Multimeter - Tips for measuring whether the crystal oscillator is starting to vibrate
How to measure whether the crystal oscillator starts to oscillate without an oscilloscope. You can use a multimeter to measure whether the voltage of the two pins of the crystal oscillator is half of the working voltage of the chip. For example, if the working voltage is 5V, it is about 2.5V. In addition, if you touch the other leg of the crystal with tweezers, the voltage changes significantly, which proves that it has started to oscillate.
Precautions for using a digital multimeter
(1) When measuring resistance with the ohm range of a multimeter, remember not to measure with power on, and the measured resistance cannot have a parallel branch.
(2) When measuring a resistance with a relatively large resistance value (such as a 10M resistance), the two test leads should be short-circuited first, and the displayed value may be 1M at this time. After each measurement, you need to subtract this value from the measurement result to get the actual resistance value. (When the resistance file is high, the error will be relatively large).
(3) The connection of the internal power supply and the red and black test leads of the analog multimeter and digital multimeter:
(4) When the measured voltage (or current) cannot be estimated in advance, it should be dialed to the highest range for a test, and then select the appropriate range according to the situation.
(5) If the highest digit of the multimeter displays the number "1" during the test, and the other digits are blanked, it proves that the meter has been overloaded, and a higher range should be selected.
(6) When measuring the current, when the input current exceeds 2A, the red test lead should be connected to the "10A" jack. Identification and detection methods of digital multimeter electronic components
, The hole is generally not equipped with a protection device, so the time to measure the high current should not exceed 10~15s, so as to avoid changing the resistance value of the manganin shunt resistor after heating, which will affect the accuracy of the reading.
(7) Avoid misoperations in operation, such as using current gear to measure voltage, resistance to measure voltage or current, and capacitance to measure charged capacitors, etc., so as not to damage the instrument.
Seriously avoid when measuring large voltage (such as 220V), connect the red test lead to the current terminal, which may burn the multimeter.
(8) The indicator will jump when the measurement is first started, and the measurement should be performed after the displayed value is stable.
(9) When measuring resistance, diodes, and checking circuit continuity, the red test lead should be connected to the V•Ω jack. At this time, the red test lead is positively charged, and the black test lead is negatively charged when connected to the COM jack, which is just the opposite of the electrical resistance of the analog meter. . When testing polarized components such as diodes, transistors, light-emitting diodes (LEDs), and electrolytic capacitors, you must pay attention to the polarity of the test leads.
