add thermistor fit file

analysis/thermistors.py

@@ -0,0 +1,32 @@
+#%%
+import matplotlib.pyplot as plt
+import numpy as np
+
+Rload = 3300
+R_25 = 10000
+T_25 = 25 + 273.15 #Kelvin
+Beta = 3380
+Tmin = 0
+Tmax = 140
+
+temps = np.linspace(Tmin, Tmax, 1000)
+tempsK = temps + 273.15
+
+# https://en.wikipedia.org/wiki/Thermistor#B_or_%CE%B2_parameter_equation
+r_inf = R_25 * np.exp(-Beta/T_25)
+R_temps = r_inf * np.exp(Beta/tempsK)
+V = Rload / (Rload + R_temps)
+
+fit = np.polyfit(V, temps, 3)
+p1 = np.poly1d(fit)
+fit_temps = p1(V)
+
+#%%
+print(fit)
+
+plt.plot(V, temps, label='actual')
+plt.plot(V, fit_temps, label='fit')
+plt.xlabel('normalized voltage')
+plt.ylabel('Temp [C]')
+plt.legend(loc=0)
+plt.show()