3B Scientific Control Unit for Critical Potential Tubes User Manual
3B SCIENTIFIC
®
PHYSICS
Control Unit for Critical Potential Tubes (1 15 V, 50/60 Hz)
Control Unit for Critical Potential Tubes (230 V, 50/60 Hz)
1000633 (115 V, 50/60 Hz)
1008506 (230 V, 50/60 Hz)
Instruction manual
01/14 ALF
1 Output for accelerating
voltage
2 Input for picoamp ampli-
fier
3 Terminal panel for mul-
timeter
4 Terminal panel for oscil-
loscope or data logger
5 Output voltage control
panel
1. Safety instructions
The control unit for critical potential tubes conforms to the safety stipulations for electrical
measuring, control and laboratory instruments
as specified in DIN EN 61010 part 1. It is intended for use in dry rooms suitable for the operation of electrical equipment.
Safe operation of the equipment can be assured
as long as it is used as stipulated. However,
safety cannot be guaranteed if the equipment is
used incorrectly or handled without due care
and attention.
If it may be assumed that the equipment may no
longer be operated safely (e.g. in the event of
visible damage), it must be taken out of use
immediately.
2. Description
The control unit is designed for the operation of
S-series critical potential tubes filled with helium
(1000620) or neon (1000621).
The equipment outputs a saw-tooth waveform
with a frequency of 20 Hz to be used as the
accelerating voltage at the anode of such tubes.
This voltage is galvanically isolated from the
operational earth of the device. This means that
an additional voltage supply of the user’s choice,
such as a battery, can also be connected between the anode and the collector electrode.
The initial and final voltages of the saw-tooth
generator can be adjusted continuously between
0 and 60 V. This makes it possible to observe a
specific section of the curve more accurately.
With the help of the built-in picoamp amplifier, it
1
is possible to trace the curve for the collector
current on an oscilloscope. The in-built SLOW
function allowing for a lower frequency (1/6 Hz
approx.) enables recording of this characteristic
with the aid of a slower measuring interface or
an XY plotter.
The equipment with the order number 1000633
includes a plug-in power supply for a mains voltage of 115 V (±10%), whereas the one with order
number 1008506 includes one for 230 V (±10%).
2. Controls
Output 1 is designed to supply the saw-tooth
accelerating voltage V
. The initial voltage is set
A
using knob 4 and the final voltage is set via knob
3.
To display the collector current as a function of
the accelerating voltage, the XY mode of the
oscilloscope can be used. You can record the
relevant voltages at 20 Hz by connecting the
scope to the FAST output.
The SLOW output allows values to be output at
lower frequency using a slow interface or an XY
plotter. The output is provided by means of a
built-in sampling method by pressing the SLOW
RUN button.
When the SLOW function is activated the LED
will light up in green. When it finishes, the LED
will turn back to red.
In both cases, the output for the saw-tooth voltage is taken from socket 1 (Y deflection) and the
output from the measuring amplifier is from output 2 (X deflection).
To set the desired parameters for the saw-tooth
voltage, a multimeter can be connected into
circuit. The voltage measured between socket 3
and ground (V
MIN) is smaller than the actual voltage by a
(V
A
MAX) or socket 4 and ground
A
factor of 1000.
The collector current I
(pA) is fed to the equip-
C
ment via socket 2 (BNC socket). When amplified
by the built-in picoamp amplifier, the current can
be measured via the terminals of an oscilloscope/data logger in the form of an equivalent
voltage (1 V/nA).
3. Technical data
Supply voltage: 12 V AC
Current measurement: 1 V/nA, BNC
Output voltage: 0 - 60 V/20 Hz, saw-
tooth
Measurement output: Socket 1: 0 - 1 V, pro-
portional to output voltage
Socket 2: 0 - 1 V, pro-
portional to collector
current I
C
Operating modes: FAST: measurement
output 20 Hz
SLOW: measurement
output 1/6 Hz
Dimensions: 170x105x45 mm approx.
4. Operation
• Connect the control unit to its plug-in power
supply. The socket for it is on the base of
the equipment.
2
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