PHYWE Timer 2-1 Operating Instructions page 2

2 PURPOSE AND DESCRIPTION
The chronometer Timer 2-1 has a 4-digit digital display and
has been specially designed for use in student experiments
and demonstrative teacher experiments. The starting and
stopping of the built-in timer piece, as well as counting, is ef-
fected by the opening and closing of electrical circuits, across
light barriers or other TTL signal sources.
Many and various experimental requirements can be fulfilled
with the 4 different operating modes that the Timer 2-1 makes
available for track experiments, for the measurement of the
time of revolution of a turning movement, for the direct meas-
urement of the period of a full swing of a mechanical pendu-
lum and for the counting of events.
3 EXPLANATION OF THE SYMBOLS
The safety isolating transformer and safe
isolation
DIN EN 61558-2-16 of the connected pow-
er supply unit 12651-99 ensure that the
regulations for safety at schools (Richt-
linien für Sicherheit im Unterricht (RiSU)) in
line with the recommendation of the Stand-
ing Conference of the Ministers of Education and Cultural Af-
fairs of the Länder in the Federal Republic of Germany are
fulfilled.
4 FUNCTIONAL AND OPERATING ELEMENTS
The instrument is fitted in an impact-resistant plastic housing,
the single carrying handle of which can be swung down to act
as an inclining prop. Four rubber feet ensure slip-resistance
and standing stability. The instrument can be stacked with
other instruments that have the same type of housing, where-
by the rubber feet fit into pan-shaped depressions in the in-
strument housing below to provide increased security against
displacement. The inclined housing position is only permissi-
ble for the top housing in a stack. The power supply unit (arti-
cle no. 12651-99) that is standardly supplied with the instru-
ment serves to connect it to the AC-mains when it is connect-
ed to the back of the instrument via the instrument connecting
plug. All other functional and operating elements are to be
found at the front of the instrument (see Fig. 1).
1 Reset button
for resetting the display to zero and to restore readiness for
measurement prior to each new measurement.
2 Slide switch
or selection of the trigger signal edge for the input Start; posi-
tion : Start of measurement by the rising edge of a TTL-
pulse (enabling of a light barrier) or by opening the electrical
connection between the sockets of the corresponding input;
position : Start of measurement by the descending edge of
a TTL-pulse (interrupting of a light barrier) or by closing the
electrical connection between the sockets of the correspond-
ing input.
Note: Should no external trigger be connected to the Start
socket, then the slide switch should be in the position
as otherwise the instrument will not operate as expected
in all operating modes.
3 Start pair of sockets
or starting time measurement in operating modes
and ; (see section 4 for a description of the operating
modes). The signal can hereby be generated through a light
barrier or a mechanical starter by the opening or closing of an
external contact.
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in accordance with
4, 5 Connecting socket for fork light barriers
for the operation of two fork light barriers. The light barriers
are supplied with a 5 VDC operating voltage. Control input
sockets (Imp.) serve to start and/or stop a time measurement
according to the operating mode that has been selected with
switch 6. The reference terminal for each control input socket
is the socket marked "Mass". The mode of action of the con-
trol inputs is dependent on the selected operating mode (see
section 4).
6 Rotary switch
for the selection of one of the 4 available operating modes
(see section 4).
7 Digital display
for the display of times measured within the range from 0.000
to 9.999 s, or of the number of counts of events from 0 to
9999.
8 Gate LED
when this LED lights up, it shows that a time measurement
and the internal clock have been started. This function is most
helpful in indicating an inadvertent triggering of timer 2 - 1.
5 HANDLING
When the operating voltage is applied, a press on the reset
button makes the timer ready for use. The operating mode
that is most suitable for the experiment that is to be carried
out is to be selected from described in section 4. Control in-
struments must be connected to the control input of the timer
for time measurements to be started and stopped. Select the
most suitable of these from the List of Equipment. Should in-
struments that are not in the list to be connected, first check
that their control signals correspond to the TTLNorm.
An automatic repeat-lock ensures that no measured time val-
ue can be unintentionally overwritten. To regain readiness for
a new measurement, press the reset button to put back the
display. A running measurement can be stopped at any time
with the reset button.
Description of the operating modes
Rotary switch 6 allows one of the four available operating
modes to be selected. Graphic symbols on the front plate
mark the switch positions.
For all operating modes, first select the one wanted with
rotary switch 6, then press the reset button. The previous
operating mode is only brought to an end after this is
done.
5.1 Pulse counting
— Turn rotary switch 6 to the "Count" position.
— Press the reset button.
The display shows readiness for measurement with 0000.
A light barrier at the "Light Barrier 1" connection now counts
the number of shadings.
5.2 Measurement of the time period during shading
— Turn rotary switch 6 to the „
— Press the reset button.
, After the pressing of the reset button, the display shows two
decimal points which confirm readiness for measurement.
" position.
2
13607-99 / 0317