Advice 1: How to enable the right keyboard

Num Pad, or, as it is called, right (numeric) keypad is without a doubt very easy to use. Very often it happens that laptops containing the shortened version of the input device, buy a separate digital keyboard, which is connected via the USB interface.
How to enable the right keyboard
Instruction
1
If you have a regular full keyboard to enable Num Pad, use the press the NumLock key, which is located in the upper right corner. Usually when enabled, the operating mode will illuminate the corresponding led, if any.
2
If you need to include a detachable numeric keypad that works via USB, connect it to the correct port on the motherboard of the computer or laptop. Install the device driver if one is available. If not, use the add hardware wizard in control panel on the computer.
3
Search for new connected to the computer devices. Locate your NumPad keyboard, select install the driver from the Internet, let the wizard connect to your network and install the software. Please note that not all keyboards require for correct operation, install the driver, sometimes quite simple inclusion. Here all may depend on the model of computer and operating system, as well as the kind of the input device.
4
Turn on the device by pressing the appropriate buttons on the body, if any. If not, just hit NumLock.
5
If you want to enable the Num Pad work on a shortened keyboard, make sure that such feature is supported. Usually in this case the keys to the right of the letters and even numbers. Start this mode by simultaneously pressing Fn+NumLk. At the same time on the screen should appear the corresponding icon.
6
If you do not help none of the above, contact the service center as it's possible that your keyboard is damaged. Pre-check the correctness of connection of wires and their safety.
Note
Be careful when working with the buttons that perform the system intended.
Useful advice
Use the digital keyboard in the games.

Advice 2: How to enable led

Every year , the LEDs are increasingly used, they are actively used as lighting sources. If there is a need to connect the led to the execution of this work should follow certain rules.
How to enable led
You will need
  • - multimeter (tester);
  • - power source;
Instruction
1
To connect the led it is necessary to know its characteristics. Usually LEDs rated at 20 mA, rated voltage depends on the color of the glow. For red and yellow LEDs is 2 V (the valid range is 1.8 - 2.4 V). For white, green and blue 3 In (3 to 3.5 In). When connecting LEDs, it is important to accurately set the quiescent current to 20 mA. In this case, the led will work properly for many years.
2
Before connecting the led you should pick up a power source. So, if for white, green and blue LEDs two series-connected penlight batteries 1.5 V will give the sum of 3 V, the required voltage must not exceed a maximum value of 3.5 V. But if two batteries on the red or yellow led, it may simply burn out. That is why a responsible approach to the choice of power source, ensure that the voltage at the led is not exceeded.
3
If the voltage exceeds the required, the circuit should be included a quenching resistor. For example, you want to connect the led 2 to the power supply 9 V. 7 V. it Turns out unnecessary to extinguish them, according to the formula R=U/I you can determine that the desired resistance is equal to 7 V/0,02 A, or 350 Ohms.
4
Extinguishing the resistor generates heat, so it needs to have the necessary power. Calculate it by the formula P=U*I. Substitute the data: 7 V * 0,02 A = 0,14 W. This means that you need a resistor of about 0.2 W – better take some margin.
5
When using LEDs it is important in practice to choose the current above 20 mA. To do this, switch the tester to the circuit and check the amperage. If it is a little less than 20 mA, e.g., 17-18, leave him that way. The led will Shine a little less bright, but will last a very long time. If the amperage is much lower or higher, adjust it, changing the resistance of the additional resistor.
6
Pay attention to the polarity of led, wrong connection may damage it. The anode connects to the positive of power supply, the cathode to minus. From the cathode side of the led bulb is made of a flat area (slice). In addition, the cathode has a shorter output.
7
If you want to power the led or string of LEDs from AC power, then take care of the DC voltage. In the simplest case, the circuit can include a diode with a breakdown voltage not less than 400 V.
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