connected to power line 30 with the cathode of d2 being connected with one terminal of resistor r4 and the emitter of transistor q2 the other terminal of r2 is coupled to ntc thermistor r3 which is coupled in series with r7 then to the anode of diode d3 the cathode of dc is coupled in series with capacitor c5 and resistor r10 to return line 32 resistor r6 is disposed between pin 3 of nand gate 22 and r7 r6 forms a voltage divider circuit with r7 and has a much greater resistance than r7 as is required to obtain the desired amount of hysteresis in the turn on turn off temperatures the collector of q2 is connected to one terminal of capacitor c2 resistor r5 and pin 2 of nand gate 22 capacitor c2 is coupled between the collector q2 and the anode of d3 capacitor c3 provides filtering to the emitter base of q2 while capacitor c2 provides filtering to input pin 2 of nand gate 22 other components of on off control 14 39 shown in fig4 are zener diode d1 resistors r6 and r9 39 capacitors c1 39 and c4 and motor protector 36 zener d1 has a cathode coupled to line 30 and an anode coupled to the junction of d3 and c5 zener d1 regulates the voltage across capacitor c1 39 resistor r9 39 and capacitor c4 are coupled in parallel with.