Waht do you need to do, If it is faulty Proteus will not help you, I have looked in Proteus and they only do DC motors you may be able to help you.
But your not 100% clear in what you want to do
wizpic
In fact, it's a 30 years old Elna sewing machine.
It use air pressure to push a sort of multi-switch who deliver:
1) motor contact
2) motor speed
The problem was very simple: just a dead plastic round part (so pressure come out)
Since it seems impossible to have it, I decide to make a switch for motor contact and short resistors too so speed was only selectable on machine, no more on pedal (pressure pedal was changed by switch pedal).
The problem is that it worked ... for about 30mn and burned

in fact I don't know what happen exactly because I does'nt opened the machine another time to see it. Probably I can repair this but the problem will re-happen.
So I'm looking for making a new system, using the sewing machine potentiometer and pedal switch but with my components (except potentiometer).
Of course this because sewing machine prices are very very ... and because this machine is in perfect state.
Sorry if my english is poor

may be I was not very clear ...............................