Multimeter nF and uF jump back and forth how the matter
The capacitance of the capacitor being measured is just near the point where it is not so convenient to identify it with either of these two different units of capacitance. In fact, that's when the multimeter, like a human being, can't make up its mind. Especially in the capacitance of the capacitor you test plus a few pF, a dozen pF of the multimeter pen distribution capacitance (including the distribution capacitance of the human body holding the multimeter pen) will just change the capacitance unit marking habits of the node, it is more likely to appear this phenomenon.
In the multimeter in the range range is too wide from 1uF-999kF (different multimeter range varies, according to the actual situation, this time to say a large number of range of general-purpose multimeter) so back to the existence of error, and in such uF.nF and F to see, uF and nF between the jump is negligible.
Take the thermometer, industrial thermometer and human body mercury thermometer, industrial thermometer in measuring hundreds of thousands of temperature 0.01-0.1 degrees of error is negligible.
Why the multimeter measurement led lights do not light up
LED also belongs to the diode, also has the characteristics of unidirectional conduction, only allows the current from the positive pole of the LED to the negative pole, so we can use the multimeter diode file to measure the LED is good or bad, the red and black pens are directional, the first step can be exchanged to measure the pens, so as not to judge the error, but the LED is not the same as the ordinary diode, it is the positive conduction voltage drop is relatively high, the positive conduction voltage drop of the LED of different colours is relatively high. LED's forward conduction voltage drop is also different, if the multimeter diode gear provides a voltage lower than the LED's forward conduction voltage drop, the LED can only be slightly bright or even not bright.
Multimeter diode measurement principle
Diode gear will provide a constant current, generally 1mA (some multimeter is 2mA), when connected to the diode, you can measure the diode PN junction voltage drop, so as to judge the diode is good or bad. Since the diode gear provides a very small current, when measuring LEDs, the brightness will be lower if the LED requires a higher current.
