Answers are grounded in this paper and cite their sources.
A galvanometer amplifier is described embodying a high degree of negative feed-back through vacuum photocell and valve amplification. This results in high input impedance, extended frequency-response and improved stability, the noise level of the system being close to the theoretical lower-limit of Brownian movement. The amplifier is therefore suitable for the reception of small voltages from sources of relatively high internal resistance from the lowest frequencies, the upper frequency limit being dependent on the degree of feed-back and of course the particular galvanometer incorporated. The observation of biological action potentials from small nerve bundles forms an important field of application.
No takes yet. Share an insight, caveat, or question.
Frankenhaeuser et al. (1949) studied this question.
Synapse has enriched 10 related papers. Consider them for comparative context: