This is a very simple Thevenin equivalent circuit calculator for a very simple circuit.

The user first inputs the various circuit parameters, those being:

Voltage in volts

The values of resistors 1, 2 and 4 in ohms

The value of the load resistance in ohms

The value of the current source, in amps

The calculations are based on first shorting the voltage source and then opening the current source, thus putting resistors 1 and 4 in parallel, after calculating the resulting resistance through this equation:

$R14=((1\mathrm{/}R1)+(1\mathrm{/}R4){)}^{-}1R14\; =\; ((1/R1)\; +\; (1/R4))^-1$

R14 and R2 and now in series and the result is:

$Rth=R14+R2Rth\; =\; R14\; +\; R2$ .

Using nodal analysis, the voltage is found through analyzing the currents which flow through the node directly on top of I1. As a result, the equation for Vth is:

$Vth=(R4V1+R1R4I1)\mathrm{/}(R4+R1)Vth\; =\; (R4V1\; +\; R1R4I1)/(R4\; +\; R1)$.

Finally, the current flowing through inputted load resistance is:

$Current=Vth\mathrm{/}(RL+Rth)Current\; =\; Vth/(RL\; +\; Rth)$