Constant-current source with unusually high internal resistance and good temperature stability
A transistor operating at 1 mA, with 10 kΩ in the emitter lead, gives a collector a.c. output resistance in the region of 10 MΩ. A 2-transistor circuit is described, having an output resistance of approximately 50 MΩ, with much improved temperature stability. A further modification gives an output resistance of about 1000 MΩ, corresponding to an ‘aiming voltage’ of 1 MV.
