Multimeter, function and use it for measurement
Multimeter used each person dealing with electronics: multimeter can make a lot of measurements and even diagnose a fault in electron devices.
Multimeters different functionality and price, which in turn depends on the quality of manufacturing, precision measurement functionality (number of features / capabilities of the device).
Overall multimeter functions are as follows.
- measuring the magnitude of electric current;
- voltage measurement between two points of the circuit;
- measurements of electrical resistance.
- measuring the electrical resistance of the sound (sometimes light) alarm (for low resistance range: less than 50 ohms);
- test signal generation simplest form (harmonic or pulse);
- the test diodes - semiconductor diodes integrity checking and finding their "forward voltage";
- test transistors - checking semiconductor transistors;
- measurement of electrical capacitance;
- inductance measurement;
- temperature measurement using an external sensor (usually a thermocouple);
- Measuring frequency harmonic signal.
An example is popular and simple multimeter Chinese-made DT-830B.
In the digital multimeter DT-830B (larger image here) can be identified:
- LCD display;
- jacks for connecting probes;
- panel to test transistors;
- the back cover (need to replace the battery of the device, the element 9 volts).
Position switch multimeter divided into sectors:
- OFF / ON - power switch multimeter;
- DCV - measuring DC voltage (voltmeter);
- ACV - measurement of AC voltage (voltmeter);
- hFe - sector include the measurement transistor;
- 1.5v-9v - battery check;
- DCA - measurement of direct current (ammeter);
- 10A - sector ammeter to measure large values of direct current (for instructions measurements are made within a few seconds);
- Diode-sector to test diodes .;
- Ohm resistance measurement sector.
Briefly about sectors Multimeter DT-830B
Sector DCV multimeter has 5 ranges, which are measured DC voltage from 0 to 1000 volts (at high voltages necessary to work very carefully).
Typically measuring voltage is switching from large to smaller provisions (if unknown quantity measured voltage). For example, before measuring the voltage on the battery pack cell phone or car, where the maximum voltage of 12 volts or 3, put the sector to "20" volts. If you put a smaller, such as "2000" millivolts device can fail. If you put a large - instrument readings will be less accurate.
When unknown quantity measurement voltage voltmeter switch is set in the upper position "1000" is volts and metering. Roughly measure, up to one volt, it is possible to set to "1000" volts.
If you need more precision switches to the lower position, so that only the value of the measured voltage does not exceed the value of the position switch gear. Multimeter DT-830B when measuring DC voltage does not require compliance with the polarity. If the probes polarity ( "+" - red, "-" - black) is inconsistent with the measured voltage polarity, the left side of the screen appear the sign "-", and the value will match the measurements.
Sector ACV multimeter (voltage measurement AC) has 2 positions - "750" and "200" volts.
Very carefully to measure voltage 220-380 volts. The procedure for measuring and setting the switch provisions similar to those in the sector DCV.
Sector DCA multimeter - a DC milliammeter is used for measuring small currents.
Sector measuring resistance - ohmmeter - divided into position from 200 ohms to 2 megohms (2,000,000 ohms).
You can measure the resistance of 1 ohms to 2 megohms, mindful of the following:
- chinese multimeter is not exact, error example and his testimony is quite large;
- possible unexpected high sensitivity with accurate dimensions.
With the closure multimeter probes between them indicates the resistance of the circuit, which should be considered (the resistance wire to probes). Thus when measuring small resistances for the exact outcome of the result that we see on the display multimeter, you subtract the value received for the closure of probes.
For example, measure the resistance of the lamp - because the lamp has a small resistance, put in position 200 ohm probes shut each other, the device shows a 0.9 ohm and this value we subtract measurements after the required resistance to what we see on the display multimeter. For example, to get the tube 70.8 - 0.9 = 69.9 ohms.
We remember that the voltmeter shows approximate, but in the case of household appliances is enough.
The work ranges from the sector is not complicated. If your screen shows the unit left multimeter, the resistance is greater than the set switch position, and if items on the screen at the position switch multimeter 2000k, it can be ragged chain.
The emergence of other numbers indicating the presence of a resistance in the circuit.
Sector 10A multimeter - measurement of direct current (ammeter). Measurements conducted permutation probes the second slot in the slot 10 A. If you want to measure current in any electrical circuit can use an ammeter, but with great caution. The instructions to the multimeter written that do measure current for several seconds, but it is better not abuse this opportunity. There are other ways to know the approximate value of the current strength.
One position for testing diodes on a sample (a small resistance) and break (infinite resistance). Measurement principles are the same as when working with a voltmeter.
To measure transistors are nest which is designated outputs of the transistor. Checked transistors of both p - p - p and p-p-p conduction to breakdown, breakage and the greater the deviation from the standard resistance transitions.
Replacing the battery multimeter
Once you notice a glitch in the display multimeter, missing numbers or impressions do not meet the exemplary values, then it's time to replace the battery. A small Phillips screwdriver - back cover - new item 9 V.