How Can an Op Amp Circuit Control Constant Current in a Pirani Vacuum Gauge?

[Myrddin]

In a pirani vacuum gauge the pressure is determined by the rate at which heat is conducted away from a resistance wire by gas moleculs. The heat is supplied using a constant current source and the rate of heat dissipation determined by the temperature induced change in the resistance of the wire.

Draw an op amp circuit that can be used to deliver a constant current to an external fixed load resistor. Explain how it works in detail.




Have very basic knowledge of op amp circuits and this question has thrown me, any help will be appreciated. Already posted in engineering section to no avail so far!

 

[skeptic2]

Can you think of any ways to measure the the current through the external fixed resistor in a way the opamp can use?