The measuring instrument used to measure voltage, current and resistance values in electricity is called a multimeter. In addition, it has many functions such as short circuit control,transistor robustness control.It is also called measuring instrument and avometer in the market. With the amperemeter, the current, the voltage with the voltmeter, the resistance is measured with the ohmmeter. Multimeter is the measuring device that performs all these functions.
These multimeters are not used much today. The analog multimeter has a scale on it. It has advantages over digital measuring instruments. Voltage changes are easier to see on the scale. It'll break down quicker. Those with simple functions in price are cheaper than digital ones. It is also an indispensable measuring instrument for lovers of analogue systems.
Digital multimeter prices can be cheap or expensive.Determines the price, durability and precision of the digital multimeter manufactured by multimeter companies. Shows the measured value with numbers on the screen. You should always read their instructions before using them. It is also worth knowing that some models have external features, such as a heat sensor. Many models have insurance protection for high current and high voltage, but do not rely on it and not directly connect to values within the range you do not know.
Use of Multimeter
First, let's get to know the multimeter we're going to use. We used the multimeter DT-830D in almost all our contents in the circuitry.com. Available for around ₺20. It is also the most logical multimeter you can get to start and learn.
Sections of the Multimeter
Make sure your probes are installed correctly and check repeatedly before making any measurements.
Part 1: When measuring current, one of the probes is attached here.
Part 2: When measuring voltage, resistance, diode (short circuit), the probe is inserted here
Section 3: Common section, black probe is constantly plugged in here.
Part A: Dc We bring the latch here to measure voltage, if we do not know the potential difference of the source we will measure, you should start at the highest value.
Part B: We use resistance when measuring in ohms.
Part C: Buzzer, diode, used for short circuit measurement, stimulates by sound if the two probes are in contact with each other.
Part D: Varies from device to device, but produces a square wave signal in this multimethy.
Part E: It is used when measuring transistors, i.e. robustness testing.
Part F: Used when measuring high DC Current, works up to a maximum of 10A.
Part G: Used when measuring DC Current.
Part H: Used when measuring AC Voltage.
Section T: Used for the hFE value of the transistor. You can also use it if you can't decide whether the transistor you have is NPN or PNP.
Voltage (Potential Difference, Voltage) Measurement
Attach the black and red probes on the multimeter to the appropriate sockets of the measuring instrument. If the black probe is a red probe on the COM socket, let's attach it to the center socket. After completing the probe bindings of our measuring instrument, adjust the level of the multimeter to the voltage type we want to measure. E.g. After ac and DC choose the appropriate voltage type, we see the voltage we want to learn by touching the circuit probes in parallel. When measuring at the direct current, touch the probe uces to the part of the circuit (+) and the red probe (-) to the black probe. Inverse link, you can see a sign (-) on the value you are reading, which indicates that the probes are in opposite directions.
Let's install the black and red probes of the multimeter in the appropriate sockets of our measuring instrument. E.g. If we are going to measure up to 10 amps, let's put the red probe on the top socket, if we are going to measure up to 200 ma, let's put the red probe in the middle socket. However, if the amperage DC is the amperage dc we measure to the amperage type, bring the multimeter to level A (amperage). connect the probes of the measuring instrument to the circuit where you want to measure them. As is known, the multimeter is also serially connected to the multimeter circuit to measure the current. If we want to measure current at alternating voltage, this type of connection can be risky. For this purpose, first we cut the energy of the circuit where we want to measure the current value and connect the multimeter serially, and after the connection is completed, we give the energy of the circuit again. We may not be able to make that connection anytime. E.g. We cannot do this connection because it is risky how many amps a working engine pulls under load. For this, pens amperage meters are used on the market. In order to measure the current with the pliers amperage meter, the magnifier is pressed with a buffalo next to the measuring instrument to open the ring above the measuring instrument and the pliers amperage is passed to the phase we want to measure.
Resistance Value Measurement
Since we will measure the black probe of the multimeter to the com socket and the red probe to the resistance, if we are going to measure the multimeter up to the number of ohms in the resistance section by attaching it to the middle socket, the resistance level is adjusted and touch the probes of the measuring instrument parallel to the legs of the resistance. It is used for short circuit measurement with the buzzer mark on the diode stage above the multimeter. For example: if we want to test the robustness of one cable, touch one end of the probe to one end of the cable and the other to the other end of the cable if the buzzer sings, the cable is intact. Buzzer stage on electrical panels is widely used in board tests.
100k Ohm Resistance Measurement
SerialLy Connected Measurement of Two 100k Ohm Resistance
Parallel Connected Measurement of Two 100k Ohm Resistance
Many multimeters also do not measure capacitor value. Therefore, the multimeter is tested by the capacitor to see if the capacitor performs its function.
When voltage is applied to the capacitor, the capacitor is charged with the help of electrical charges to the capacitor. After charging (within 1-2 seconds), the load flow towards the capacitor is interrupted. According to this principle, multiple meters; it is taken to the ohmmeter level, the two ends of the measuring instrument are connected to both ends of the capacitor and the indicator is monitored.
If the value read from the indicator begins from a large value (infinite) and decreases rapidly, it is said that it acts as a capacitor if it quickly rises again to a very large (infinite) value. Otherwise, it indicates a problem with the capacitor. (In measurements, the appropriate multiplier of the ohmmeter is experimentally detected; as the capacitor's value shrinks, the multiplier of the ohmmeter should be enlarged; such as x10; x100).
When performing capacitor testing, the capacitor should not be connected to a circuit and should not be under a voltage. Since it collects load on the capacitor, the tension remains on it. For this reason, the capacitor ends are short-circuited and the collected load is discharged before performing the test. If the collected power is not discharged, dangerous situations may occur for human health and measuring instruments.
Most multimeters have functions that measure beta (hfe) gain by detecting whether the transistor is working, its type (PNP or NPN). These tests are carried out by correctly placing the transistor in the special socket (indicated by the letters c, b, e) on the multimeter. The collector tip of the transistor is placed in socket "c", the brain tip of the transistor is placed in socket "b" and the emitter tip of the transistor is placed in the "e" socket. If the multimeter does not have a transistor measurement function; transistor testing can be performed, except for gain measurement.