unilab H27507 Operating instructions

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H27507 Digital Stopclock NFU 618
H27749 Centisecond Timer Module
The Unilab stopclock is a versatile and distinctive piece of apparatus which has become
standard in most British school laboratories.
It is suitable for general purpose timing for up to one hour in centi-second (H27749) (1/100th of
a second) intervals.
Two buttons on the top control stopping/starting, lap times and reset. It can also be controlled
via three 4mm sockets on the front.
Date/Time Mode
The stopclock doubles as a standard digital clock.
To tell if the unit is in this mode, look at the small two digits on the right of the display.
If they are increasing once per second, the unit is in Date/Time mode.
Pushing and holding the black start stop button on the top will show the date, month and day of
the week. Releasing it shows the clock again.

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To change the date or time, the back cover must be removed. Locate the small ‘set’ button. Ensure
the stopclock is in Date/Time mode and push the set button.
The second digit on the unit will start to flash, indicating that this digit is to be altered.
After three seconds, the digit will start to increase by one per second, looping back to zero
at the end of the range.
Push the set button again to adjust the next number. Push the start stop button to confirm.
To adjust the date, push and hold the start stop button to display the calendar, and push the set
button. Adjust the relevant options in the same way as the time.
Stopclock Mode
The stopclock starts timing when the black start/stop button is pushed, not when it is
released. Similarly, if the timer is running, it will stop when the start/stop button is pushed.
To switch the unit into stopclock mode, push and hold the red reset
button for 5 seconds.
Time
Date
Order
Number
Range
Order
Number
Range
1
Seconds
0-59
1
10s of days
0-3
2
Hour
0-23
2
Days
0-9
3
10s of minutes
0-5
3
Months
0-12
4
Minutes
0-9
4
Day
Su-Sa

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Pushing the start/stop button a third time
will continue timing without resetting.
Pushing the red reset button when the timer
is stopped will zero the display.
Pushing the red reset button while the timer
is running displays the lap time, but the
timer will continue to run.
The timer can be stopped and started, but
not reset, while the lap time is displayed. To
go back to the current time, press the reset
button again. Press the reset button once
more to zero the display.
The unit can also be controlled using the 4mm sockets on the front.
The centre socket is common ground, the left socket is the reset circuit, and the right socket is
the start/stop circuit.
Connecting the reset socket to the common
ground has the same effect as pressing the red
reset button, and connecting the start/stop
socket to the common ground has the same
effect as pressing the black start/stop button.
Consider the following circuit made using push-
to-make switches:
Switches A and B are connected in parallel to the
stop start and common ground socket. Switch C
is connected to the reset socket and common
ground.
Pushing switch A will start the timer, and
switch B will stop the timer (or vice versa) and
switch C will reset the timer.
This setup can be used as a simple reaction
timer. Long leads should be used so the tester
can hide switch A and start the timer.
The subject of the test should watch the timer and push switch B to stop the timer as quickly as
they can after it starts.
C
A
B
C
B
A

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Centi-second Timer Module –H27749
This is a plug-in for the stop-clock that increases
overall functionality. It is designed to accept
input from devices such as light gates, and time
events accurately to 1/100th of a second.
On the front are three 4mm sockets, the centre
socket is common ground, and the left and right
sockets are labelled A and B respectively. Light
gates or switches can be connected to these to
control the stopclock.
The module functions in two modes, selected by
the two-position switch on the top.

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Clock controlled by input A
This is the simple mode where the starting and stopping of the stop clock is controlled by one
device. Anything plugged into socket B is ignored. In this mode, there is a debounce delay of
12 centi-seconds.
Clock Controlled by Inputs A and B
This mode is a little more complicated, as input from two devices is used to control the timer.
In this mode, the stop clock only responds to blocking of light gates (i.e. falling edges).
For example, a vehicle passes through one light gate, and then through another. The stopclock
will start timing as soon as the vehicle blocks the first light gate, and stop timing as soon as
the vehicle blocks the second light gate.

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Stop-clock battery
Centi-second timer module battery
Two AA cells should provide at least 12
months use. To replace the cells, remove
the two screws from the back plate, and
remove the exhausted cells, observing the
polarity, and insert a new one. Older
stopclocks have a single AA cell.
The module requires two SR44 silver oxide
button cells. To replace: unplug the module
from the stop-clock, remove the base,
slacken the retaining screws, replace the
cells (observing the polarity), retighten the
retaining screws and replace the base.
Light Gates –please refer to the light gate’s own instruction manual (NFU 401) for support
using this apparatus. Contact Philip Harris for a copy.
Safety advice
This advice is not a replacement for a formal risk assessment, which should be carried out
according to your school or LEA policy.
Warnings
For your safety, this product should be used in accordance with these instructions, otherwise
the protection provided may be impaired.

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Warranty, repairs and spare parts
The stopclock is guaranteed for a period of one year from the date of delivery to the customer.
This warranty does not apply to defects resulting from the action of a user such as misuse,
improper wiring, any operations outside of its specification, improper maintenance or repair,
or unauthorized modification.
Our liability is limited to repair or replacement of the product. Any failure during the warranty
period should be referred to Customer Services.
Please contact Customer Services or [e-mail] for advice
Supplier details
Philip Harris Education, 2 Gregory Street, Hyde, Cheshire SK14 4RH
Orders and Information Tel: [phone]
Fax: [phone]
Repairs Tel: [phone]
E-mail: [e-mail]
Website: www.philipharris.co.uk
© Philip Harris Education, 2002, 2014