To control magnetic starter one-click a device shown in the figure.
When you press the SB1 through a resistor R1 to the control electrode of the thyristor VS1 receives a positive pulse. The thyristor VS1 open, and is included magnetic contactor KM1, who their contacts KM1.1, KM1.2, KM1.3 includes the load, and the contacts KM1.4 prepare the chain off of the thyristor.
The next time you press the SB1 voltage from the charged capacitor C2 is supplied to the thyristor VS1 in reverse polarity, it closes and disables magnetic starter. The next time you press the SB1 starter KM1 again included.
Parallel to the button SB1, you can include other buttons and control including load from other places.
Resistor R2 type sew-7,5 200 Ohm or two resistors MLT-2 430 Ohm included parallel.
The C1 capacitor 20 UF x 300, C2 - 0.1 µf x 250 V.
Author: V. F. Yakovlev, Shostka, Sumy region