Hameg Instruments HM 8042 Bedienungsanleitung Seite 13

The ranges are selected via the switches (10), (13),
(16) and indicated by means of the LEDs (11), (14),
(18) above.
Curve Display
The curve family of a transistor covers an area of 8 x
8 divisions on the Oscilloscope display. As shown in
Figure 1, the top line of the display represents the
maximum value of the selected current range
(lmax,.=200/20/2MA)}, and the right edge of the 8 x 8
display grid represents the maximum value of the
selected voltage range (V,,,, =40/10/2V}). The display
is linear along both axes.
Thus if Vinex =40V and |n.=20MA is selected the
display has a horizontal resolution of 5V/Div. and a
vertical resolution of 2.5mA/Div.
With MIN selected the knob controls the base
current for the lower curve. Current for the 3 inner
curves varies proportionally with changes to the
upper and lower curves keeping equal separation
between the individual curves. When the HM
8042 is powered on, base current is set to a
minimum.
Adjustment of the Cursor Control Knob produces
changes in the base current according to Table 1.
Range Current (lx) No. of steps Current/step
1 0.3uA-100UA 127 0.8uA + 10%
2 3uA-1mA 127 8uA + 10%
3 30uA-1O0mMA 127 80uUA + 10%
Figure 2
Display of the Characteristic Curves
for Bipolar Transistors
1. Connect the component to be tested to the
appropriate input.
2. Ensure the BIP/FET switch [12] 1s in the BIP position.
3. Select NPN or PNP as appropriate with the NPN/
PNP switch [15].
4. Select the appropriate range for the maximum
current (1,5) [10],
voltage (Vina) [13],
and power (P,,3,) [16].
5 Press the DUT switch [2]. A display of 5 curves
similar to Figure 1 or 2 will be displayed on the
Oscilloscope. Some components can get very hot
while being tested. Please use caution when
handling components that have been connected
to the tester.
6. The separation of the curves is determined by the
base current(l,). The base current is adjusted by
turning the Cursor Control Knob [21]. With Cursor
Function switch [19] set to MAX, turning the
Cursor Control Knob will change the base current
for the top curve thus Increasing or decreasing the
collector current causing the upper curve on the
display to move accordingly.
Subject to change without notice
The actual base current can be read on the HM 8042
display when lp/l,is selected using the Test Parameter
Switch [6]. The switch to a higher range occurs
automatically when the Cursor Function switch ts set
to MAX and the Cursor Control Knob is turned
clockwise increasing the base current beyond the
upper limit of the range. The switch to a lower range
occurs automatically when the Cursor Function switch
is set to MIN and the Cursor Control Knob is turned
counter-clockwise decreasing the base current below
the lower limit of the range.
Display of Characteristic Curves
for Field Effect Transistors
The display of the characteristic curves for an FET Is
the same as for a Bipolar transistor with the following
exceptions:
— The BIP/FET switch must be in the FET position.
~ The separation of the curves is determined by the
gate voltage (V,.). Therefore, adjustment of the
Cursor Control Knob produces changes in the gate
voltage in the range of —10 to + 10V in 256 steps of
approximately 80mV.
M5 - 8042