One-shot IC in Pspice....???

[aviey]

Hello!
Can anyone help me..?...(PLEASE.... :'()

I need to use a 1 shot nonretriggerable ic such as 74121 in Pspice but I've found out that this device was not supported by Pspice A/D.....

Here's my project description...

For my project, I need to design a continuous wave (sinusoidal) at transducer operating frequency.  I have chosen the Wien-bridge oscillator to produce the signal and since I'm going to use the PA83 to drive my transducer, I realized that I need to gate the output from the oscillator (as reference from the PA83 datasheet).

I have been advised to use the analogue switch to do this. Currently, I have converted the oscillator output into a digital signal by using a single phase half wave rectifier which then connected to a comparator. From the comparator, the digital signal will then supplied to a 1 shot non-retriggerable IC. This signal is going to be the reference input of the analogue switch.

I haven't supplied the digital signal to the 1 shot IC yet because of this problem..
Can anyone please suggest me any other application that will meet this requirement?

Thanks ....