3B Scientific Digital Counter (115 V, 50__60 Hz) - Manual (Page 5)

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2. Description
The electronic counter/timer is able to measure
time, frequencies, rates and periods as well as
counting events or pulses from a Geiger tube.
When counting events, it is possible to set certain
fixed periods of time for the count. In addition, an
arbitrary time period anywhere between 1 s and
99999 s can be programmed.
Counting can be triggered (started or stopped)
either by a signal to the input terminals or manu-
ally by means of a switch.
3. Technical data
Operating voltage: 9 – 12 V DC via plug-in
power supply
Input (9): 0.5 V – 15 V AC
Triggering edge: L/H
Input (7): 1 V – 15 V AC
Triggering edge: L/H
Display: 5-digit LED display
Geiger tube input: 500 V at 300 M•
Frequency ranges: 1 – 100 Hz, 1 – 100 kHz
Time periods: 1/10/60 s or manual
setting 1 – 99999 s
Dimensions: 250 x 100 x 160 mm
Weight: 0.9 kg approx.
4. Operation
Note:
The counter has no separate on/off switch. Power is
turned on simply by plugging in the power supply.
If there is a malfunction, disconnect the equipment
from the mains for a few seconds.
4.1 Time measurement
The measurement can be triggered by signals ap-
plied to terminals 9 and 7 or by pressing a button
manually.
• Set selector switch (15) to
Δt
AB (ms or s).
4.1.1 Manual trigger
• Press the "Start" button (3) and the timer will
start counting.
• Press the "Stop" (2) button and the timer will
stop counting.
• Press "Reset" (1) to set the timer back to zero.
4.1.2 Via signal (light barrier U11365)
• Connect one light barrier to socket A (12).
• Connect a second barrier to socket B (14).
When light barrier A triggers, the timing starts.
Timing stops upon triggering of barrier B.
4.1.3 Via signal (e.g. free-fall apparatus U8400830)
• Connect the free-fall apparatus via sockets (9),
(7) and (11). (Observe colour coding of termi-
nals).
The timer starts counting when the steel ball is
released from the free-fall apparatus and stops
automatically when the ball strikes the contact
plate at the bottom.
4.1.4 Time that a light barrier is obscured
• Connect sockets “Out Start” (8) and "In Stop" (7)
together using experiment leads.
• Connect a light barrier to socket A (12).
The period to be measured is the length of time
that a moving body takes to move through the light
beam. Its entry into the beam obscures the recep-
tor and starts the timer. When the body exits the
beam, the receptor detects the light again and the
timer is stopped.
4.2 Periods of a pendulum
• Set the selector (15) to the symbol T A .
• Apply an input signal to terminal (9) or connect
a light barrier to socket A (12).
The time to be measured is the number of milli-
seconds between successive low-to-high (L/H) edges
detected at terminal (9) or three interruptions to
the light beam detected at terminal A (12).
4.3 Counting periods
4.3.1 Fixed periods:
• Set the selector switch (15) to the desired pe-
riod (N
A 1/10/60 s).
• Apply an input signal to terminal (9) or connect
a light barrier to terminal A (12).
• Start counting by pressing the "Start" button
(3).
The equipment counts L/H edges at terminal (9),
pulses from a Geiger tube connected to terminal
(10) or interruptions to a light barrier connected to
terminal A (12).
4.3.2 Programmable time periods:
• Set the selector switch (15) to the symbol
N
A( ).
• Press the "Start" button (3) to set tens, hun-
dreds, thousands or ten thousands of seconds
(incremented by pressing the button).
• The "Stop" (2) has a similar effect but causes
the times to be decremented.