BJT MOSFET and Diode curve tracer - Page 1
Forum section: electronics / projects

author: nichrist
author_rank: Newbie
timestamp: February 10, 2021, 08:33:25 am
content: HiThe Project aim was the construction of a Bipolar Junction Transistor (BJT), MOSFET and Diode curve tracer.The device is built around the PIC 18F4553 8bit microcontroller. Through the I2C the DAC DAC6574 the four analog outputs are controlled. Two of them are used for controlling the base current and the collector voltage. At the same time four ADC inputs are used in order to measure the base voltage, base current, collector voltage and emitter voltage.Technical specificationsBase or Gate or Anode terminal pin Voltage span -8V->0->+8V with 8mV maximum resolutionBase or Anode terminal pin Current span (Range A) -2mA->0->+2mA with 0.5μA resolutionBase or Anode terminal pin Current span (Range B) -20mA->0->+20mA with 5μA resolutionCollector or Drain terminal pin Voltage span -12.5V->0->+12.5V with 25mV Voltage stepsEmitter or Source or Cathode terminal pin Current span -410mA->0->+410mA with 0.1mA resolutionBase Current and Voltage sweepDAC Channel D output produce 0-5V with ~0.48mV resolution (10bit) and through appropriate Voltage Conditioning 0-6V or 0-(-6V) are achieved.The heart of the Curver is Microchip’s PIC18F4553 an 8 bit microcontroller with USB capability, 12bit ADC and lot of others peripherals. Externally a 10 bit DAC with four analog outputs is connected to the microcontroller via I2C port.Three ports are available for connecting the semiconductor to be tested. In the case of diode only the two are used. In the case of a transistor (BJT or MOSFET) all three of them are used. The ports are:• B Base or Gate or Anode terminal pin. The produced Voltage span on this pin is -8V->0->+8V with 8mV minimum Voltage step (16, 32, 64mV are also available). The Voltage measurement resolution of this pin is 2mV. The sink or shank Current span has two ranges (Range A) -2mA->0->+2mA with 0.5μA current measurement resolution and (Range B) -20mA->0->+20mA with 5μA resolution.• E Emitter or Source or Cathode terminal pin. The maximum Voltage that can be appeared on this pin is -410mV->0->+410mV The Voltage measurement resolution of this pin is 0.1mV• C Collector or Drain terminal pin. The produced Voltage span on this pin is -12.8V->0->+12.8V with 25mV Voltage step. The Voltage measurement resolution of this pin is 3mV.Regards

author: sorin
author_rank: Frequent Contributor
timestamp: February 10, 2021, 09:05:52 pm
content: Very nice project! Thanks for sharing.I wanted from a long time doing something like this, but don't know very much about making Programs for PC.Do you have any plans to share the source code of this project?

author: nichrist
author_rank: Newbie
timestamp: February 14, 2021, 09:22:14 pm
content: HiIt is a complex project, 5 schematics and a PCB 10x10cm which I made it by sent the gerbers to a China PCB factory. I made two prototypes and left with 8 empty PCBs (order 10 PCB). The board communicates via USB with the PC run the GUI of the application (written in VC++). So there are the schematics, the VC++ code, and the firmware of the device micro controller (PIC18F4550) written in microchip XC8.Regards