Can anyone tell me what voltage will trigger this electronic relay?
I have attached link to the spec sheet as a .pdf
http://timwalker.cc/relay.pdf
It is the item circled in red

 

Hello,

Did you read the datasheet?
The input is an IR led that has a voltage drop of about 1.25 Volts.
As it is an led you will need a current limiting resistor.

Bertus

 

I would like to use 3.2v

 

The first result on google for "LED calculator" will tell you what resistor to use.