{HEAD ~ The temperature sensor} and the passive infrared sensor are mounted on {TAIL ~ a front electrical lead side} of a vertically positioned PC board, and heat generating electrical components are mounted on an opposite, back component side of the PC board 
{ HEAD ~ The temperature sensor } and the passive infrared sensor are mounted on { TAIL ~ a front electrical lead side } of a vertically positioned PC board , and heat generating electrical components are mounted on an opposite , back component side of the PC board
HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH REL REL REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH