Soft starter and variable speed control for AC motor

Hi. I just found and built the attached schematic. It is a soft starter and a speed controller for AC motors. I checked the circuit and it worked with 70W/230V light bulb and then with a 720W angle grinder.
For making the soft starter working, I needed to make it start in the same time with the grinder, so I connected a new 3x1.5mmp cable from the grinder's switch to the circuit. Please find attached the connection schematic.
I would like to ask a few questions about this circuit:
1. Does the connection of the motor is correct ? I have 2 wires going from the switch to the stator windings, then from the stator windings 2 wires are going to the brushes. Is there any better solution for connecting the motor ?
2. Does the connection of the switch is correct (B1 on the schematic) ?
3. In order to turn off the circuit, does it needs to be disconnected from both wires (live and neutral) or it is Ok to disconnect only one of the wires ?
4. When I first opened the angle grinder's case, I found an 0.22uF/275V capacitor. I would like to know if this capacitor is still needed there ? If yes, then how can I connect it to the motor ?

Apparently it is a Universal motor, if 120v NA you only need to switch one conductor (Live), the field should remain in series with the armature, normally a simple triac or SCR following a bridge (for DC control) is all you normally need.
Max

Yes, it is a universal motor.

If I do not use the soft starter, then the motor starts suddenly when button pressed and it shakes my hand... this is why I am using this circuit...

MaxHeadRoom78 said:

Apparently it is a Universal motor, if 120v NA you only need to switch one conductor (Live), the field should remain in series with the armature, normally a simple triac or SCR following a bridge (for DC control) is all you normally need.
Max

Click to expand...

Hi MaxHeadRoom78 !

Do you have a link to such a minimalistic soft starter for 240V / 2000W ?

I don't have anything on file, but most of my projects now I try and solve using a small Picmicro, there is a SCR/Triac control app on the micro site.
Also there is the Fairchild app notes AN-3006 & AN-3003 to build off of, if needed.
Max.

MaxHeadRoom78 said:

I don't have anything on file, but most of my projects now I try and solve using a small Picmicro, there is a SCR/Triac control app on the micro site.
Also there is the Fairchild app notes AN-3006 & AN-3003 to build off of, if needed.
Max.

Click to expand...

Yuo write "there is a SCR/Triac control app on the micro site" ... where is that site ?

Do a search for Triac control for e.g. AN958 etc.
Max.