import numpy as np
import matplotlib.pyplot as plt
import random
import math

plt.style.use('ggplot')
plt.figure(figsize=(20,10))

N=50000 # number of steps
T=0.5  # simulation time in seconds

c = 2200 * 10**(-6)
# v = 5
i= 5 * 10 ** (-3)
r = 0.08 * 10**3

t = np.empty(N)
Vc = np.empty(N)
Vi = np.empty(N)
Ic = np.empty(N)

dt=T/N;

# initial values
Vc[0]=0
Ic[0]=i
t[0]=0
Is=10**(-12)
Vi[0]=0

for k in range(0,N-1):
	t[k+1]=t[k]+dt

	#Vi[k+1]=20*np.sin(2*math.pi*50*t[k])	# sine
	Vi[k+1]=20*np.sin(2*math.pi*50*t[k])*(1+0.5*np.sin(10*t[k])) #sine with variable amplitude
	Vc[k+1]=Vc[k]-dt*Vc[k]/(r*c)+Is*dt/c*(np.exp(40*(Vi[k]-Vc[k]))-1)

	

plt.plot(t,Vc,label='Capacitor Voltage')
plt.plot(t,Vi,label='Input Voltage')



plt.xlabel('Time (s)')
plt.title('Peak detector circuit')
plt.legend()
plt.show()