Touch screens work by recognizing the pressure of a finger or stylus and then responding accordingly. For a touch screen to work, it needs a few basic parts. These parts, when combined together, allow the touch screen to work properly. As the cost of touch screens drop, more are beginning to appear on different products ranging from computers to mobile phones.

The first part is the touch sensor. This sensor is placed on top of the actual display screen. The sensor has an electrical current going through it, so when pressure is applied to the sensor, the voltage changes. This change is what is recognized as a touch on the screen and it reacts. So, if you press the Internet button on your phone, the sensor recognized the change in voltage from that area.

This voltage is then passed to a controller within the touch screen. This is how the voltage is then converted into a signal that can be recognized by the small computer within the device. When this signal is changed to computer language, whatever action you wanted to take place does.

There are a few different types of touch screens and they functions differently. The first is known as the resistive. This system sends a current that alters when it passes through an electrical conductive layer. The next type is a surface wave which generates ultrasound waves. These waves are absorbed and a transducer recognizes them.

The final type is the most well known which is called capacitive. This is the one found in an iPhone. Because of the electromagnetic field around humans–a very small charge flows through people at all times–it reacts to other electrical objects. So, the screen of the touch screen has a material on it that absorbs electrical charge. When a finger touches the screen, the charge passes to the phone and then it is recognized by the capacitor. This is why you need to use your finger on an iPhone rather than a stylus.

If you are planning on working on electronic or automobiles that have been manufactured in the past decade, then you will need to be able to use a digital multimeter. Modern multimeters contain three measuring devices in one to include an ammeter, voltmeter, and ohmmeter. The top section of the device will contain the digital read out and it should be able to be viewed in sunlight if you are working outside.
What Are the Parts of a Digital Multimeter?
The parts of a digital multimeter are fairly common across brands. Beneath the digital readout will be the function switch that lets you change the modes that the meter will operate, measure, and display. There are typically eight positions on a function switch that will include three voltage readouts for AC, DC, and low currents, two amperage slots (one for AC and one for DC current), and Omega for measuring circuit resistance.
How Do You Measure Voltage with a Digital Multimeter?
Step 1 – Turn on the device and allow it to cycle through its startup checks.
Step 2 – Turn the function selector switch to the “V=” position in order to measure DC volts.
Step 3 – Connect the red and black leads to the red input terminal marked “VO” and the black terminal marked “COM” for common respectively.
Step 4 – Measure voltage by placing the red lead on the terminal that has the higher potential and the black lead on the terminal with lower potential or closer to the ground.
How Do You Measure Amps with a Digital Multimeter?
Step 1 – Set the function selector switch to the “A=” position.
Step 2 – Connect the black lead to the “COM” terminal and the red lead to the “300mA” terminal on the device.
Step 3 – Connect the meter in series to the device that you want to measure amperage by inserting between two points on an open circuit. The output will be displayed in milliamps.
How Do You Measure Resistance with a Digital Multimeter?
Step 1 – Disconnect all power sources and external inputs from the device that you want to measure resistance across.
Step 2 – Turn the function selector switch to the “O” position.
Step 3 – Connect the red lead to the “VO” terminal on the device and the black lead to the “COM” terminal. You should see “OL” displayed on the multimeter.
Step 4 – Connect the leads across the device or circuit that you want to measure the resistance across.
How to Test a Battery With a Digital Multimeter
Step 1 – Turn on the digital multimeter if it is in the off position and allow it to complete its self diagnostic check.
Step 2 – Move the function selector switch to measure DC voltage.
Step 3 – Connect the black probe to the “COM” port and the redo probe to the “V” port on the multimeter.
Step 4 – Place the black lead on the negative terminal or side of the battery followed by placing the red probe on the positive terminal. The multimeter will now display the DC voltage output of the battery.
Step 5 – Compare the voltage output for the battery type against the following table of ratings for alkaline batteris:
AAA – 1.5V
AA – 1.5V
C – 1.5 V
D – 1.5 V
9V – 9V
New batteries will display a slightly lower voltage output and rechargeable batteries will many times be rated from 1.25V to 1.4 V. If your batteries test significantly lower than the above values, then it could be a good indicator of needing to buy or recharge your batteries depending on what type that you own.

A capacitor is used to store energy so that it can provide power to any kind of electrical appliance when it is needed. Over time, though, the capacitor does begin to wear out and when this happens, its effectiveness in powering the appliance can diminish. Therefore, conducting a simple test on the capacitor can provide the necessary insight into whether the capacitor is worn out or if there is something else wrong with the appliance.

Testing a Capacitor
Before doing anything with the capacitor, disconnect the appliance from the electrical source. Once you’ve done this, remove it from the unit. Some high powered capacitors hold a charge even after it has been unplugged; therefore, take a screwdriver with an insulated handle and touch the metal of the tool to the metal terminals. This will, if done simultaneously, remove any power that is left in the capacitor so that it is safe to work and test.

Now that the capacitor is free of any charge, take your capacitor tester and turn it on. If it is getting power, typically a small screen will appear or a red light will turn on. This all depends on if the tester is a digital one or an analog one. You want to set the capacitor tester to the OHM scale. Most of these testers come with OHM as the standard; however, sometimes you’ll have to change it. An OHM is a measure of electrical resistance.

Taking the two leads and pressing them together zeros the meter. Once that is done, it is time to test the capacitor. Touch the red probe to the terminals of the capacitor on the left and the black probe on the right. The second you’ve made the connection, pay attention to the meter. If the needle goes away from the left, heads toward the right and then goes back to the left, the capacitor is working. If it goes to the right and doesn’t return to the left, that means the capacitor is bad or it has shorted out. Run the test two or three times to ensure that the capacitor is, in fact, screwed up.

The term wire gauge refers to a measurement of what the diameter of a wire is. This measure can then be used to determine what the electrical resistance, weight per unit of length, and the amount of current that can safely be carried by the wire. There are two internationally accepted measures for wire gauge including the Metric Wire Gauge (MWG) and American Wire Gauge (AWG) standards.
Why Does Wire Gauge Matter?
Wire gauge can be used for a number of purposes including but not limited to: carrying or transporting electrical current, connect stereo speakers to a main stereo unit, and to provide grounding wires for equipment. If the incorrect wire gauge is used, it can result in the wire overheating or melting and ultimately result in an electrical fire. As a result, building codes in all developed and many developing nations require external authorities or inspectors to verify the correct gauge of wire is used for new construction or remodeling work on structures.
How is Wire Gauge Used in U.S. Building Construction?
The minimum safety standard for wire gauge in the United States for lighting circuits is #14 gauge wire. Quality electricians, however, will choose to use #12 gauge wire when they are given the liberty to choose the gauge to install in a new or remodeled home. By using a thicker wire gauge, there is overall less resistance to the electric current and less heat loss experienced. As a result, the structure will experience a steadier power source and minimal light flicker. Another advantage to the thicker wire gauge is that 20-amp fuses may be used while the normal lighting fuses are rated at 15-amps.
How Does Wire Gauge Can Impact Circuit Breaker Panels?
By knowing about wire gauge and understanding its use, it can have secondary effects on the structural circuit breaker installed for the home or business. By installing greater than required wire gauge, excessive heat build-up will be minimized, and will preclude fuses being tripped off. Since thicker wire gauge can transport greater amount of electricity, heat build-up is precluded as is done with thinner wire gauges and fusing problems are prevented. Using the minimum required wire gauge can result in fire hazards resulting and longer-term consequences for the home.
How to Use Wire Gauges with Speaker Wire?
Many consumers, however, don’t need to worry about the wire gauge installed in their home or structure if moving into an already developed house or apartment. A common use, however, is trying to determine what type of wire gauge to use for stereo or television speaker wire. For entertainment centers, a common wire gauge used is the #12 AWG rating with some stereo users preferring to use the #10 AWG wire for the bass or subwoofer speakers.

An oscilloscope is a tool that allows the user to do two things. The first is measure time-varying signals. The way it does this is it shows details of the wave shape. The faster the wave shape, the faster the signal over a period of time. This leads to the second thing it does which is measure different aspects of time-varying signals such as the frequency of the signal and the peak value of the signal. Whenever there is an instance when the signal varies as time goes on, you’ll want to use an oscilloscope to measure the frequency and the peak value of that signal.

How to Use an Oscilloscope
The first step is obviously to plug it in. Turn the device on by pressing the on button. Depending on the device, this might be on the front or it might be on the back. Allow it to power up. Some oscilloscopes are quick to power up while others take a few seconds. It all depends on how old the device is. As newer ones are released, they boot up quicker. Once it is turned on, you can begin using it.

Apply a signal specifically to the input terminals on the oscilloscope. If nothing is appearing on the screen, make sure that you have matched the settings on the oscilloscope to the signal. For example, if what you’re testing is something worth 10,000 volts, if you set the oscilloscope to only 20 volts, nothing will appear. Therefore, it is important to set your units at something that will be easily interpreted.

Interpreting the Oscilloscope Results
The way the screen on an oscilloscope works is that it has an illuminated dot that travels across the screen at its “equator” when there is no signal applied. However, once a signal has been applied, the dot begins to go up and down like sound waves. It reaches its peak height and then goes down to its peak low and it repeats. This is the frequency. However, when the signal frequency is incredibly high, instead of the dot moving, instead a drawn out wave pattern is displayed. While this appears to be not moving, it actually is. It’s just such a fast frequency that you can’t visibly see the dot moving so, instead, you see the drawn lines. Compare the X-axis to the Y-axis to determine the frequency of the signal.