A stable d.c. source of low voltage with low internal resistance
W. R. Beakley · Journal of Scientific Instruments · 1954
A mains-driven source of 2.6 V d.c. has been developed that, for changes in mains voltage of up to ±15% and for current drains from 5 to 9 mA, provides a voltage constant to within ±0.1%. This is achieved by using a magnetic amplifier as an impedance transformer to provide a very low output resistance from a gas-filled reference tube, type 85A2. The long-term stability is determined chiefly by the reference tube, the drift of which, after an aging period, is quoted by the manufacturers as 0.1% per 1000 h.