I need to supply a comparator in a bipolar way, which admits bipolar voltages of up to +-18V, like the LM139 (open collector). In its datasheet it says that the High Level Output Current is 1uA and the Low Level Output Current is 16mA. The idea at first was to do it with Arduino. However, the Arduino can't give negative voltage values, so I have to find another way to power the comparator. I use one 9V battery to give -9V. To regulate the voltage of the battery I have thought of using a zener diode acting as a voltage regulator, as shown in the following image. I choose the 1N750, which has a breakdown voltage of 4.7 V and a minimum operating current of 20 mA. Therefore, the necessary resistance to polarize it and drop a voltage of 4.7V on it is: R=(9V-4.7V)/20mA=215 ohms. Would this circuit be enough to get a stable power supply for the comparator or are there better alternatives?
The circuit with the zener would feed the next circuit. The BJT is at the output of the comparator while the two resistors and the diode serve to raise the voltage and prevent it from taking negative values.