For a senior engineering class I need to design a device that, using a 5 volt source I need to deliver a 5mA current with a load that can vary from 500-100K ohms. Using transistors I know one can create a current limiting circuit, but once the resistance gets high enough (not sure how to calculate how high) then ohms law takes over. I spoke to a professor who suggested I look at op amp voltage followers which from what I gather that isolates voltage from the load, but voltage is not my current concern. A friend of mine suggested I use an inverter to make the current AC and connect a transformer, thus allowing me to generate enough voltage to handle the load's resistance and since the transistor circuit limits current to 5 volts that's not a concern. Can someone direct me? I'm in over my head and time is short. thanks in advance.