I need a schematic design with with parts details for a non-contact temperature sensor that with optional display. It must also have a control function that allows adjustable engagement of a 10-20 amp 12 volt relay (relative to the sensed temperature). This function will control down stream cooling activities.
The sensor must be minimal in size and weight, reliability is key for all components. Total parts cost to build prototype must not exceed $50 usd. Parts must be readily available. Once proof of concept moves to production complete units must be able to be produced economically in small batches of ~100 units / production run.