Category Archives: Guides

What are Digital Pressure Sensors?

Various industrial systems use pressurized air, water, and other fluids. They use sensors to regulate and maintain proper pressure at different points in their activities. Although many systems continue using analog pressure sensors, digital versions are fast replacing them. A few examples serve to illustrate why pressure sensors are important.

Industrial icemakers need water at minimum pressure between 20 and 40 psi at the inlet—this allows the water inlet valve to function properly—although the exact water pressure requirement is dependent on the particular make and model of the refrigerator.  Pressure sensors with media isolation (waterproofing) provide a quick method of determining whether the water pressure is adequate for making ice.

Corporate Average Fuel Economy (CAFE) regulations demand that by 2025, the average fuel economy should be 54.5 MPG fleet-wide. Although popular belief is, each car maker’s fleet should have a significant presence of electric and hybrid vehicles to meet CAFE requirements, manufacturers are working towards advanced diesel and gasoline engines that should be able to meet the standards by themselves. One model of such advanced engines is the Achates Power Opposed-Piston engine. It exhibits fuel economy gains of 30-50% with significant reduction of emission, and is more cost effective compared to other solutions. The Achates engine requires a fuel injection system capable of a 2000 bar injection pressure.

For cutting different types of very hard, heat-sensitive, or delicate materials, industrial machines often make use of a water-jet cutting system. This avoids heat damages to the workplace edges or surface. An ultra-high-pressure pump operating at 40,000-100,000 psi produces a high velocity, high-pressure stream of water at 30,000-90,000 psi. Special MEMS pressure sensors are necessary to achieve the desired accuracy, resolution, and repeatability in such high-pressure measurement systems.

All Sensors makes the DLVR Series of mini digital output pressure sensors based on their patented CoBeam2 TM Technology, providing overall long-term stability by reducing susceptibility to package stress. Compared to single die systems, the DVLR differential pressure sensor technology improves the position sensitivity.

The DC supply voltage option of 3.3 or 5 V eases the integration of the sensors into a wide range of measurement and process control systems. I2C or SPI interface options allow direct connection to serial communication channels. The sensor goes into very low-power modes between readings, thereby minimizing load to power supply for battery operated systems.

With a pressure range of 0.5 to 60 inH2O and a common mode pressure of 10 psig, the DLVR pressure sensors offer better than 0.5% accuracy over temperature. While the storage temperatures range from -40 to +125°C, the sensors can operate from -25 to +85°C, under non-condensing humidity limits between 0 and 95%. The sensors are available in ten types of device packages including E1NS, E1ND, E1NJ, E1BS, E1BD, E2NS, E2ND, E2NJ, E2BS, and E2BD.

The DLVR series of digital output sensors are compensated and calibrated by the manufacturer and provide a stable and accurate output over a wide range of temperature. Intended use for this series involves non-ionic and non-corrosive working fluids such as dry gases, air, and similar. Moisture or harsh media protection is also available in the form of an optional parylene protective coating.

Interfacing XBee Modules with the Raspberry Pi

You can use two XBee modules to exchange data between them, as they are modular, self-contained, and low-cost components using radio frequency to communicate. Most XBee modules transmit on the ling-range 900 MHz or on 2.4 GHz using their own network protocol.

The primary advantage of using XBee modules is their size—nearly as large as a postage stamp. Therefore, it becomes easy to use them as sensor nodes in small projects. They consume very low power, and incorporate a special sleep mode that reduces their power consumption considerably. This is of advantage when using them on battery or solar power.

XBee modules can read their data pins and transmit the collected data to another XBee module. Therefore, if you have a sensor node and a data-aggregator node, you can easily link them together with XBee modules. As there is no micro-controller on the XBee module, it has only a limited amount of processing power for controlling the module.

This limited processing power makes it suitable for several sensor nodes, but not for all. For instance, although the XBee module can read data from sensors, it cannot do so from sensors requiring algorithms to interpret or extrapolate meaningful data—the additional calculations this requires may need assistance from a microcontroller. Incidentally, configuring an XBee module with the Digi configuration tool, X-CTU, requires a computer running the Windows operating system. For other operating systems, use a virtual machine to run Windows.

The XBee line of wireless modules has a list of different types, and you must select the one most suitable for your project. Some modules support proprietary protocols from Digi, others support UART or SPI to 802.11 b/g/n (Wi-Fi), while others support the ZigBee, and 802.15.4 protocols.

Several popular XBee modules support the ZigBee protocol. Therefore, many projects use the ZigBee modules available in the market. ZigBee modules have several more choices based on application. For instance, there are ZigBee embedded surface mount modules, and others that support the ZigBee feature set, and 802.15.4 protocols. The most popular among these are modules supporting the ZigBee Pro feature set.

The advantage with ZigBee is it is an open standard based on the IEEE802 standard, useful for network communications. ZigBee supports the formation of mesh networks to configure and heal broken links automatically, and allows the use of intermediate probes to transmit data over long ranges.

You can use a ZigBee development module with on-board USB interface or use an FTDI cable to interface it. Usually, in a mesh topology, you will need to assign each node with their individual roles as coordinator, router, or end device. You will need at least one coordinator in the network, while the mesh will require several routers.

You can use the explorer dongle to plug in the ZigBee module, and use the USB connector on the dongle to plug the combination into one of the USB ports on the Raspberry Pi (RBPi). To communicate, you will need another pair of dongle and ZigBee module on the USB port of a computer or laptop. You will need to select the correct com port, and a common baud rate on a HyperTerminal to initiate communication between the modules.

What are Signal Generators?

While developing electronic systems, engineers test the device by stimulating it with different types of signals they expect it to encounter in the field. The piece of test equipment that engineers use for generating the various test signals is the signal generator. A signal generator may be used as a stand-alone development system or in combination with other test instruments.

Depending on the requirement, signal generators may come in various forms and types, with each of them providing different forms of signals. For instance, some output only RF signals, others audio signals, while some provide a train of pulses, and still others offer different shapes of wave-forms. Although different signal generators offer a variety of facilities and performance levels, they may be broadly classified as:

Function Generators

This type of signal generators typically generates simple repetitive waveforms such as sine, sawtooth, square, and triangular waveforms. Early models of signal generators used analog circuits to generate the waveforms, but later models depend on digital circuitry to produce them. Users can set the frequency for the waveforms from the front panel of the instrument. Function generators operating at high frequencies are more expensive.

Arbitrary Waveform Generators

These signal generators can produce arbitrary waveforms that the user specifies. They are one of the most complex function generators and therefore expensive. Users can demand almost any shape of waveform for the instrument to generate, sometimes even by specifying points on the waveform. Some manufacturers compromise on the bandwidth because of the techniques they use to generate the signals.

RF Signal Generators

As the name suggests, these signal generators output radio frequency signals. Earlier analog models used free running oscillators with frequency locked loop techniques for improved stability. Nowadays, manufacturers use frequency synthesizers for achieving the stability and accuracy. Some also use direct digital synthesis along with phase locked loops for generating the required RF output.

Vector Signal Generators

These are a special type of RF signal generators for generating complex modulation formats such as QAM, QPSK, and similar.

Audio Signal Generators

These produce signals within the human audio range, typically from 20 Hz to 20 kHz. Suitable for audio and frequency response measurements, some versions offer repetitive and non-repetitive linear and logarithmic sweeps across the entire output. Some audio signal generators can synchronize with an oscilloscope to enable a visual display of the frequency response of the device under test. Usually with very flat response and extremely low levels of harmonic distortion, audio signal generators help in the measurement of distortion from the device under test.

Pulse Generators

This type of signal generators output pulses with variable height, width, and rise/fall times. Users can program them to output a single pulse after a defined time delay. The user may program all aspects of the pulse—its height, width, DC level, and its rise and fall times.

The large variety of signal generators producing different types of waveforms allows engineers to use them in various applications. They are useful for testing RF equipment, logic boards, and in hosts of other areas. Of course, for achieving the proper objective, the engineer has to determine the type of signal generator necessary for a given job.

What are USB Controlled Synthesizers?

Almost all devices now use the popular Universal Serial Bus (USB) interface for connecting and transferring data to and from other devices. Even laboratory devices are now available with the USB as their main interface to computers. Now, users can control frequency synthesizers also through the USB interface. Although neither the performance nor the features they offer are anywhere near those that bench top instruments provide, USB controlled synthesizers have their advantages. USB controlled synthesizers, although providing basic functions only, are far cheaper, requiring only a computer and software to operate. They are easy to handle, being mostly plug-and-play, have a tiny footprint, and yet, some of them operate beyond 25 GHz, with ultra-low phase noise. Here is a review of some of the popular synthesizers.

Pasternak Synthesizers

The synthesizer family, PE11S390X from Pasternak Enterprises, is USB-2.0 controlled. These lab or desktop type instruments collectively cover a frequency range of 25 MHz to 27 GHz, and are useful in combination with other instruments for testing equipment during their design and development phases. As they are extremely compact, engineers can use them virtually anywhere, even while testing and conducting measurements in the field.

The accompanying USB cable supplies control and power to the synthesizer from a laptop, which also doubles as the measurement interface. The synthesizer connects to the device under test through an accompanying coaxial cable with a male MMCX connector on one end and a female SMA connector on the other.

The PE11S390X family consists of six models, with the low end in the group covering 35 MHz to 4.4 GHz, and the high end covering the range of 24 to 27 GHz. At an offset of 100 kHz, the various models have a phase noise ranging from -75 dBc/Hz at 27 GHz to -103 dBc/Hz at 4.4 GHz. Users can adjust the output power from -20 to +18 dBm, in steps of 1dB.

Although the synthesizers operate from an internal clock of 50 MHz, users can operate them from an external reference between 10-70MHz. Other features available are synchronization to other test instruments, with LEDs indicating the USB connection, PLL lock, and RF power output. Users have the choice of controlling the synthesizers through Windows, Mac, or Linux platforms, and each has its own non-volatile memory for storing the last setup. All units operate from 0°C to +55°C.

Fairview Synthesizers

The USB controlled, phase locked loop (PLL) frequency synthesizer family from Fairview Microwave Inc. offer high levels of signal integrity, superior frequency stability and accuracy, and exceptional phase noise characteristics. Fairway family of synthesizers is useful or applications involving bench top test and measurements of microwave radios, signal generators, and equipment involved with electronic warfare.

With the GUI command control and DC power coming through USB-2.0 connectors from a PC or laptop, these rugged and compact synthesizers cover a broad range of frequency bands from 25 MHz to 27 GHz. Users can control the power output up to +19 dBm and adjust it down by 50 dB in 1 dB steps. With phase locked loop speeds of 1ms, the synthesizers offer phase noise as low as -108 dBc/Hz at an offset of 100 MHz.

What is E-Smog and How to Detect it?

Many people claim advancement in technology and the proliferation of electronic devices is creating a sea of electromagnetic waves around us, and this eSmog is actually a cause for many of the illnesses we are afflicted with nowadays. While eSmog causing bad health is up for debate, some people seem to be more sensitive to it than others are. However, the presence of electromagnetic waves around us cannot be ruled out, with greater concentrations around devices such as computers, mobile phones, Wi-Fi routers, cordless phone bases, and in fact, anything electronic and powered up. Therefore, an instrument that measures the level of electromagnetic fields around it is in order.

Today, it is practically impossible for us to live life without our electronic devices and everyday technology that produce electromagnetic fields. Although we cannot see the electromagnetic fields that surround us, an instrument that can measure its presence is useful for us to know, say, whether a brick wall has reduced the level, and to what extent.

We all need our Wi-Fi, Zigbee, Bluetooth, television, radio, mobile phones, and other gadgets. To know the level of eSmog each of them is producing, you can use the kit TAPIR—an eSmog detector. You can assemble this tiny instrument from the seven small PCBs in the kit. TAPIR comes with an antenna and two types of electromagnetic detectors.

The kit has a PCB panel, actually made of seven parts. You can assemble the PCBs and make them form the enclosure for TAPIR. The PCBs are numbered—starting with the top piece, the left sidepiece with a switch, the bottom piece with the components, the right side piece with the headset connector, the negative battery connection piece, the positive battery connection piece, and the end piece. A headset plugged into the connector allows the user to hear the device detecting eSmog. The intensity of sound increases with the level of eSmog TAPIR detects. You need a single AAA battery to power the kit.

TAPIR—acronym for Totally Archaic but Practical Interceptor of Radiation—is a wideband ultrasensitive eSmog detector. Once you have connected it to the antenna and the headphones, and switched it on, you can move it around an electronic device. This allows you to hear different noises depending on the type and frequency of the field the device is emitting.

Making the two antennae for the TAPIR is important for it to function properly. All around us, there are two types of electromagnetic fields—the E-field or electrical field, and the H-field or the magnetic field—and two separate antennae are necessary to allow TAPIR to detect the two fields.

The E-field antenna consists of a length of solid insulated wire. The kit includes the wire, and you will need only half of it to form the antenna. Insulate one end of the wire with heat-shrink tubing and bend it to form a loop. At the other end of the wire, solder the cinch connector shell to complete the antenna.

A coil is enclosed with the kit, and you can solder this coil to two pieces of insulated wires. Solder the free ends of the wires to the second cinch connector, and your H-field antenna is ready.

Accurate Power Monitoring with LTC2992

Linear Technology Corporation, now a part of Analog Devices, Inc., has recently placed on the market a power monitoring IC, LTC2992, which offers a wide-range, dual monitoring system for current, voltage, and power for 0-100 VDC rails. The IC is self-contained and does not need additional circuitry for functioning.

Users get a variety of options for operating the LTC2992. For instance, they can derive power from a 3-100 VDC monitored supply, or from a 2.7-100 VDC secondary supply, or from the shunt regulator on-board. Therefore, when monitoring the 0-100 VDC rail, the designer does not have to provide a separate buck regulator, a shunt regulator, or an inefficient resistive divider.

Within the LTC2992 are a multiplier and three Analog to Digital Converters (ADCs) of the delta-sigma type. Two of the ADCs provide measurements for current in each supply, while the third ADC measures voltage in 8- or 12-bit resolution and power in 24-bit resolution. The wide operating range of the LTC2992 makes it an ideal IC for several applications such as blade servers, advanced mezzanine cards, and 48 V telecom equipment.

Users with equipment using negative supply or supply greater than 100 VDC can make use of the onboard shunt regulator. The LTC2992 has registers that one can access with the I2C bus, and it uses these registers to store the measured values. It can measure current and voltage on-demand or continuously, using these to calculate the power, and stores this information along with maximum and minimum values in the registers.

The LTC2992 has four GPIO pins, which the user can configure as ADC inputs for measuring neighboring auxiliary voltages. Over its entire temperature range, the LTC2992 takes measurements with only ±0.3% of the Total Unadjusted Error (TUE). For any parameter going beyond the thresholds programmed by the user, the LTC2992 raises an alert flag in the specified register and on the specified pin. This is according to the alert response protocol of the SMBus.

The I2C bus on the LTC2992 operates at 400 kHz and features nine device addresses, a reset timer for a stuck bus, and a split SDA pin for simplifying the opto-isolation for the I2C. Another version of the IC, the LTC2992-1 offers users an inverted data output pin for the I2C. This makes it easy for the users to interface the IC where the opto-isolator has an inverting configuration.

The ICs, LTC2992 and LTC2992-1, are both available in automotive, industrial, and commercial versions. Their operating temperature ranges are -40°C to 125°C for automotive, -40°C to 85°C for industrial, and 0°C to 70°C for commercial applications. Linear Technology Corporation makes both versions of the IC in packages of 16-lead MSOP and 16-lead 4 x 3 mm DFN, and both versions are RoHS-compliant.

Most electronic applications require monitoring of current, voltage, and power at board level. Knowing the key system parameters provides valuable feedback, allowing users to monitor the health of their systems and make intelligent decisions. They help in determining whether a system is operating properly, efficiently, or even dangerously. Users can choose for various types of monitoring ICs, ranging from hot-swap dedicated power ICs to temperature monitors.

What is ReRAM?

DRAM is a popular memory technology regularly in use in almost all computers and smartphones today. However, resistive RAM or ReRAM is an upcoming parallel technology of high-density storage class memory, whose performance, researchers claim, has now reached very close to that of DRAM.

According to 4DS Memory Limited, who patented their Interface Switching ReRAM, have made substantial changes to the architecture of their product. They claim this has resulted in substantially improving read access so that the speed of ReRAM is now comparable to that of DRAMs. According to Guido Arnout, company CEO and Managing Director, the development has presented the company with several opportunities.

So far, most memory technologies have faced inherently high errors of bit rates. This includes ReRAMs as well, with randomly large cell current fluctuations to blame. Although manufacturers do include techniques for error correction to retrieve data reliably, the activity is time consuming and affects read access times negatively and cripples read speed.

After making the changes, 4DS could not find any large fluctuations with their Interface Switching ReRAM even with an extensive study. They claim this indicates the memory needs minimal error correction. Therefore, the high-density storage class memory how has effective read speeds comparable to that of DRAM. According to Arnout, the company has also scaled their memory products to 40 nm, with a significant increase in endurance.

Initially, 4DS was trying to create a storage class memory to compete with NAND flash. However, with prices of NAND flash dipping fast, the opportunity for ReRAM is now stationed between DRAM and flash. With the difference in price between DRAM and flash growing regularly, the opportunities for 4DS are also getting larger.

4DS uses a different approach for developing their Interface Switching ReRAMs. Rather than use the regular filamentary technology, 4DS uses a technique that allows cell currents to scale with geometry. According to 4DS, they use smaller cells that yield lower cell currents, and these currents can flow more reliably through narrow on-chip wires, which are necessary for achieving higher densities. However, lower cell currents also means the memory suffers longer latency, and 4DS, through extensive measurements and analysis, had to optimize the cell currents so that the latency matched that of DRAM in a high-density storage class memory.

Even short cell latency is not adequate. In reality, latency is actually made up of the sum of the inherent memory latency added to the time required to detect and correct any read errors.

The Interface Switching technology from 4DS reduces the switching region from the influence of random irregularities. That makes the latency of the new Interface Switching ReRAM the dominant factor rather than the overhead of its error correction.

SanDisk had predicted a decade earlier that ReRAM would eventually replace the NAND flash. Now, with the Interface Switching ReRAM, 4DS is looking at a tier of storage class memory that will enable data centers to deliver more content on the Internet at a faster rate and efficiency. After proving the concept of its Interface Switching ReRAM, 4DS is now focusing on scaling it for achieving decent yields.

Oscilloscopes Lose their Faces

The word oscilloscope usually conjures up images of a box with a display. Earlier, oscilloscopes were bulky devices with a display made of a cathode ray tube, but later the models became sleeker, and came with a liquid crystal display. Another difference was in their method of measurement. Whereas there were analog units earlier, later models sported an analog to digital converter inside, which converted all analog signals to digital data. Nevertheless, the display continued to be a part of the oscilloscope.

However, Tektronix now has unveiled a low-profile oscilloscope that has lost its face—the display. The MSO5 series of oscilloscopes from Tektronix has a faceless version aimed at Automated Test Equipment (ATE) applications. It is a low-profile version competing with modular oscilloscopes and digitizers.

Suitable for automated tests or for monitoring machines, the low-profile MSO58 of the MSO5 series, is a rack mountable unit. All its specifications match those of its regular benchtop cousins. It has eight analog inputs with FlexChannel features, which allow eight digital channels to substitute the analog channel with a 1-GHz bandwidth on all of them. The real-time scan rate for all the channels is 6.25 Gsamples/sec with 12-bit ADCs on each channel, but a high-resolution mode allows the resolution to increase to 16 bits and 125 Msamples/sec. That makes the effective number of bits as 7.6 at 1 GHz, or 8.9 at 20 MHz, with a record length of 125 Msamples/channel.

Software within the faceless oscilloscope can help with jitter and serial bus analysis, channel math and Fast Fourier Transformations (FFT). For bench and debugging applications, the software also provides cursors. There are six USB host inputs, on USB input for a device, a LAN port, a Display Port, DVI-D port, SVGA output port. However, the device lacks GPIB connectivity.

As the internal hardware and functionality is identical in both the benchtop and the faceless versions of the MSO5 series oscilloscopes, any automation code for production for device validation and characterization works interchangeably. The six USB host ports may lead one to believe the low-profile oscilloscope could be useful as a system controller. However, the operating system of the unit is a closed Linux version, and a separate PC is necessary for automated use.

The six USB device ports can help in creating a network, to which, one can add more accessories such as an external storage or other instruments. If you have additional MSO5 low-profile units to work together, you can also add a USB hub or an Ethernet switch. Unfortunately, for those using GPIB primarily, these units do not come with a GPIB port.

It is very easy to configure any input of the low-profile faceless oscilloscope as one analog or 16 logic channels. Therefore, one can mix and match the configuration to change it as necessary. For instance, channels 1 and 2 can be analog, while the channel 3 caters to 16 logic inputs.

Bandwidths for the MSO5 series oscilloscopes are 350 MHz, 500 MHz, 1GHz, and 2 GHz. However, one can upgrade any model at any time to operate at any bandwidth.

Using Hall-Effect Type Sensors Effectively

We are familiar with appliances such as wine coolers, freezers, and refrigerators. They keep out beverages and food cold, extending their useful life. Most often, these appliances have lights that illuminate the insides when the user opens their doors. Since the lights only need to be on when the user opens the door, usually, the designer of such appliances place a sensor to detect the opening and closing of the door.

A sensor of the Hall-effect type can detect the position of the door. In refrigerators, the position of the sensor is within the frame, while a permanent magnet is placed on the door directly opposite the Hall-effect type sensor. For refrigerators with multiple doors, each door needs a magnet and for the detection, each magnet must have a corresponding sensor placed in the frame. The adjustment of proximity of each Hall-effect type sensor and magnet pair is such that the Hall-effect type sensor detects the magnet only as the door closes completely.

An electronic control unit inside the electronics assembly of the refrigerator monitors the output from the Hall-effect type sensors and turns the lights on or off as necessary. Hall-effect type sensors can detect a variety of proximity- and position-sensing applications such as when there is a need to discover the proximity of a moving part relative to a sensor placed in a fixed location.

For instance, Hall-effect type sensors can help to stop the motor opening or closing a garage door once the door has reached its desired position. Typically, this needs a system of two Hall-effect type sensors to detect the two dominant positions of the door—open or closed. Each sensor also needs a corresponding magnet to trigger it.

The position of one of the magnets on the drive chain of the garage door opener places it directly next to the sensor that detects a closed door. The position of the other magnet, also on the drive chain, is such that the drive chain brings it next to the other Hall-effect type sensor as the door opens completely.

Hall-effect type sensors are preferable to other sensors such as reed relays, as the former has no moving electrical contacts, resulting in long life and improved reliability. Other applications that use Hall-effect type sensors effectively are vending machines, security locks on doors, vacuum cleaners, washing machines, dishwashers, and similar applications requiring door- and lid-position sensing.

A flow switch is another application that benefits from the use of a Hall-effect type sensor, which detects the motion of a piston, paddle wheel, or a valve fitted with a permanent magnet. For instance, this arrangement suits tankless water heater units, where the flow sensor has a permanent magnet fixed to a piston. The increasing presence of water pressure in the system moves the piston and its associated magnet near to a permanently positioned Hall-effect type sensor. This causes the output of the Hall-effect type sensor to change and it signals the presence of flowing water.

Similarly, a turbine can have a magnet attached to its blades. As the blades rotate, the magnet passes by a fixed Hall-effect type sensor. The speed at which the blades rotate is proportional to the fluid flowing through the turbine.

A Bench-Top Reflow Soldering Machine

You can easily solder a board with leaded components if you have a hand held soldering iron. Another method of soldering several leaded components in a short time is to pass the board through a wave soldering machine. However, component manufacturers are moving away from leaded components to making more of leadless components, and the soldering technology has had to follow through.

Soldering leadless components or surface mount components requires a different technique than solder wire and soldering iron. Usually, this needs a reflow oven. The process of soldering surface mount components involves applying solder paste to the pads on the board, carefully placing the components in their designated places on the solder paste, and passing the mounted boards through a reflow soldering machine.

Using surface mount technology has its own advantages over the use of through-hole components. Apart from the several electrical, mechanical, cost, and size benefits of using surface mount components, the use of a reflow machine for soldering the whole board within about three minutes is enough reason for switching over totally to surface mount technology.

Selecting a bench-top reflow soldering machine requires looking at different aspects. A practical wide drawer type design makes it easy to load and unload boards. A large window on the side should allow you to see inside the machine when soldering. Modern reflow machines usually feature digital controls along with a touch controlled display panel. Some even offer a USB port allowing you to connect to a computer for a more detailed control.

Reflow soldering machines are available in different sizes, the larger ones allowing a large enough surface to solder several boards at a time. However, larger surfaces are only useful if the machine can distribute the heat evenly over it, since you would like to have all the boards soldered properly, and not just the ones in the middle. This is true for large boards also, and an even heat distribution helps to solder all the parts in the same way.

For evenly distributing the heat, reflow soldering machines use full-width quartz infrared lamps, followed up with an air circulation system. They are set up in a special way to enable a minimum temperature difference over the soldering area. Most manufacturers of soldering machines include PCB holders with brackets that do not influence board heating.

An important factor influencing soldering of surface mount components is the thermal profile. As the board passes through different regions of the reflow machine, it must gradually heat up to the proper temperature to enable soldering, and subsequently, cool down at a defined rate. As the board remains within the machine for only a definite time, the temperature variation over time defines its thermal profile.

Most modern reflow soldering machines are computer controlled and allow creation of elaborate thermal profiles by adjusting the speed at which the board traverses the entire length of the machine and the temperatures of different zones during its journey. Users can define up to three preheating zones, a reflow peak, and a cooling down phase. You can also store a few profiles so the machine can be operated in a stand-alone manner.