缶 the マルチメータ's ダイオード ギア 照光 ダイオード?
マルチメータ ハス a ダイオード 範囲 それ できる be 使用 to 検出 ダイオード および ターン それら オン. ただし, 点灯 アップ is not 絶対, mainly due to two reason: 1) the ダイオード ギア 電圧 of the マルチメータ is low; 2) The 動作 電圧 of the LED is 比較的 高い。
The 電圧 of the ダイオード ギア of a マルチメータ is generally around 3V, which can light up normalary 発光 diodes. When 測定 the 品質 of a diode, a red probe can be used to contact the plus electrode of the LED, and a black probe can be connected to the negative electrode of the led. if the led is on, it can be judged that the led is good. ただし, いくつか メートル 付き 低 出力 電圧 できない ライト アップ LED または 缶 のみ ライト アップ わずかに. I 持っている 使用済み a 比較的 安い マルチメーター から ユニリーバ 前, しかし それ できない ライト アップ the LED. ダイオード 範囲 is 基本的に 存在しない, which is 非常に 不便。
LED is a special type of diode with forward conduction voltage drop, and this parameter varyes greatly. The 伝導 電圧 ドロップ of 発光 ダイオード with different color varyes. 一般的に 話す, the 伝導 電圧 ドロップ of 赤 発光 ダイオード is the 最小, with a range of およそ (1.5-2) V; Green comes second, around (1.8-2.5) V; The blue color has the highest voltage drop, around (2-3.5) V. So, when measuring LEDs of different colors on the same watch, their brightness is different, generally red is the brightest and blue is the darkest. Even some colors cannot be lit.
方法 宛先 チェック 漏れ あり a デジタル マルチメータ
One pen contacts the metal coating on the power socket, and the hand touches the metal part of the other pen. The meter clearly displays a voltage value of 119V! The metal coating on the socket is indeed live. After investigation, it was found that the fixing screw of the socket broke the plastic protective layer of the live wire and came into contact with the californium core. The screw pressed against the metal coating, causing the socket to be electrified. The internal resistance of the voltage range of a digital meter is mostly lOM Ω. The connection between the human body and the ground can be equivalent to a resistor (shoe, wooden floor series resistance) in parallel with a capacitor (distributed capacitance between the human body and the ground). The voltage on the live wire is transmitted to the ground through the DC resistance of the meter, meter, meter 2, human body, wooden board, and the human body distributed capacitance in parallel. The meter displays the internal resistance of the meter at both ends, where UDY is the live wire to ground voltage, RB is the internal resistance of the voltmeter, and Z is the total resistance between the human body and the ground. Obviously, the greater the internal resistance of the meter, the higher the sensitivity of the electrical testing. It must be pointed out that the above electrical testing method requires that there must be an electric current passing through the human body in order for the meter to indicate. Undoubtedly, it should be small enough that the human body cannot sense the presence of this current. The digital multimeter has an internal resistance of lOM Ω. Even when standing barefoot on damp ground, the current flowing through the human body is only 22 when the live wire voltage is 220V μ A. Pointer type multimeter is generally not suitable for electrical testing, as the internal resistance of the voltage range of such meters is much less than lOM Ω. Therefore, the sensitivity of electrical testing is very low. Attempting to use a low voltage range to improve the sensitivity of electrical testing is incorrect, as the low voltage range usually has a small internal resistance (the internal resistance of the voltage range of a pointer multimeter is multiplied by the Ohm value per volt). The sensitivity of the indication is almost not improved, but rather
