‰  NOW 40 WPM  ‰  
THE METER WILL READ OL, FOR OVERLOAD.  YOU CAN SEE THIS IF YOU TURN THE
METER TO THE OHMS BUT DO NOT CONNECT THE PROBES TO ANYTHING.  THE METER
SEES A RESISTANCE OVER THE MAXIMUM VALUE IT CAN MEASURE, SO IT DISPLAYS OL.
ONE NICE FEATURE IS THE AUTOMATIC SENSING OF POLARITY FOR VOLTAGE AND
CURRENT.  FOR EXAMPLE, IF YOU HAD A 9 V BATTERY AND CONNECTED THE COMMON OR
BLACK TERMINAL TO THE BATTERY POSITIVE AND THE RED TERMINAL TO THE BATTERY
NEGATIVE, A MINUS SIGN WOULD APPEAR IN F

USING THE DMM SAFELY  AS LONG AS YOU DO NOT PLACE YOUR FINGERS ON ANY
CIRCUIT THAT CONTAINS A HIGH ENOUGH VOLTAGE TO BE A DANGER TO YOU, THE
SAFETY HERE IS SAFETY FOR THE METER.  YOU NEED TO KNOW THE MAXIMUM METER
VOLTAGE AND CURRENT LIMITS.  IF YOU CONNECT THE METER TO MEASURE VALUES
OVER THESE LIMITS, YOU MAY JUST POP A FUSE IN THE METER, OR YOU MAY DO
TERMINAL DAMAGE, MEANING YOUVE LOST YOUR METER.  FOR MEASURING VALUES
BEYOND THE METER LIMITS, YOU CAN DESIGN AND BUILD A VOLTAGE DIVIDER OR
CURRENT SHUNT.  NEXT, SELECT THE PROPER DIAL SETTING AC OR DC.  TYPICALLY,
SELECTING AC WHEN YOU SHOULD HAVE SELECTED DC, OR DC INSTEAD OF AC, WILL
NOT DAMAGE ANYTHING, BUT THE READING WILL NOT BE CORRECT.  IF YOU ARE
MEASURING A VOLTAGE AND PLACE THE PROBES ACROSS A VOLTAGE, SELECTING ANY
OTHER METER DIAL POSITION CAN ALSO CAUSE A BLOWN FUSE OR A DEAD METER.  FOR
MEASURING VOLTAGE, THE TEST PROBES SHOULD BE CONNECTED TO THE COMMON
TERMINAL USUALLY CODED BLACK AND THE VOLTAGE TERMINAL.  FOR EXAMPLE, IN
FIGURE 2, THE VOLTAGE MEASURING TERMINAL IS COLORED RED ON THE RIGHT SIDE.
FINALLY, THE PROBES ARE CONNECTED ACROSS THE POINTS TO BE MEASURED.  IN
FIGURE 4, THEY ARE ACROSS A RESISTOR R1 THAT IS PART OF A CIRCUIT.
CURRENT, AC OR DC, IS MEASURED BY BREAKING THE CIRCUIT, AS SHOWN IN FIGURE
5.  THE TWO PROBES ARE CONNECTED IN SERIES WITH THE RESISTOR OR OTHER

DEVICE THAT YOU WANT TO MEASURE.  THIS IS A CHANCE TO ACCIDENTALLY BLOW THE
FUSE OR DAMAGE THE METER.  OFTEN WHEN CHECKING A CIRCUIT, YOU MIGHT MAKE
SEVERAL VOLTAGE AND CURRENT MEASUREMENTS, ONE AFTER ANOTHER.  THE PROBES
STAY CONNECTED TO THE RED AND BLACK TERMINALS FOR ALL THE TESTS.  IT IS
COMMON TO MEASURE A CURRENT AND THEN GO BACK TO MEASURE ANOTHER VOLTAGE.
IF YOU FORGET TO MOVE THE SECTOR SWITCH FROM CURRENT TO VOLTAGE, YOU WILL
DEFINITELY BLOW SOMETHING.  RESISTANCE IS MEASURED BY CONNECTING THE PROBES
ACROSS THE RESISTOR.  HOWEVER, YOU DO HAVE TO CUT OR UNSOLDER ONE END OF
THE RESISTOR SEE FIGURE, OR ELSE YOU WILL NOT MEASURE THE RESISTOR ALONE,
BUT THE PARALLEL COMBINATION OF THAT RESISTOR WITH WHATEVER OTHER
COMPONENTS ARE CONNECTED CROSS THE RESISTOR.  THE CONTINUITY POSITION SHOWN
IN THE LOWER RIGHT OF FIGURE 1 IS JUST A VARIANT OF THE RESISTOR
MEASUREMENT.  IF TWO POINTS ARE LINKED WITH A VERY LOW RESISTANCE
CONNECTION, THE OHMMETER CIRCUIT WILL DETECT THIS LOW RESISTANCE AND A BUZZ
OR BEEP WILL TELL YOU THE CONNECTION IS GOOD.  THE INSTRUCTION BOOK FOR THE
METER SAYS THE BUZZER WILL SOUND IF THE RESISTANCE BETWEEN THE TWO POINTS
‰  END OF 40 WPM TEXT  ‰  QST DE W1AW  ƒ