Temperature-Controlled Soldering Irons

Chances are you learned to solder using a cheap pencil-type soldering iron. The bad news is that not only is this type of soldering iron a lousy tool to learn with, pencil-type irons are not recommend for any important solder work, and the reason is simple: a pencil-type soldering iron does not have a thermostat, which is to say it’s always on, making the soldering iron hot to the touch; in addition, a pencil-type iron will not heat, for example, components very well — if the iron had sufficient power, it would destroy itself, since it is on all the time.

As if that was not enough, the soldering iron tip is typically hotter than it needs to be, so it will not cool too quickly when you apply the solder, meaning that the solder on the iron’s tip oxidizes rapidly. The excessive tip heat results in poor thermal conductivity, making the soldering process more difficult. Because the soldering iron tip cools rather quickly when you do finally apply solder, the soldering iron may not have enough heat capacity to heat the circuit board enough to make a proper solder joint, unless you hold the iron to the board for a longer amount of time. Time is not on your side when you solder: the longer you hold the soldering iron to the circuit board, the greater the chance that you will damage components or the board itself.

For the reasons stated above, you should consider investing in a temperature-controlled soldering iron. These irons have a thermostat that switches off the heater once the selected temperature is reached, meaning these irons are capable of housing a more powerful heating element, which speeds up the heating application process. When you are not using the iron, the element uses just enough power to maintain the temperature setting and will not overheat, thus keeping the soldering iron tip in better shape. Another benefit of using a temperature-controlled soldering iron is that you can set the appropriate temperature for the type of solder you are working with — for example, you will need more heat for lead-free solder. You can also turn down the temperature when you are soldering delicate or heat-sensitive parts and turn it up when you are working on large or heat-conductive terminals.

Although the sophistication of a temperature-controlled soldering iron will cost you a little more, I think you will find it worthwhile in the long run. This type of soldering iron is especially useful for beginners because it will really speed up the learning process. Some soldering irons may at first glance appear to be temperature-controlled, but they may only be adjustable; because they are open-loop the temperature is not actually controlled at all.

Soldering Safety

If you are working on an electronics project, you are probably soldering. Soldering can be dangerous: solder produces toxic fumes, your soldering iron is extremely hot, the solder gets very hot as well, and you may get air pockets or impurities that can pop as you heat the solder, sending molten solder flying unexpectedly and unpredictably. Because of these potential hazards, you need to follow some rules while soldering.

1) Wear goggles to protect your eyes. You must be careful when you trim leads or solder dross because a flyaway could injure you and others working in the vici

nity.

2) Never inhale fumes while soldering. Always work in a well-ventilated space, preferably with a fume extractor.

3) You must return the soldering iron to its stand (if you have a soldering station, it will be built-in) when you are not using it — do not leave it sitting on your workbench for any amount of time. The soldering iron tip is around four hundred degrees Celsius, so be careful; avoid touching wire insulation, plastic, and all other nearby flammable materials with the soldering iron. If you won’t be using the soldering iron for a few minutes, switch the soldering station to standby or turn off your soldering iron. Once you have finished soldering, turn off the unit and/or unplug it.

4) Another important way to avoid nasty burns is to use helping hands, clamps, pliers, tweezers, or a circuit board vice to hold your components. Ensure that your arms and legs are covered to avoid being burned by splashed solder.

5) Keep food and drink away from the working area. Traditional solder is a tin/lead alloy, and the lead is toxic. Flux is used to help metal pieces stay soldered together, and it is both acidic and toxic: flux will damage clothing and cause acid burns to your skin which, if they occur, you should immediately flush with water. If you spill any flux, clean it up immediately. Be sure to wash your hands after soldering.

6) Always thoroughly wash your hands after you have handled flux or leaded solder. Use lead-free solder — if you can — to reduce potential hazards.

7) After you’ve finished soldering, completely clean the area and discard any leftover lead and silver solder as well as dross in a lidded container, and then label the container (e.g. “Solder Waste”). Contaminated rags and solder sponges should be discarded as hazardous waste.

A Digital Storage Oscilloscope (DSO) for under $70.00

The Hantek 6022BE  Digital Oscilloscope is a fully functional Digital Storage Oscilloscope (DSO) priced at less than $70.00. This unit is designed to operate with a personal computer which greatly reduces the cost of manufacture by using the Computer Screen as the display and the keyboard as the function controls.

The Hantek 6022BE  oscilloscope features a 20 Mhz bandwidth with a 48 MSa/sec sampling rate, which is suitable for general electronics use. This provides sufficient capability for viewing a multitude of waveforms encountered in design, servicing, and educational environments.

Although this model does not have external triggering c

apabilities, it does not limit the usefulness since Channel 2 could be used as an external trigger input. The oscilloscope features various trigger modes and settings, including auto, normal and single.

Even though this is a low cost unit, it still features various mathematical operations that may be performed on the waveforms applied to the two channels. The operations available are Addition (CH1+CH2), Subtraction (CH1-CH2 or CH2-CH1), Multiplication (CH1 * CH2), Division (CH1/CH2 or CH2/CH1), and Fast Fourier Transform (FFT). The FFT operation is useful for observing the frequency content of the waveform.

The Hantek 6022BE  Digital Oscilloscope was found to be easy to use and included features not normally found on units in this price range. The unit performed at or better than the published specifications through all of the available functions. If higher Bandwidth is required, Circuit Specialists offers models ranging from 20 Mhz up to 200 Mhz.

Caring for Your Soldering Iron Tip

Most contemporary soldering iron tips are made of a copper core surrounded by iron that is nickel- or chrome-plated. The plating on the chisel’s tip is removed, thus exposing the iron cladding, and solder doesn’t stick to the nickel/chrome. Solder will, however, stick to the soldering iron. Keep the tip coated with a thin layer of tin so that it will not rust and so that you receive the optimal heat at the tip, which will in turn extend the life of the soldering iron tip as well as improve performance.

Because solder can build up on your tip and reduce heat transfer, which makes it more difficult to solder, be sure to use high-quality solder. Note that 60/40, 50/50, 63/37, and lead-free solder have different working ranges. Keep the tip of your soldering iron clean while you work: wipe the tip on a damp sponge (if you have a soldering station you should have one built-in) to keep it clean and ensure maximum heat at the tip. Alternatively, you can use metal mesh pads to clean the tip of your soldering iron.

While you want to keep the tip clean, excessively wiping it on a damp sponge can lead to premature tip failure, because the tip temperature will rise and fall dramatically, causing the metal to expand and contract. This cycle will cause the metal to fatigue and the tip will eventually collapse. The more you wipe the soldering iron tip, the more you stress the metal.

Flux is corrosive, so don’t try to clean the tip by dipping it in flux. Also, never clean with sandpaper or other abrasive materials. Minimize tip maintenance by using a quality solder with high tin content and high-purity metal. When you finish a soldering session, clean the tip, flood the tip with preferably 63/37 or 60/40 solder, wipe it clean again, and unplug the soldering iron in order to flush and re-tin the tip, which protects it from oxidation and corrosion.

You can keep the tip from seizing (i.e. becoming stuck in the barrel) by loosening the nut or screw securing it. It’s easy to damage the heating element when you try to remove a seized tip. Make sure the tip is properly seated when reinserting the tip.

If you blacken your soldering iron tip and you can’t clean it with your sponge, you can use a tinning block or a brass brush. Tinning block is a self-ammoniac which you use by rubbing the tip of your hot soldering iron through a small amount of flux you place on the block. You then wipe the tip on a damp sponge to remove the debris. If your tip is especially dirty, you may have to repeat this process several times. Keep in mind that tinning block is abrasive and frequent use will wear away the iron cladding prematurely, thus exposing the copper core and ruining the tip.

Frequency Counter Primer

Frequency counters are easy to use: simply turn on the device and apply the signal to the input. You can use your frequency counter and timer to measure a variety of signals including digital logic signals, radio frequency, and even microwaves. Because of improvements in technology, frequency counters and timers enable you to measure time intervals and frequency, which have an inverse relationship.

You’ll need to apply the signal to the input to measure a time interval or frequency. The next step will be to select the timebase interval, which commonly has the options of point one, one, and ten second(s). These options refer to the time over which the frequency counter gate opens and passing pulses are counted; for example a gate time of one second will count one million pulses for a one megahertz signal or, if five pulses are counted with a gate time of one second, the frequency will be five hertz.

Your frequency counter counts the transition every time the signal passes in the positive direction through the device. More pulses are counted at higher frequencies as you can see from our the example above in which five pulses are counted.

You’ll get more accurate results with longer gate times. Let’s use the previous example with a gate time of point one second for five pulses and a fifty hertz signal. The handheld frequency counter can’t tell the difference between a fifty hertz and fifty-five hertz signal. To get a more accurate reading you can use a one second gate time, thus enabling fifty-five counts for a fifty-five hertz signal.

While longer gate times improve accuracy, your choice of gate time will normally depend on how quickly you need updates for the frequency. Despite the benefits to accuracy longer gate times can slow testing to too great an extent. Because of these tradeoffs in time versus accuracy, you’ll usually use shorter gate times unless you need a high level of accuracy for a particular test.

Multimeter Features Guide

There are a number of different features that differ from one multimeter to the next, some of which you’ll often use and others you may never use.

The most important feature is continuity, which allows you to test whether two things are electrically connected. Continuity testing with a peizo buzzer enables you to determine if your soldering is good, a wire is broken in the middle, and something isn’t connected in addition to allowing you to reverse-engineer or verify a design to a schematic.

Some other important features are resistance testing down to ten ohms or lower and up to one megaohm or higher, direct current voltage testing down to one hundred millivolts or lower and up to fifty volts, alternate current testing down to one volt and up to two hundred volts, and diode testing.

Because it’s easy to forget to turn off your multimeter’s power, auto-off is a great feature to have, which you rarely see on budget multimeters. Regardless of this feature you should get in the habit of turning off your multimeter after you finish using it.

If you know how to use it autoranging is a helpful feature and, typically, autoranging multimeters are of higher quality and have more features than simpler multimeters. Keep in mind that with some systems the current or voltage will be too sporadic for the autorange feature to keep up. Some users dislike autoranging because it slower and less precise.

Other optional but useful multimeter features are alternate and direct current testing, a stand for keeping the multimeter upright, a hold function to keep the maximum value on the screen enabling you to use the probes without staring at the screen, and common battery types (such as a nine volt or AAs).

Back-lit LCD multimeters are nice, but chances are you won’t be measuring circuits in the dark. If you need a multimeter that is visible in low light then by all means look for a back-lit model.

You don’t really need fancy probes for you multimeter — just some sturdy, reasonably-priced ones. Your leads will break down over time, generally at the flex point; however, probes are relatively inexpensive, so when you do break a probe, which you eventually will with enough use, you’ll be able to replace it for around five dollars.

Some features you’ll seldom use include a frequency counter, capacitance testing, inductance testing, duty cycle, transistor beta meter, and temperature probe.

DIGITAL MULTIMETER TEST ENVIRONMENTS

While digital multimeters are still commonly used in benchtop testing, there are now a number of interconnect options for system integration; e.g., some multimeters offer hobbyists and engineers alike USB interfaces and general purpose interface buses for control via PC using test commands. Certain LabVIEW drivers allow one to integrate one’s multimeter into a larger test system. Then there are front-panel thermocouple inputs which allow one to connect directly to many prevalent temperature measurement sensors.

Indicating a multimeter’s susceptibility to noise, digital multimeters have specifications for normal mode rejection ratio and common mode rejection ratio with common values of over sixty decibels and one hundred twenty decibels. The noise produced by one’s multimeter is particularly important when measuring low signal levels, and electromagnetic interference standards influence compliance levels.

Because of its influence on throughput, a digital multimeter’s measurement speed — typically displayed as readings per second at a specific resolution level — is especially important in production environments.

A number of modern multimeters have resolution levels that one can program, thus simplifying balancing speed and accuracy. The integration period, which is the amount of time when a signal is sampled by the multimeter’s analog-to-digital convertor, is typically displayed in number of power line cycles; number of power line cycles made up of integer multiples — one, five, ten, etc. — will reduce the fifty/sixty hertz line pickup, which is the most common type of noise. One will have greater noise reduction with a larger number value with the caveat that measurementS will take longer to complete.

The number of analog-to-digital conversions averaged for each reading, or digital filtering, can stabilize readings with excess noise but, again, this will slow measurement times.

One’s multimeter measures internal voltages in order to retain stability and accuracy with temperature changes over time when a multimeter’s autozero is used, but overuse of autozero will negatively impact the multimeter’s reading rate. Throughput can be increased by disabling autozero, performing it at certain intervals, or programming the multimeter to use autozero during the load/unload cycle.

Speed specifications like range changing speed, autorange time, and function changing rate might also affect throughput, and hardware triggers are generally faster than software triggers. Certain digital multimeter’s have a microprocessor dedicated to triggers which can significantly reduce latency. Setting or response time is also important when one is testing high-impedance devices.

Speedy and accurate switching is notably important in production test environments, because hundreds or even thousands of devices have to be tested every shift, and newer models support hundreds of multiplexer channels or thousands of matrix crosspoints.

PRINTED CIRCUIT BOARD MATERIALS & APPLICATIONS

Using different printed circuit board (PCB) materials will result in different circuit board specifications and prices with regard to PCB prototyping and production. Certain one- or two-layer boards need what is known as pre-preg core — which is a material made from fine layers of fiberglass that is pre-impregnated with a bonding agent or metal core — or several layer boards using two or more kinds of cores for construction. Board thickness varies from a few millimeters thick, for flexible boards, to as much as a quarter inch thick, for heavy burn-in boards. Core materials typically resemble thin double-sided boards with dielectric materials (e.g. fiberglass) as well as copper foil on each side, and they generally come in predetermined thicknesses.

FR4 is the most commonly used type of substrate for circuit boards and is made from a glass-fiber epoxy laminate. FR4 has higher temperature coefficients and lower dielectric constants — e.g. FR4 has a starting thermogravimetry (TG) of one hundred forty degrees Celsius, FR4-06 has a TG of one hundred seventy degrees, and the temperature increases as the family number increases.

Prototypes using metal core, which has impressive heat elimination, are quite popular for light emitting diode (LED) circuit boards. The metal core is an efficient heat sink and keeps the LEDs operating at safe temperatures. One section of a metal core printed circuit board prototype has a metal base, a non-conductive layer (usually aluminum), a copper circuit layer, integrated circuit (IC) components, and a solder mask.

Polyimide printed circuit board prototypes, which are tougher than FR4, can sustain significantly hotter temperatures, making them perfect for most electrical insulation applications. The polyimide is made up of a silicone adhesive and a polyimide film designed to withstand higher temperatures and will protect edge connectors, gold edge fingers (during wave soldering), and reflow soldering (during circuit board assembly). Polyimide can be distinguished from other boards by its distinctive brown color.

Polytetrafluoroethylene (PTFE) or woven glass base circuit board materials necessitate special drilling procedures because Teflon is much softer than, e.g., FR4. These types of materials are far more common than they once were. PTFE/woven glass base materials provide rapid growth of applications operations and easily meet high-frequency demands, and they consistently perform well.

You can also use Arlon materials for longer operating lives at high temperatures, or Isola range circuit board prototypes for broadband circuit designs requiring faster signal speed or better signal fidelity.

USING AN OSCILLOSCOPE ON AUTOMOBILES

A digital storage oscilloscope makes it easy to visualize alternating current electrical signals in an automobile. Oscilloscopes have several electrical inputs and control knobs as well as a liquid crystal display (LCD) screen for displaying the signal.

Generally automotive oscilloscopes are used in manufacturing applications by engineers to set electrical signals to the right form. They are also frequently used in garages by mechanics to test the engine’s components for faults. In addition oscilloscopes are increasingly being used by do-it-yourselfers and those looking to make their own automotive repairs. Some examples of electrical signals that one might observe with an oscilloscope are the ignition sequence and the throttle position sensor’s output.

Let’s take a look at how you can use your oscilloscope on your automobile.

Step One

First you’ll need a coaxial cable, which you will connect between the car’s output that you are testing and one of the oscilloscope’s inputs. Most simple digital storage oscilloscopes have two inputs, typically labelled A and B. It doesn’t matter which input you use. You’ll switch the input on by, e.g., pressing either the A or B button.

Step Two

Next you’ll alter the volts/division control in order to change the vertical scale as well as the number of volts for each division. You won’t be able to see the electrical signal clearly on your oscilloscope’s display  until you’ve adjusted the settings appropriately.

Step Three

Now it’s time to adjust the oscilloscope’s time/division (also known as timebase) control which changes the number of times each horizontal division is shown. When you know the electrical signal’s frequency you can accurately calculate the time/division. The time for a single period is T=1/f (with f being the frequency). Then you’ll set the time/division to the calculated value using the equation above.

Step Four

The last step is to adjust the vertical position control, which will move the signal up or down on the oscilloscope’s display. Your goal is to center the signal.

By following these four simple steps you can use your digital storage oscilloscope to observe your automobile’s electrical signals.

ARBITRARY WAVEFORM GENERATOR SIGNALS

Used to test various circuit topologies, an arbitrary waveform generator (or AWG) can be used as general-purpose function generator as well as a waveform generator. Let’s first address the difference between a signal generator, function generator, and an arbitrary waveform generator.

Signal generators produce high-fidelity sine wave signals that range from low frequencies to many gigahertz (GHz). Features of signal generators include attenuation, modulation, and sweeping.

Function generators are lower-frequency instruments which produce sine, square, pulse, triangle, and ramp waveforms from direct current up to a few megahertz (MHz) and usually cover a wide range of voltage.

Arbitrary waveform generators, which we’ll be focusing on below, are high-flexibility signal sources that can generate any arbitrary waveform constructed from point-by-point in digital memory, and these constructed waveforms are converted into analog signals with the AWG’s digital-to-analog converter (DAC), which operate at clock rates up to a few gigahertz (GHz). Because AWGs have built-in algorithms that generate standard functions, they can stand in as an ordinary function generator.

Types of Arbitrary Waveform Generator Signals

There are four categories of waveforms that an arbitrary waveform generator can create: standard and advanced functions, arbitrary waveforms, and waveform sequences. The standard functions category consists of pulse, ramp, sine, square, and triangle waveforms which are used in such applications as baseband, audio, sonar, ultrasound, and video components as well as circuits. Frequency response characterization, digital logic generation, device linearity characterization, and direct current-offset signal generation tests can be performed with an arbitrary waveform generator.

The majority of arbitrary waveform generators feature advanced functions including multi-tone, cardiac, noise, and much more that are used by specific industries for unique applications — e.g., cardiac and haversine signals are commonly used in medical device tests. Due to the abrupt transitions in the signal, standard pulse waveforms excite the device under test with extensive harmonic content; and other kinds of pulse waveforms have smooth transitions which shape the harmonic content for certain applications. Some examples are sinc and exponential pulses.

Sinc pulses, which are shaped with bandwidth-limited frequency spectrums, are used to characterize or excite communications channels that have limited bandwidth capability. Exponential pulses can simulate various physical phenomena, e.g., a resistor-capacitor charging circuit.

DIGITAL STORAGE OSCILLOSCOPES: CHOOSING THE RIGHT BANDWIDTH

Because there are hundreds of models available with different specifications at a wide variety of prices, choosing the right oscilloscope can be intimidating and confusing for many engineers and technicians. In this article we’ll look at a few aspects of digital storage oscilloscopes that are of particular importance in order to help you avoid a costly mistake.

Some things to consider before we get into the specifics of bandwidth are: where you’ll be using the oscilloscope, how many signals you’ll need to measure at one time, the minimum and maximum signal amplitudes you’ll be measuring, the highest frequency signal you’ll potentially measure, whether your signals are repetitive or single-shot, and whether you need to view signals in the frequency domain (i.e. spectrum analysis) and the time domain simultaneously.

Bandwidth

Bandwidth is the maximum signal frequency that can pass through the front-end amplifiers and the oscilloscope's bandwidth must be higher than the maximum frequency you’d like to measure. However, sufficient bandwidth isn’t the only consideration when making sure that a digital storage oscilloscope can capture a high-frequency signal accurately.

Oscilloscope manufacturers seek a certain type of frequency response when designing their instruments and this response is called the maximally flat envelope delay, or MFED. This type of frequency response provides superb pulse fidelity with very little undershoot, overshoot, and ringing. Because a digital storage oscilloscope is made up of amplifiers, attenuators, analog-to-digital converters, interconnects, and relays, maximally flat envelope delay response cannot be entirely realized — think of it more as an ideal.

Please note that the majority of oscilloscope manufacturers define bandwidth as the frequency at which a particular sine wave signal will be attenuated to seventy-one percent of its actual amplitude, i.e. the trace will be twenty-nine percent in error of the input signal.

Your signal will contain high-frequency harmonics if your input signal isn’t a pure sine wave; e.g. a twenty megahertz signal viewed on a twenty megahertz bandwidth oscilloscope will show up as a distorted and attenuated waveform. A good rule of thumb here is choosing an oscilloscope with a bandwidth five times higher than the maximum frequency signal you’d like to measure. The caveat here is that oscilloscopes with high bandwidths are more expensive, meaning you may have to compromise with regard to your oscilloscope’s bandwidth. Some oscilloscopes have bandwidths that aren’t available for all voltage ranges which is why should carefully read through the oscilloscope’s data sheet.

STEPPER MOTORS: THE BASICS

Found in both industrial and commercial settings as a result of their affordability, reliability, durable construction, and high torque at low speeds, stepper motors are brushless synchronous electric motors that work by converting digital pulses into mechanical rotation. Every revolution of a stepper motor consists of a division of steps and the motor is sent a pulse for each step. A stepper motor’s position can be controlled without feedback because stepper motors are able to take only one step at a time and each step is the same size. When pulse frequency increases to a certain point the step movement will turn into continuous rotation with the speed directly related to the frequency of pulses.

There are a number of reasons to use a stepper motor: 1) open-loop control simplifies the motor and makes control less expensive; 2) the motor’s rotation angle is directly proportional to the input pulse; 3) you need precise positioning and reliable repetition of movement; 4) stepper motors have wide operational ranges because the speed is commensurate to the input pulses’ frequency; 5) they have excellent response times with regard to starting, stopping, and reversing; 6) good stepper motors are accurate within three to five percent of a step; 7) when the windings are energized stepper motors have full torque at complete standstill and, when the load is coupled, you can achieve remarkably low speed synchronous rotation; and 8) because stepper motors don’t have contact brushes, they have an exceptionally high mean time between failure.

The three types of basic stepper motors are variable reluctance, permanent magnet, and hybrid — hybrids combine the strengths of variable reluctance and permanent magnet engines. Hybrid stepper motors have toothed stator poles, a permanent magnet rotor,typically  two hundred rotor teeth, and most hybrid motors rotate at under two degrees each step. As a result of their high static and dynamic torque and their ability to run at quite high step rates, hybrid stepper motors are commonly used in a number of different applications including computer disk drives, printers, machine tools, and much more.

Hopefully this brief overview helped you to understand a little bit more about the operation of stepper motors, their characteristics, and some common applications where stepper motors are employed.

USING SHUNTS IN CONJUNCTION WITH DIGITAL PANEL METERS

In the medical world a shunt is a means of diverting, e.g., blood from its typical path to another route. Shunts work in a similar manner in the realm of electronics, allowing current to bypass one point in a circuit and travel to another point.

An example of this would be Christmas lights. Because they are set in series, when one bulb fails the entire circuit goes out. Modern lights prevent this with shunts: each bulb has its own shunt in order to pass the current along, so to speak, when a filament fails.

Circuits are commonly tested for current, resistance, and voltage. Some devices — e.g. ammeters, voltmeters, and ohmmeters — individually measure these parameters. Other devices, like digital multimeters, can test several parameters at once. Digital panel meters are used to measure, display, and record a circuit’s current, resistance, and voltage; but because they are continually subjected to the parameters which they measure, they are prone to damage. However, using panel meters in conjunction with shunts mitigates the risk of damage.

When you combine shunts and panel meters you end up with shunt-resistive circuits which enable you to circumvent predetermined levels of current surrounding a piece of electronic testing equipment. Using a shunt and panel meter together (i.e., a shunt resistor) reduces the excess flow of current through your instruments and helps keep them better protected.

Moreover, combining a shunt and digital panel meter can extend the range of the shunt, which is known as a meter shunt. When you divide current between parallel shunt resistors you increase the range of an ammeter by adding another parallel resistor. Let’s say your meter can only read between zero and one milliamperes but your test requires full-scale detection of one hundred milliamperes. In this situation you can use a shunt to take on the difference between the detection capabilities of your meter and the desired level of full-scale detection. With regard to our example, your shunt would have to be able to handle the remaining current (i.e., ninety-nine milliamperes).

Shunts have myriad uses in electronics testing, but their chief utility comes from their ability to protect delicate equipment and boost the capabilities of panel meters, making shunts exceedingly useful for those who do serious electronic testing.

FUNCTION GENERATOR OVERVIEW

Sometimes a device will not properly respond to electrical impulses and other times a device won’t respond at all. In these situations a function generator is handy for diagnosing the problem. Function generators test the response of various circuits to electrical signals and impulses by releasing voltage patterns of differing frequencies and amplitudes, which are controlled by the operator of a function generator. Function generators are frequently used in conjunction with an oscilloscope, which displays electrical waveforms.

Waves

Function generators allow you to choose the shapes of the output which replicate several mathematical functions: a square wave moves abruptly from high to low voltage; a sine wave gently curves from from high to low voltage; triangle waves move from high to low at a fixed rate (i.e. diagonal lines); and sawtooth waves rise slowly and drop quickly.

Reason to Use a Function Generator

Function generators are a very easy and convenient means of testing electrical devices. You can use a function generator when a device or part of an electrical system malfunctions or stops functioning altogether. You test the device or system’s response to electrical activity by replicating its ordinary impulses using the function generator’s waveforms. When you send a device/system an electrical impulse like the one which it would usually have and the device/system either distorts or fails to accept the signal, you know that your device/system is defective.

Function generators are also used for measuring feedback from musical equipment — amplifiers, microphones, electric instruments, etc. — because the waveforms imitate situations when the device you’re testing will be affected by electricity, enabling you to draw conclusions as to what’s not working right.

Function Generator Use

The first step to using a function generator is (you guessed it) powering it on. Next you’ll connect your lead and ground to your oscilloscope in order to check the controls and make sure the generator is configured to use the waveform you need. After you have the waveform you want you’ll connect the signal lead to the device you want to test and the ground lead to the device’s ground (some devices have a negative lead; connect your ground lead to the negative lead in this case). After everything is set up you can then send impulses to your device. Not only can you control the waveform you send the device, you can also control the volume of the wave as well.

BENEFITS OF PC-BASED USB OSCILLOSCOPES

PC-based USB oscilloscopes, which display signal voltage as two-dimensional graphs and indicate amplitude distortions related to events and frequency, are used by hobbyists and professionals alike for testing hardware and research. Conventional oscilloscopes are typically stand-alone pieces of testing equipment that aren’t readily portable. PC-based oscilloscopes connect directly to your computer’s USB port and enable you to power the device, acquire and store data, and supply record evaluation; these features have given users more options and new techniques when using an oscilloscope.

PC-based oscilloscopes utilize your computer’s hardware — specifically its processor(s) — to display data on the computer’s screen and record that data on the computer’s hard drive or other storage devices. There are myriad modifications that can be done with PC-based oscilloscopes that aren’t practical for stand-alone oscilloscopes.

There are a wide variety of uses for PC-based oscilloscopes. Technicians use PC-based oscilloscopes as diagnostic tools for computer problems and maintenance work on all sorts of electrical equipment. PC-based oscilloscopes are also useful for everything from conducting electrocardiograms (medical professionals) to diagnosing issues with cars (automotive repair).

Modern computer processors are faster than they’ve ever been and their prices are dropping all the time — it’s no wonder that PC-based oscilloscopes are being used more often. In addition PC-based oscilloscopes can do everything that stand-alone units can but cost less and work with just about any computer. Old PCs are often significantly faster and more powerful than many stand-alone oscilloscopes that cost hundreds or even thousands of dollars, meaning that you can pull that ten-year-old computer out of storage, dust it off, and bring it back to life with an oscilloscope.

Furthermore data collected with a PC-based oscilloscope can be quickly and easily stored, shared, or exported as a result of a computer’s word processing and spreadsheet software, storage capacity, and networking capabilities. On top of that PC-based oscilloscopes offer better screen resolution and portability. It’s not hard to see why PC-based USB oscilloscopes have increased in popularity in recent years. Stand-alone oscilloscopes may soon be a thing of the past.

USB OSCILLOSCOPE OVERVIEW

USB oscilloscopes, which allow you to take measurements of electrical impulses and observe constantly varying signal voltages, operate via one of your computer’s USB ports. An oscilloscope measures all detected signals and displays a graph indicating precisely how much impulses change for a specific time period. You will notice several things regarding a single signal: the signal’s frequency, voltage, duration, and the level of alternating and direct current. While standard oscilloscopes are powered by direct electrical connections, USB oscilloscopes derive their operating power from linking to your computer by way of its USB port.

In the past oscilloscopes were used sparingly because of their power requirements, but recent technical developments have led to portable oscilloscopes that can be powered by plugging into a USB port, making these multipurpose tools — which are used in a variety of applications from basic electronics to advanced physics testing and experimentation by hobbyists and professionals alike — standard equipment in many classrooms and laboratories.

The invention of USB-powered oscilloscopes has enabled them to be used in a number of new ways. Because USB oscilloscopes can be powered by a laptop computer, they can be used nearly anywhere. USB oscilloscopes also have the added convenience of quickly and efficiently downloading information to the computer to which it is attached. Another benefit of USB oscilloscopes is that the information they collect is instantly displayed on your computer. As a result of the speed at which information is transmitted to a computer, its easy for all the data taken by an oscilloscope to be shared between several viewers on different computers, which is an advantage for specialists who want to quickly distribute data to colleagues elsewhere.

There are a wide variety of USB oscilloscopes available including basic oscilloscopes for less demanding testing applications and more sophisticated (and expensive) oscilloscopes that feature better specifications, additional capability, and excellent accuracy. This diversity in the USB oscilloscope market makes these powerful pieces of test equipment suitable and cost-effective for a variety of disciplines, including everything from basic production jobs to more technical tasks like research and product development.

USING THE RIGHT OSCILLOSCOPE PROBE

A piece of test equipment’s performance is always limited by its peripheral equipment, and the same holds true for digital storage oscilloscopes. Most people tend to focus on an oscilloscope’s specifications — especially considering that specifications generally determine price — but an oscilloscope probe’s performance is every bit as important. A substandard oscilloscope probe will impair the performance of even the very best oscilloscope.

You want your oscilloscope probe to provide a simple means of presenting the signal on a circuit board or whatever is being tested to the oscilloscope’s input. A standard oscilloscope probe will consists of a probe tip, length of shielded wire, and a compensation network.

Passive probes are the most common kind of oscilloscope probe and there are two noteworthy types of passive probes: X1 and X10. X1 probes present a signal as it exists to your oscilloscope. Ordinarily an oscilloscope’s input impedance is one megohm, but this impedance can load the device you’re testing and distort the waveform. Moreover, an X1’s tip capacitance can be as high as one hundred picofarads. To avoid these limitations and lessen the load on the circuit you’re testing an X10 probe can be used instead. Because an X10 probe has an input impedance of ten megohms and a tip capacitance of around ten picofarads, this type of probe will distort the waveform far less than an X1.

Active oscilloscope probes are another option when you need even greater levels of performance. These probes have very low levels of capacitance and significantly higher input impedances as a result of having an active element quite close to the oscilloscope probe’s tip.

Calibration

It’s very easy to simply plug your oscilloscope probe in and start taking measurements with your oscilloscope; however, your oscilloscope probe needs to be calibrated before you use it to make sure that its response is flat. Almost every oscilloscope has a built-in calibrator for this reason. The calibrator provides a square wave output, and the oscilloscope probe has a small preset adjustor. You connect the probe to the calibrator’s output and manipulate the present adjustor until the shape of the displayed waveform is perfectly square. When the oscilloscope probe’s high frequency response is down the edges of the square wave on the display will be rounded and, if the high frequency response is up, the probe’s wave will overshoot the edges.

This simple adjustment is imperative for ensuring that the oscilloscope probe performs perfectly.

Differences Between Digital and Analog Oscilloscopes

The oscilloscope has been a commonly used piece of testing equipment for over fifty years now and is used by TV technicians and aerospace engineers alike. Oscilloscopes are one of the most frequently used instruments in the field of electronics circuit design, testing, and troubleshooting because they have the ability to graphically depict the waveform, magnitude, and time base of electrical signals on its screen.

In addition it can be calibrated so that the magnitude and frequency can be observed with a great deal of accuracy. Most models also have more than one input, allowing for two or more signals to be observed at once. For these reasons oscilloscopes are invaluable to those seeking to observe the function and operation of electronic circuits in real time. Because electronic circuits operate in a decidedly non-visually way, an oscilloscope acts as a window into its operation.

Early oscilloscope designs were based on analog amplifier circuits which brought the signal’s amplitude to a level sufficient to drive the oscilloscope’s cathode ray tube’s deflection plates. An analog oscilloscope’s built-in sawtooth waveform moved the CRT’s beam from one side to the other and rapidly returned it for a consecutive scan, but these days it needs to be able to trigger at the exact moment of a digital event and it needs to be capable of showing what happens in other parts of the circuit when a digital event occurs (it may or may not be repetitive).

For this reason triggering systems capable of causing the oscilloscope to sweep exclusively at the instruction of the incoming pulse were developed. It was also commonly necessary to synch the horizontal sweep to the digital system’s clock frequency in order to show the digital switching events because timing was and is a high priority for those debugging a logic module.

It’s no wonder that digital oscilloscopes developed into a collection of of electronic circuits when you take into account all the functionality digital devices demanded. Digital oscilloscopes have quickly become very complex instruments that require some of the brightest minds in the digital electronics field for their design and to fine tune their performance characteristics as digital equipment — especially computers — become faster and more sophisticated.