Why does the multimeter jump back and forth between nF and uF?
The measured capacitance of the capacitor is located near the node where it is not convenient to use these two different capacitance units for identification. In fact, at this point, a multimeter is just like a person, unable to make up their mind. Especially when the capacitance of the capacitor you are testing, plus a few pF or even a dozen pF of multimeter probe distributed capacitance (including the distributed capacitance of the human body holding the multimeter probe), will change the habit of identifying the unit of electrical capacity at the node, this phenomenon is more likely to occur.
The range of the multimeter is too wide, from 1uF to 999kF (different multimeters have different ranges, depending on the actual situation, this time we are talking about a large range universal multimeter), so there may be errors. However, in this case, the jump between uF and nF can be ignored.
Take thermometers as an example. Industrial thermometers and human mercury thermometers have negligible errors of 0.01-0.1 degrees when measuring temperatures in the hundreds or thousands.
What's wrong with the LED bulb not turning on when measuring the diode range of a digital multimeter
The working voltage of white light illumination LED beads is relatively high, usually around 3V, and there are individual differences in LED beads, some are low and some are high, with a working voltage generally between 2.6V and 3.2V.
The working principle of the diode mode of a digital multimeter is to measure the diode using a constant current source with an output of about 1mA. The no-load output voltage of the constant current source is about 2.8V ± 0.2V, which means that the maximum output voltage of the multimeter diode mode is only 2.8V ± 0.2V. When the measured conduction voltage of the LED bead exceeds the maximum output voltage of the multimeter diode mode, the LED bead will not light up.
Some LEDs are 6V, and when measured with a multimeter, they will not light up. It can improve voltage detection, and can also make or purchase finished constant current high-voltage power supplies, which can measure 1.8v-300v LED beads or strips
