000 iterations.
  
  for(timeout=0;timeout<20000;timeout++) do_func(); //380011 cycles
  for(timeout=20000;timeout!=0;timeout--) do_func(); //320011 cycles |
  
  
• Best loop for a timeout: 295000 cycles for 20000 iterations.
  
  //we want to execute do_func() approx. 20000 times before timing out
  timeout=(20000/0x100)*0x100; //keeps lobyte(timeout)==0, which speeds up assignments
  for(;hibyte(timeout)!=0;timeout--) do_func(); //295704 cycles
  
  Notice the features of the loop shown above.
  
  1. It only tests the high byte of the integer each time around the loop.
  2. It checks this byte against zero, very fast.
  3. When initializing variable timeout, it takes advantage of the fact that the assembly command to initialize a ram variable to zero is one instruction, whereas to assign it a number its two instructions.
  

Conclusion 3:

• Have your loops decrementing to zero, if possible, its easy to check a ram variable against zero.Only test the high byte of an integer in a timeout loop, its faster.
• When assigning integers, its faster to assign zero to a ram variable, rather than a number.

Optimization Tip 4: Timeout loops using built in timers


Of course, the fastest form of timeout is to use the built-in PIC timers, and check for an interrupt. This is typically 70% faster than using your own timeout loops.

//set up tmr0 to set flag T0IF high when it rolls over
while(RA0==0 && !T0IF); //wait until port goes high

Conclusion 4:
Use the built in timers and/or interrupt flags whenever possible.
Optimization Tip 5: Case statements

Slow and Inefficient c=getch(); switch(c) {   case 'A':   {     do something;     break;   }  case 'H':   {     do something;     break;   }   case 'Z':   {     do something;     break;   } }

Fast and Efficient c=getch(); switch(c) {   case 0:   {     do something;     break;   }  case 1:   {     do something;     break;   }   case 2:   {     do something;     break;   } }

The Hi-Tech C optimizer turns the switch statement into a computed goto if possible.Conclusion 5:

• Use sequential numbers in case statements whenever possible.

Optimization Tip 6: Division in Hi-Tech C

If you use Hi-Tech C, and there is any mathematical division at all in the entire program, this uses up between 13 and 23 bytes in bank0, and some EPROM/flash.
This occurs even if the variables used are not in bank0.

Occurrence	RAM usageROM/flash usage	Fix/Explanation
Any mathematical division at all in the entire program using a variable of type 'long', even if all variables do not reside in bank0.	23 bytes in bank0large, it has to include ldiv routines	Use combinations of bit shifts ie: x=x*6 is replaced by x1=x;x2=x;x=x1<<2 + x2<<1
Any mathematical division at all in the entire program using a variable of type 'unsigned int', even if all variables do not reside in bank0.	13 bytes in bank0large,it has to include ldiv routines	Use combinations of bit shifts
Any mathematical division involving a divisor that is a power of 2, ie: x=x/64;	-low	Use combinations of bit shifts
Any mathematical division involving a divisor that is not a power of 2, ie: x=x/65;	-high	make your divisors a power of 2, ie: 2^5=32.

Conclusion 6:

If necessary, make it easy on the C compiler and use bit shifts, and divisors that are a power of 2. Divisors that are a power of 2, such as 256=2^8, can be optimized into a bit shift by the C compiler.

If you dont use any division at all in the program, you will save 23 bytes in bank0 and a portion of ROM ldiv() routines.