am asking about the zener diode Ds is it zener diode or not, design tips DT99-7 put a symbol of zener diode?!
http://www.irf.com/technical-info/designtp/dt99-7.pdf figure 2
if it is a zener diode am i using it to keep a positive voltage difference between Vb and Vs (equal to zener voltage) to prevent negative bias?
if i use a voltage supply of 120 volt for driving the motor should the reverse zener break down voltage be greater than that as if the reverse voltage be greater than the zener break down voltage a current well flow and their is now limiting resistance to limit the current that passes through the zener diode?