I understand that an NPN base-emitter junction needs a voltage drop of c. 0.6V so won't start turning on until Vbe exceeds that. Can I get the transistor to start conducting when the input voltage (i.e. between the circuit input and ground, common emitter connection) is around 3V.
I don't think I can use something like a potential divider or apply a bias voltage because the source may be of high impedance - and I guess either would have too much effect on the input. Or I may be talking nonsense. Feel free to tell me if I am!
-- James