Series/parallel resistive circuit 1

.PS
include(pstricks.m4)

scale=25.4  # Scale in mm per inch

cct_init

vsp=25  # Vertical spacing
hsp=25  # Horizontal spacing


O: (0,0)  # Define the origin point for the circuit

move to O

VS: source(up_ vsp*2,V,); llabel(,v_s,); rlabel(,50\;\text{V},)
line right hsp*1.5
R1: resistor(down_ to 1/3 between Here and (Here.x,O.y)); rlabel(,R_1,); llabel(,15\;\Omega,)
{ # Push current location to the "stack"
  # This allows us to return to this point after drawing this branch
  dot(at Here)
  line right hsp
  R2: resistor(down_ to (Here.x,O.y)); rlabel(,R_2,); llabel(,30\;\Omega,)
}
# Return to the previous location on the "stack"
Rx: resistor(down_ to 1/2 between Here and (Here.x,O.y));rlabel(,R_x,)
R3: resistor(down_ to (Here.x,O.y)); rlabel(,R_3,); llabel(,10\;\Omega,)
dot(at Here)
line from R2.end to O

.PE