version H28986 2014
Display operation
When the instrument is reset, the display may be set to say '0.000', (depending on load current
setting), if the reading goes above '9.999', the format "rolls over" to '10.00'. If the reading continues
to above '99.99', the overflow LED lights and the reading becomes '00.00'. In general only one
"rollover" or movement of the decimal point is allowed, before the overflow operates.
The meter will continue measuring the energy after an overflow but the leading digit and leading
zeros are not seen. If the reading over-
flows a second time the display shows “ - - - - “ and the
instrument stops measuring until the reset button is pressed.
Beep frequency
The sounder will beep each time the
second least significant
digit in the display changes, i.e.
second from the right, (provided the switch is on), except when a rollover has occurred in which
case the beep happens when the least significant digit changes.
Reading the external power meter
The external power meter shows a direct reading of the power being consumed in the range 0 -
10V. For example, if the digital display is reading a power dissipation of
40.00mW then f.s.d. on the external meter would represent 100mW and the reading of 4.0 will
have to be multiplied by 10 to give 40mW.
Over voltage warning
If the maximum voltage is exceeded the Over voltage LED will light. Reduce the voltage
immediately and REPEAT the experiment or there will be errors.
Over current warning
If the maximum current allowed in any range is exceeded the Over Current LED will light, the
buzzer will sound continuously and the display will show " - - - - ". Reduce the current then press
the reset button to clear the display and start measuring.
Typical applications
The following notes only outline the experiments that may be performed using the new instrument.
The experiments will be expanded in the fully revised version of these notes.
Mechanical and Electrical Energy
Apparatus:
Joulemeter/Wattmeter
Friction calorimeter with electric heater
Long cord
Thermometer 0 to 50˚C
Newtonmeter 0 to 100N Power
supply 12V a.c. or d.c.
Procedure:
Record the initial temperature of the metal cylinder. Apply a constant force, F, to rotate the
calorimeter, using the cord and newtonmeter, pulling the cord a measured distance, X. Record the
highest temperature reached. Calculate the temperature rise and the mechanical energy supplied
= F x X= W joules.
