This is the advanced version of the simple Curve Tracer.
It offers a current limiter, and a base/gate Driving Section.
The Device uses 3 transformers to generate 4 AC voltages and 3 DC voltages.
The 4 AC voltages are in series, and a switch selects between
0 - 20 - 40 - 60 - 80 V. This voltages is rectified and then passes a current
limiter which may be adjusted from 5 mA to 50 mA.
The design is straightforward, the main focus was on easy design. Of course,
an LM-10 would have a lower voltage drop, but the cost is 10 times higher :-(
It follows a relais to switch the polarity. (NPN or PNP).
This voltage is then applied to the collector or drain of the transistor.
This voltages also is the [HORIZONTAL DEFL.]
A shunt (R23,10Ω) in connection with an 10x amplifier (IC2a) amplifies
the voltage drop at the shunt to give a 100mV / 1mA reading. [VERTICAL DEFL.]
The 3rd transformer is used to generate an impulse to trigger the counter (74HC191)
which counts from 0 to 7.
The output of this counter forms with an
R2R-network a staircase which is amplified to 7 Vpp. (adjusted with R20).
This staircase is inverted with IC6a and another relais switches between the
polarity (NPN or PNP). In case a fet is to be analysed, a switch selects
between 0.5 V/DIV and 1.0 V/DIV.
In case a bipolar transitor is to be analysed, a voltage controlled current
source generates the drive current. This is done by IC6c,d.
The 3rd transformer also generates the supply voltages of -12V, +5V, +12V.
Measurement / Handling
The handling is almost self explanatory. In this section we will show some
measurents and how to obtain them.