The most common maintenance situation for large LAN installations is to set up a help desk. LAN users who experience problems call the help disk. Usually a technician is dispatched if the problem can’t be resolved over the phone. Let’s take a look at some of the problems the technician may encounter when dispatched. Some preliminary checks should be made first. Ensure that the workstation is plugged into electrical power. Is it turned on? Is the CRT brightness turned down? These are obvious thing that are easily overlooked and warrant…
Read MoreTroubleshooting of Transmission Lines
Vital links of communication data flow over transmission lines daily. Phone conversations, computer data, and audio and video information all depends on the media’s ability to pass these signals wholly without any loss of quality. In this section, we will look at a problem encountered in the cabling application. Many opportunities exist today for the technician who can effectively track down and repair cabling troubles. After completing this section, you should be able to Identify popular types of cabling available for LANs and other uses. Describe crosstalk interference and give…
Read MoreFingerprint Attendance System using Arduino
The project posted here is a simple Fingerprint Attendance System using Arduino and can be very useful for any place where attendance is taken for maintaining registers like offices, schools, etc. Previously, we had posted RFID based attendance system, Arduino Fingerprint Sensor Lock, etc. The project posted here utilizes a thumb impression for taking attendance. The Fingerprint Attendance System using Arduino is based on a simple algorithm called matching algorithm and is compared with previously stored templates of fingerprints against the user’s fingerprint for authentication. Maintaining a register for attendance is…
Read MoreUltrasonic Water Level Meter
Wireless Ultrasonic Water Level Meter using ATmega328 Water level indicator is one of the most popular projects over the internet but the problem with that is, it uses metal electrodes as a result corrosion is occurring. When we pass DC in water it starts to react with the metal in presence of oxygen and corrosion is occurring. This problem is minimized by using alternating current instead of direct current but there is always the risk of electric shock which can be dangerous if is handled by a non-technical person. By…
Read MoreTroubleshooting of TV and FM Radio System
A radio communication system transmits a radio frequency signal and depends on a substantial amount of that signal being received at the receiver. Now we are going to take a closer look at that problems interference causes in TV and FM radio systems since we all can identify with these. We will also discuss some methods of Troubleshooting of TV and FM Radio System used to resolve interference problems. After completing this section, you will be able to: Identify different types of interference Describe three methods to reduce interference Troubleshoot…
Read MoreReactance Modulator Circuit Operation and Troubleshooting
The reactance is efficient and provides a large deviation. It is popular and used often in FM transmitters. Figure 1 illustrates a typical reactance modulator circuit. Refer to this figure throughout the following discussion. The circuit consist of the reactance circuit and the master oscillator. The reactance circuit operates on the master oscillator to cause its resonance frequency to shift down depending on the modulating signal being applied. The reactance circuit appears capacitive in nature to the master oscillator. In this case, the reactance looks like a variable capacitor in…
Read MoreTroubleshooting of FM transmitter
The most likely types of FM radio a technician will be called to service are an automotive mobile, a fixed base station, or a hand-held portable. Either the mobile or the fixed base station can have power outputs as high as 150 W. Some of these transmitters can be damaged if not operated into the proper load impedance, usually 50-ohm. Some contain automatic circuitry to shut the transmitter off it is not connected to a proper load. Dummy loads are made for this purpose, so make sure you have one…
Read MoreArduino Based Automatic Call Answering Machine
The project “Arduino and GSM Based Automatic Answering Machine” is designed to answer the phone call with prerecorded message when we are unable to attain call. Sometime in this busy world we might not be able to attain the phone call due to several reasons (generally when we are in bathroom or watching movie in cinema or forget mobile in home). These calls might be important i.e. call might be from office or business call which cannot be ignored. Thus, the project posted here receive the call after three rings…
Read MoreRegulated Power Supply Troubleshooting
If the system is completely dead, that is nothing happens in the system, you should immediately suspect the power supply. This is one part of any system where the average technician can often find and repair a problem. Any system is powered by battery or a transformer-rectifier supply connected to the 220-V lines. Batteries usually power portable system. A 9-V battery is most common. To check its output voltage, turn the system on (to load the battery) and measure the battery’s terminal voltage. If it is significantly below 9V, perhaps…
Read More10 Level Battery Charge Indicator Circuit
We already indicates state of battery using battery status indicator circuit and battery voltage state indicator using 741 IC, this time we indicate battery status in 10 different levels. The project “10 Level Battery Charge Indicator Circuit” is designed using comparator IC LM3914, used to indicates charge of battery in 10 different level. The project uses 10 LEDs to indicate the charge of battery in 10 level i.e. each glowing LED indicates 10% of charge in battery. Let say, if seven LEDs glow, the charge available in battery is 70%. It…
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