2) Explain the purpose of every component based on your task of having to control a high current high voltage motor with that teeny tiny photo eye…
Photo eye –
DPDT Switch –
1. Purpose of photo eye is to control the triggering of on-off motor at a certain external illumination. By having its resistance inversely proportional to the external light , when external light becomes brighter its resistance increases and hence the transistor is blocked and the motor is turned off. (if the motor were directly wired to the output of the transistor the frequency of the motor were diminished).
2. Purpose of transistor is to amplify the small variations of current through the resistor divider formed by the photo eye and R1. By having a resistance load on its collector it also amplifies its the base voltage to a voltage high enough to drive the relay.
3. Purpose of the relay is to trigger on-off the motor based on the current (or equivalent voltage) provided on its primary coil by the transistor (which amplifies the external illumination variations).
4. purpose of DPDT switch is to switch the polarity of the voltage applied to the motor and hence reversing the motor from “heat” mode to “cool” mode.