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Transistor Curve Tracer

On USB, for bipolar trannies and FETs

Based on a Labs project | April 2012 | Find it here
Transistor Curve Tracer
This practical instrument can be used to measure and record the characteristic curves of NPN and PNP bipolar transistors, N- and P-channel JFETs, and N- and P-channel MOSFETs. The circuit is based on an R8C/13 microcontroller, which transfers the measurement data to a Windows application program via USB.
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Gerber file



Extra info / Update

Quick Project Specs
- R8C/13 microcontroller control module
- PC link via USB port
- User-friendly PC program with Help function (runs under Windows 2000 and XP)
- Curve data can be exported to and imported from Excel
- Checking transistor matching
- Records characteristic curves of NPN and PNP transistors, N-channel and P-channel MOSFETs, and N-channel and P-channel JFETs
- Plotted curves can be printed out or embedded in other applications



  • The circuit diagram does not show the link between pin 11 of K1 and pin 22 of the R8C/13 module. The PCB for the project is not affected.

  • In the circuit diagram (Figure 2, section a), the bussed connection between pin 22 (P3.0) of the R8C/13 module and resistor R24 is missing. This connection is however present on the circuit board, for which no modification is required.

  • In the component list, transistor T2 should be a type BC557A, not BC547A. No modification is required to the PCB or the schematic.

Component list
Controller board # 080068-2
R1 = 1kO5, SMD 0603
R2,R3 = 27O, SMD 0603
R4,R10,R11,R14-R28 = 470O, SMD 0603
R5,R6,R7 = 220kO, SMD 0603
R8,R9,R12,R29,R30,R31 = 4kO7, SMD 0603
R13 = 1kO, SMD 0603
C1,C2,C4,C8,C9,C11,C13 = 100nF, SMD 0603
C3,C12 = 22pF, SMD 0603
C5,C6 = 10pF, SMD 0603
C7,C10 =10µF 25V, SMD case A
D1 = LL4148
D2 = LED, 3mm, low-current
IC1 = PL2303X
IC2 = R5F21134FP (R8C/13)
K2 = USB-B socket
K1 = 20-way (2x10) DIL pinheader
S1 = pushbutton, 6mm, SMD
X1 = 20 MHz quartz crystal, SMD
X2 = 12 MHz quartz crystal, SMD
JP1 = 2-way SIL pinheader with jumper
F1 = 100 mA Polyfuse

Main board # 080068-1
R1-R18,R24-R33,R37,R38,R41-R45,R48,R51,R52,R53 = 10kO
R19,R20,R22 = 4kO7
R21 = 931kO
R23 = 88kO7
R34,R35 = 1O5
R36 = 100O
R39,R40,R46,R47 = 20kO
R49 = 1O 1W
R50 = 90kO9
C1,C2 = 2200µF 35V radial
C3-C6,C11,C12,C14-C17,C19-C35 = 100nF, lead pitch 2.5mm
C7-C10 = 10µF 25V radial
C13,C18 = 47nF, lead pitch 2.5mm
C36,C37 = 22nF, lead pitch 2.5mm
D1-D4,D6,D7 = 1N4148
D5,D8 = 5.6 V 500 mW zener diode
D9-D12 = LED, low-current, 3 mm
B1 = VM18, bridge rectifier 1 A / 100 V, DIP4
T1,T2 = BC547A
T3 = BD139
T4 = BD140
IC1 = 7812
IC2 = 7815
IC3 = 7915
IC4 = 7912
IC5,IC6,IC8,IC11,IC12 = TL082P
IC7,IC9 = DG441DJ
IC10, IC13 = TL081P
K1 = 20-way DIL socket
K2 = 3-way PCB terminal block, lead pitch 2.5mm
F1 = 100 mAT (slow) glass fuse, with holder
TR1 = mains transformer, secondary 2x 15V / 14VA
4 heatsinks type FK218/SA32 (21 K/W)
Microcontroller and PC Software: free download 080068-11.zip at [3].
PCBs 080068-1 and 080068-2, available from the Elektor Shop.
Controller board also with components fitted, Elektor Shop # 080068-91.
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