Q:Electrical Engineering! Why can not directly use a multimeter to measure the power supply of the exchange of ripple?

Since you said the ripple, naturally is a slight fluctuations. Multimeter is generally used to measure the relatively large value of the parameters, to measure the ripple that can only use oscilloscopes such as precision instruments to complete. Interested in understanding the power regulator circuit section, as well as a variety of multimeter principle, the use of oscilloscope.

Q:My graduation thesis needs, as long as 40 words is enough!

With the rapid development of today's society, the application of electronic systems is becoming more and more extensive. Electronic equipment has become an indispensable part of people's daily work and life. As the heart of electronic equipment  power system to the electronic equipment to provide the necessary energy  plays a vital role. Power system Good security and reliability is an important guarantee for the normal operation of electronic equipment.

Q:Use multimeter and DC power supply should pay attention to what matters

Multimeter is worth noting that the resistance file can not be no measurement voltage, pay attention to range. DC power output can not be short-circuited

Q:BEC (UBEC) and adjustable buck regulator power supply is different

The main heat from the regulator, the real control of the motor MOS switch in fact heat is not large) because of its efficiency is not high, the natural output current can not be large, the general maximum of 1A or so

Q:DC power supply function is?

DC power function is to stabilize the DC power to stabilize the load in accordance with the required voltage, which is its function! DC power supply is the main role of the load to provide one or more groups of constant, no fluctuations, and can meet and meet the circuit or load working conditions of the DC power supply, is the DC power supply!

Q:I have a computer power supply, how to use it to change the power of other electrical appliances? 12V.5V must be. It has a lot of lines above, what color represents what the meaning? And then why is I connected to the power after the basic line basically no voltage output? Is there a thread that controls the output of the power supply?

5, PS-ON (green line): Responsible for the operating system management power switch, is a motherboard signal, and + 5VSB together referred to as soft power. Less than 1V when the power is turned on, greater than 4.5V when the power off, the realization of software switching machine, the network remote wake-up function (set wake-up time, through the keyboard boot) (and GND then short-circuit can start the power supply) 6, -5V (white line): (Negative voltage rarely used, such as SFX removed -5V) 7, -12V (blue): PG signal (Power Good, gray line, + 5V signal (+ 3.0 ~ + 6.0V)): before the system starts, the power supply (0.1 seconds to 0.5 seconds after the power is turned on to issue the signal) for internal inspection and testing, To the motherboard a signal, so the power is controlled by the power supply on the motherboard monitoring components. PG signal is very important, even if the output is normal, if there is no PG signal, the motherboard still can not work; if the PG signal timing is not right, will open the machine.

Q:Members help me to explain the role of the various components in detail. The There D5 regulator is 21V why the output is 20V, they said to reduce the UBE0.7V pressure drop. I do not understand, why should subtract UBE ah? The more detailed the higher probability of adoption. The Remember the details. The The Thank you all the teachers. The ? Mainly three-tier tube is how to complete the regulator?

This is the standard series regulator circuit, but the transistor is not regulated, it is only used as a regulator tube, used to adjust the voltage. Circuit connected, A point voltage through the resistor R1 into the regulator D5, as long as the working range, the regulator will be stable at 21V; In fact, each regulator will have errors, the specific choice of the regulator can be found on its DATASHEET this error; Output to the voltage on the C3, that is, the voltage regulator tube to reduce the VT BE junction voltage (if it is silicon tube, is about 0.7V); Obviously, the difference between the input voltage at point A and the output voltage on C3 is added between the CE poles of the transistor. Whether the output current changes or input voltage changes, the regulator will be through the regulation of the transistor BE to complete the transistor CE to withstand the voltage to adjust to achieve the purpose of stabilizing the output voltage.

Q:I would like to ask: DC power supply when the ground terminal when used? how to use?

Question 1: If the power supply is three-core, the terminal can be connected to the buried pillars above, if there is no copper pillars, vacant Question 2: I have not used two of the two. If it is connected, personally think that one can be. Specifically you can confirm whether the two terminals are directly connected, and the equipment manual recommended connection.

Q:DC power supply can directly charge the rechargeable battery?

Voltage Match No, Jack Match No! If the match can be

Q:Adjustable DC regulated power supply works

(3) filter circuit: the rectifier circuit output voltage in the majority of the AC component to be filtered, resulting in a relatively smooth DC voltage of the filter capacitor C to meet RL-C = (3 ~ 5) T / 2, or T For the input AC signal period, RL is the equivalent load resistance of the rectifier filter circuit. (4) voltage regulator circuit: the function of the regulator circuit is to stabilize the output DC voltage, does not change with the AC grid voltage and load changes. Commonly used integrated voltage regulator has a fixed three-terminal regulator and adjustable three-terminal regulator. Commonly adjustable adjustable positive pressure regulator with CW317 (LM317) series, their output voltage from 1.25V-37V adjustable, the simplest circuit external components only a fixed resistor and a potentiometer. The chip has a transition, overheating and safe working area protection, the maximum output current of 1.5A. The output voltage Uo expression: Uo = 1.25 (1 + R2 / R1) where R1 generally take 120-240 ohms, the output and the adjustment of the end of the output voltage regulator, the output voltage Uo of the expression: Uo = 1.25 (1 + R2 / R1) The differential pressure is the reference voltage of the regulator (typically 1.25V). I uploaded the principle of switching power supply and write the above design.