Digital temperature controller pcb board
There are two currents in the circuit board: alternating current and direct current. These two currents play different roles in the circuit.Their main difference is that ac circuit is a direction of the transformation, and dc is not, but for pure resistance circuit, ac, dc is no different, and in not pure resistance in the circuit, because of the existence of the capacitance and inductance, capacitance and inductance of the two kinds of circuit induction is not the same, hence the difference between ac and dc.AC power is the current coming out of the transformer on the circuit board. It passes through the diode during the current flow, and then the DC power. If there is no voltmeter on the circuit board, the general method of distinguishing between DC and AC is to see if there is a rectifier diode to judge whether there is AC in this circuit. If there is no rectifier diode, in this case there is no AC in this circuit, the circuit board is DC; the current rectifier circuit is mostly bridge rectification, if there is "full bridge" in the circuit, then in the "full bridge" The former is AC, and after the "full bridge" is DC.
The coupling effect of the capacitor is mainly responsible for transmitting and amplifying the signal of the low frequency when the circuit board generates a low frequency. In order to avoid affecting the interaction between the static operation of the front and rear two-pole boards, the capacitance is matched. On the other hand, in order to prevent excessive loss of low-frequency components in the signal, in general, we will take electrolytic capacitors with relatively large capacity. In the power circuit of the circuit board, the current in the circuit turns the AC circuit into a pulsating DC circuit. Therefore, it is necessary to connect a relatively large-capacity electrolytic capacitor after the rectifier circuit, and fully utilize the characteristics of charging and discharging. . After the capacitor is passed, the original pulsating DC voltage can be changed to a relatively stable DC voltage. In the actual situation, because we want to prevent the supply voltage of each part of the circuit board from changing due to load changes, there are usually tens to hundreds of microfarads of electrolysis at the output of the power supply and the power input of the load. capacitance. Since large-capacity electrolytic capacitors generally have a certain inductance, the high-frequency and pulse-interference signals cannot be effectively filtered out. Therefore, we need to connect a capacitor with a capacitance of 0.001--0.lpF in parallel at both ends to filter In addition to high frequency and pulse interference.
PCBA board pin refers to: the connection to the PCB board, the name of the universal connector. Generally used with the mating, line end and other connectors. With the competition in the pin header connector market, some manufacturers now reduce the cost from electroplating (imitation gold) and materials (green steel, alloy, etc.), but also reduce the use characteristics and life of the product. When changing the pin header of the PCBA board, the first thing we need to operate is to use the soldering iron to tell the soldering of the PCBA board pin. Then we need to use the soldering device to suck out the PCBA board. Through the above method, we need to use a soldering device to suck out the solder, and then use a pair of tweezers to suck out the pin from the front of the circuit board. When sucking, it must be noted that it is difficult to remove the pin when the solder is not sucked. The next step is to clean the pin holes on the PCBA board, and then we can reinstall the new pin headers.
The first thing we need to do this is that we use the instrument to verify that the voltage value of each chip's power supply pin on the board is within the normal range. We also need to test the value of the operating voltage of the point to see if the value is Within the normal range. For example, in the normal case, when the silicon triode is energized, the BE junction voltage is about 0.7V, and the CE junction voltage is about 0.3V or less. If the voltage value of the BE junction of the triode is found to be greater than 0.7V during testing (except for special triodes, such as Darlington), this may be the case when the BE junction is open.
The principle of this method is to add the signal source to the input end, and then measure the waveform of each point in turn to see if it is normal to find the fault point. Sometimes we will use a simpler method, such as holding a dice by hand, touching the input terminals of each level to see if there is any reaction at the output, which is often used in amplifier circuits such as audio and video. If there is no reaction at the previous level and there is a reaction at the next level, the problem is in the previous level and should be checked.
It means that the problem of the components of the circuit board is felt by hand. It is within the normal temperature range. Under normal circumstances, the components of the circuit board will heat up after working. If there is no heat, it means The components do not work normally, but they also heat up when they are not hot. That also means that the circuit board has a fault. In general power transistors, voltage regulator chips, etc., working below 70 degrees is completely ok. If this problem is exceeded, problems will occur.FASTPCBA Technology Co.,Ltd is a competitive China digital temperature controller pcb board OEM manufacturer, supplier and vendor, you can get quick turn digital temperature controller pcb board production prototypes and samples from our factory.