What's the matter with the digital multimeter's diode gear measurement and the LED lamp bead not lighting up?
Maybe many people have such doubts. When the LED lamp is connected to the power supply, it is obviously good, but why when using the diode range of the digital multimeter to measure, some light up, and some do not light up. Why?
The working voltage of LED lamp beads for white light lighting is relatively high, generally around 3V, and individual LED lamp beads are different, some are low and some are high, and the working voltage is generally between 2.6V and 3.2V.
The working principle of the diode file of the digital multimeter is to use a constant current source with an output of about 1mA to measure the diode. The no-load output voltage of the constant current source is about 2.8V±0.2V, that is, the maximum output voltage of the diode file of the multimeter is only 2.8V±0.2V , when the conduction voltage of the measured LED lamp bead is large and exceeds the maximum output voltage of the multimeter diode, the LED lamp bead will not light up.
Some leds are 6v, and when measured with a multimeter, they will not light up. It can improve the voltage detection, or you can make or buy a finished constant current high-voltage power supply, which can measure 1.8v--300v lamp beads or light strips
Maybe many people have such doubts. When the LED lamp is connected to the power supply, it is obviously good, but why when using the diode range of the digital multimeter to measure, some light up, and some do not light up. Why?
The working voltage of LED lamp beads for white light lighting is relatively high, generally around 3V, and individual LED lamp beads are different, some are low and some are high, and the working voltage is generally between 2.6V and 3.2V.
The working principle of the diode file of the digital multimeter is to use a constant current source with an output of about 1mA to measure the diode. The no-load output voltage of the constant current source is about 2.8V±0.2V, that is, the maximum output voltage of the diode file of the multimeter is only 2.8V±0.2V , when the conduction voltage of the measured LED lamp bead is large and exceeds the maximum output voltage of the multimeter diode, the LED lamp bead will not light up.
Some leds are 6v, and when measured with a multimeter, they will not light up. It can improve the voltage detection, or you can make or buy a finished constant current high-voltage power supply, which can measure 1.8v--300v lamp beads or light strips
What's the matter with the multimeter nF and uF jumping back and forth
The measured capacitance of the capacitor is just around the node where it is not so convenient to use these two different capacitance units to identify. In fact, at this time, the multimeter is just like a human being, unable to make up its mind. Especially when the capacitance of the capacitor you are testing plus the distributed capacitance of the multimeter pen of a few pF or more than ten pF (including the distributed capacitance of the human body holding the multimeter pen) will just change the node where the capacitance unit is used. , this phenomenon is more likely to occur.
The range of the multimeter is too wide from 1uF-999kF (different multimeters have different ranges, according to the actual situation, this time we are talking about a large-range universal multimeter), so there is an error, and in this way uF.nF and F , The beating between uF and nF can be ignored.
Take thermometers as an example, industrial thermometers and human mercury thermometers, the error of 0.01-0.1 degrees can be ignored when industrial thermometers measure hundreds of thousands of temperatures.
