I-V Curve: Diode A semiconductor diode is a two terminal nonlinear electronic device which conducts current predominantly in one direction. Due to it's nonlinearity a diode is one of the simplest examples of a device which does not follow Ohm's law. The simple I-V tracer built for the Ohm's law experiments [link] was tested for its ability to observe a 1N4148 diode's non-linearity (picture and scheme left) and plot its characteristic (Python code and graph below).

# Example Python code to demostrate ohm low. 

from I2Brick import *
import matplotlib.pyplot as plt
%matplotlib inline

port = I2Brick('COM4')             #Windows: Initialize serial communication with I2Bricks
#port = I2Brick('/dev/ttyUSB0')    #Linux: Initialize serial communication with I2Bricks

print(ard(port))                   #test communication between ARD and PC

R_sense=100
voltage=[]
current=[]

for v in range (0, 4000,25):
    dac(port,0, v)               #set dac voltage
    ADC0 = adc(port,0)              #read adc0 voltage
    ADC1 = adc(port,1)
    if (ADC0<0 or ADC0>4096): ADC0 = 0
    if (ADC1<0 or ADC1>4096): ADC1 = 0
    voltage.append((ADC0 - ADC1)/1000)   #calculate voltage
    current.append(ADC1/R_sense)        #calculate current


port.close()
plt.plot(voltage, current)
plt.plot(voltage, current,label='Diode: 1N4148')
plt.axis([0,0.9,0,14])
plt.title('i-v curve')
plt.legend()
plt.xlabel('Voltage [V]')
plt.ylabel('Current [mA]')
plt.show()

I2Brick Firmware 3.0. Supported brick: ARD, OLD, DAC, ADC

DCA75 Pro Advanced Semiconductor Analyser For comparison, the 1N4148 was tested with the Peak Electronics Atlas DCA75 Pro Advanced Semiconductor Analyser (right).

There are more results for the simple I2Bricks I-V curve tracer controlled by Python code below.

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