# Advice 1: How to measure capacitance with multimeter

To measure capacitance of capacitors fit almost any digital multimeter. Some of these devices can measure capacity directly, others require to resort to indirect measurement.
Instruction
1
To measure the capacitance with a multimeter that has the function to connect it to the capacitor, and then select switch the most accurate of the measurement range of capacity. If on the display there is a message about the overload, switch off the device on the coarser limit. Perform this shifting until the until statement. Read them.
2
If you use the bridge console for the capacity measurement, use the meter as a device for determining bridge balance. To the corresponding pins of the bridge, connect it through the detector with the filter capacitor and the multimeter, select DC current microammeter. Connect the capacitor to the bridge, balance last low readings, then the scale of the bridge, read the statement.
3
If a multimeter with capacitance measurement function has not, as of the bridge consoles, use the following method. Take the generator of standard signals. Install a known signal amplitude equal to several volts. Connected in series the multimeter is operating in the mode of microammeter or milliammeter AC (depending on the measurement conditions), the generator and the test capacitor. Install such a frequency that the multimeter showed current not exceeding in the former case, 200 µa, and the second 2 mA (if the frequency is too low, it will not show anything). Then we split the amplitude of the voltage, expressed in volts, the square root of two to obtain the current value. Current in amps, then divide the voltage by current and you get capacitive resistance of the capacitor expressed in ohms. Then, knowing the frequency and capacitance, calculate capacitance according to the formula:

C=1/(2πfR), where C is the capacitance in farads, π is the mathematical constant "PI", f - frequency in Hertz, R is resistance in ohms.
4
Note
Do not measure in this way the capacity of electrolytic capacitors.

Discharge the capacitor in a safe way prior to measurement.

# Advice 2: How to measure capacity

Most often, the need of measuring capacity arises from the owners of vehicles to test batteries. There are some simple steps to correctly measure their capacity.
Instruction
1
The battery is a chemical current source, in which electric current is generated by chemical reactions in the battery.
2
Thus, the principle of operation of the battery is a little different from ordinary batteries. Battery capacity is the quantity of electricity which can give a new or fully charged battery.
3
Battery capacity is measured in ampere-hours or milliampere-hours. So, if the capacity of the battery is 2000ma-HR (milliampere-hours), which means that the battery can give current of 2 thousand milliamps for 1 hour or 200 mA for 10 hours.
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To determine the capacity, the battery should first be fully charged, then discharging a given current and to track the time the battery is fully discharged. Then you need to calculate the product of current times the time that battery is dead, the obtained value will be the capacityu of the battery.
5
Similarly, a measured capacity of the battery. The meaning of the measurement of the battery capacity or battery is that you can find out the time during which the battery or battery completely discharged. The battery will require a recharge and the battery will come to full unfitness.

# Advice 3: How to check alternator with multimeter

Automobile alternator is used to supply all of the electrical devices of the vehicle after starting the engine. He must always be in good condition because of his work depends on correct charging of the battery. In addition, the generator allows you to connect to the onboard network additionally many different devices. It should regularly monitor its technical condition. To check the generator with a multimeter or on a special stand.
You will need
• - multimeter.
Instruction
1
Check the relay-regulator. It serves to maintain the optimum value of the voltage in an onboard network of the car. Relay-regulator does not allow him to rise to critical levels. Start the vehicle. Switch multimeter to "voltage measurement". Measure the power supply on-Board network. This can be done on the outputs of the generator or the battery terminal. It should be around 14-14,2 V. Press down on the accelerator. Recheck the reading. If the voltage has changed more than 0.5 V, it is a sign of improper operation of the relay controller.
2
Check the diode bridge. It consists of six diodes. Three of them are positive and three are negative. Switch multimeter in mode "sound". Now with the closure of the contacts of the tester until you hear a beep. Test in both forward and back. Ate in both cases, the audible squeak, then the diode is broken and should be replaced.
3
Check the stator of the generator. It is a metal cylinder, inside of which special way winding is stacked. To check disconnect the output of the stator from the diode bridge. Inspect the condition of the windings for mechanical damage and burning. Turn the multimeter to "measure resistance". Check the coil for breakdown. For this purpose one contact of the tester press to the body of the stator, and the second to one of the terminals of the winding. If the resistance is tend to infinity, then it is serviceable. Readings less than 50 Ohms warn about the imminent failure of the generator.
4
Check the generator rotor. It is a metal rod, which is wound with the excitation winding. At one end are the slip rings on which brushes slide. After extraction of the rotor, inspect the condition of the bearings and the rotor winding. Check the continuity of winding. Turn the multimeter to "measure resistance". Measure the value between the two slip rings. If the resistance is small, the winding is OK. More detailed testing carried out on special test walls specialized STO.
Note
Automobile generators. Characteristics and location. The electrical system of any vehicle comprises a generator main source of electricity. Along with a voltage regulator it is called a generator set. Modern vehicles are equipped with alternators. They best meet the requirements.