Apparatus Drawings Project. Report Number 30A. A Versatile RC-Filtered Low-Voltage Power Supply and a Calibrated Direct-Coupled Amplifier
Robert G. Marcley · American Journal of Physics · 1962
A versatile RC-filtered power supply and a calibrated direct-coupled amplifier are described. The power supply furnishes operating power to various electronic devices developed for two large introductory laboratories. It provides about 250 V dc at its rated output of 70 mA, and 2.5 A at 6.3 V ac. The direct-coupled amplifier has 6 output ranges, from 0.5 to 150 V full scale. Its normal input resistance is 22 MΩ, with stable operation at input resistances of 125 MΩ being practical. Output is displayed on an external 100-μA meter. The method of achieving calibration accuracies of ±2% or better, using ±10% tolerance carbon resistors is described. Both instruments are stable and extremely reliable, requiring only standard commercial components and conventional tools and techniques for construction. The cost for parts is $16.26 and $22.05, respectively. The article contains full information regarding construction.