Basics concept of Digital Multimeter : Using clock VOM

Guidelines measured by the clock (VOM)

1) Introduction multimeter (VOM)

Multimeter (VOM) is a measuring instrument indispensable to any electronic technician, multimeter has 4 main functions of the resistor measurement, measure DC voltage, AC voltage measurement and amperage.

Advantages of the clock is fast measurements, check the types of components, see the release of the load capacitor, but this clock has limited accuracy and low impedance of about 20K / Vol due fin measured in the low flow circuit we were brownouts.

2) Guide AC voltage measurement.

Use a multimeter to measure AC

When AC voltage measurement has forwarded the scale of the elevator AC, to scale higher AC voltage to be measured one place, for example if the measured voltage AC 250V AC220V us to scale, if the lower one to scale voltage to be measured the metal alarm clock scenario, if the bar is too high, the metal for inaccurate reports.

* Note - attention:

Absolutely not to scale or scale resistance when measuring currents in ac voltage => If the wrong clock will be damaged instantly!

To mistakenly scale electric current, measured in
AC => will be broken clock

To mistake the scale resistance, measured in AC
=> Will damage the resistor in the clock

* If for scales that measure DC voltage into AC power, the clock did not notice, but the clock is not affected.

To scale measuring DC voltage AC not up metal clock
but not broken clock

3) Guidance measure DC voltage by multimeter.

When measuring DC voltage, I remember turning on the ladder scale DC, when measuring rod put red on the positive (+) source, black rod into the negative (-) source, to a higher range of voltage to be measured a hiccup. For example, if we measure the DC voltage to 110V DC 250V scale, scale case to lower the voltage to be measured => kim kim dramatic newspaper, the case for an elevator too high => needles inaccurate newspaper.

Use a multimeter to measure DC voltage

* Where to false scales:

If you're so wrong scales, measuring voltage dc but let watches the clock elevator will veer false statements, misrepresentation common values ​​greater than 2 times the actual value of the DC voltage, but the clock did not broken.

To the wrong scale when measuring DC voltage => false alarm values.

* Where to mistakenly scales

Note - Note: Absolutely no to wrong clock at current scale or scales when we measure resistor voltage direct current (DC), if mistakenly broken clock will immediately !!

Where the electric current to the wrong scale
when measuring DC voltage => broken clock!

Where to wrong scale when measuring electrical resistance
dc => broken clock will resistor inside!

4) Manual resistance and impedance measurements.

With resistor scales the multimeter can measure a lot of things.

• Measure test resistor values


• Check the common measure of a segment circuit conductors


• Check the common measure of a circuit printed circuits


• Measure check the transformer windings have not informed circuit


• Measure test load discharge of the capacitor


• Measure check capacitors have detectors, short-no.


• Check impedance measurement of an electric circuit


• Measure test diodes and transistors.

* To use this scale the clock must be mounted two sub 1.5V battery inside, to use scales or 10Kohm 1kOhm have mounted 9V battery.

4.1 - Measure the resistance:

Measure the resistance test using multimeter

To measure the resistance of our tri follow these steps:

• 
  
  Step 1: To scale the clock on the scales or, if small resistor is to scale x1 or x10 ohm ohm, if large resistor then to an elevator x1Kohm or 10Kohm. => Then tuck two philosophers probe and adjust alarm clock tops to position 0 ohm.


• 
  
  Step 2: Prepare the measure.


• 
  
  Step 3: Place the probe into the two ends of the resistor, read on scale values, measured values ​​X = index scales scales
  For example, if to scale x 100 ohm and indications that the value is 27 x 27 = 2700 = 100 ohm = 2.7 K ohm


• 
  
  Step 4: If you're too high to scale Sewing up a bit, so readers will not exact values.


• 
  
  Step 5: If you're too low to scales, needles up too much, and read nor accurate values.


• 
  
  When resistance measurement scale so that we choose metallic newspaper near the bar location between the index will give the highest accuracy.

4.2 - Use a ladder to measure the test resistor capacitor

We can use resistor ladder to check the load and magnification of capacitor failure when measuring capacitor, if we use the scale ceramic capacitor or 10K ohm ohm x1K, if the goods we use ladders converge x 1 ohm or x 10 ohm.

X 1K ohm ladder used to test ceramic capacitors

Ceramic capacitors on measurements tell us:

• 
  
  Capacitor C1 is better => needles cycling when we measure


• 
  
  Capacitor C2 detectors => needles but did not return to the old location


• 
  
  Capacitor C3 been short => clockwise to = 0 ohm and not return.

Use a ladder x 10 ohm to check convergence of

The above is the measurement test of the convergence, convergence of detectors rarely or short but mainly dry (reduced capacitance) when the magnetization to know exactly the level of focus we need to measure down compared to a new capacitor with the same capacitance.

• 
  
  Above is a comparison of two measurements of the same capacitance capacitors, capacitor C1 which is the new capacitors are capacitors C2 are old, we see a magnification load capacitors C2 capacitor C1 weaker => capacitors C2 proved dry (power reduction dung)


• 
  
  Note when measuring capacitor cycling, we need to reverse probe several times to watch the cycling.

5 - Guide to measure the current with a multimeter.

Method 1: Use the scale line

To measure the current with a multimeter, the serial clock is measured with the load consumption and attention is just smaller than the current measured values ​​of the scale allows, we follow these steps

• Step 1: Set the clock on the highest scale line.


• Step 2: Place the rod load serial clock, red for the positive rod, black rod for negative way.


• If the needle on the scales lower than the decrease


• If the needle on the needle, the dramatic increase scale, if the scale has to scale the clock highest electric current is not measured.


• Metallic alarm indicators will tell us current values.

Method 2: Using scale voltage DC

We can measure the current through the load by measuring the pressure drop across the resistor in series with the load limit line, dividing the measured voltage or current limit value will indicate the current value, this method can measure the larger current capability allows the clock and clock cumg safer.

How to read the current value and voltage when measured how?

* Read the voltage value AC and DC
When measuring DC voltage, we read on the bar indicator value DCV.A

• 
  
  If we do so then we read 250V scale on lines with the highest value is 250, similar to 10V, then read on bar ladder with the highest value is 10 cases for ladders 1000V but not yet recorded for the value of bar 1000, the value read on bar Max = 10, the value is multiplied 100 times


• 
  
  When measuring AC voltage, the read value is the same. Read on AC.10V bar, if measured on different scales, we value prorated. For example if for ladder 250V, each index of 10 bar equivalent of 25V.


• 
  
  When the current measurement reading similar values ​​when measured read voltage values