December 18, 2020
Measuring the Vceo of a BJT can be done with a variable HT power supply:
Slowly increase the HT output until de current increases rapidly and
the voltage across
the transistor "dips"
Limit the current to a few milliamps.
Examples
2SC2987A
V
uA
10
1
50
5
100
10
200
20
220
22
240
24
250
25
223
449
2SC2987A
V
uA
-10
-1
-50
-5
-100
-10
-150
-15
-200
-20
-220
-22
-224
-22.4
-216
-140
The voltmeter has an input resistance of 10Mohm. This is corrected in the graphs.
The power supply used is an old tube transformer followed bij a 1N4007 diode bridge and
a 100uF/450V elco. A variac makes this a variable HT power supply.
The elco can be discharged with a 10K resistor (too large, should be a few Kohm) switched in by a push button
