Zener Diode Voltage Regulator Circuit (No Load)

* zener diode subcircuit 
.subckt zener_diode 1 2
* connections:      | |
*               anode |
*               cathode
Dforward 1 2 1mA_diode
Dreverse 2 4 ideal_diode
Vz0 4 3 DC 7.3V 
Rz 1 3 10
* diode model statement
.model 1mA_diode D (Is=100pA n=1.679 )
.model ideal_diode D (Is=100pA n=0.01 )
.ends zener_diode

** Main Circuit **
* power supply
Vs 3 0 DC +20V
Vripple 1 3 sin ( 0V 5V 60Hz )
* zener diode voltage regulator circuit 
R  1 2 383
XD1 4 2 zener_diode 
Vzener 4 0 0
* simulated load condition
Iload 2 5 0A
Vload 5 0 0
** Analysis Requests **
.OP
.TRAN 0.5ms 100ms 0ms 0.5ms
** Output Requests **
.PLOT TRAN V(1) V(2)
.PROBE
.end