As shown in Figures 1 and 2, the most common forms are the very popular “capacitance multiplier.”įigure 1 The capacitance multiplier works by isolating the filter capacitor C1 from the load directly by the transistor current gain (beta), thereby making the capacitor value appear to be multiplied by the beta of the transistor.įigure 2 A variation of Figure 1 with an added Zener diode to improve line regulation. Over the intervening years between the first regulators and the newest low-noise varieties there have been a few discrete circuits that have cropped up to lower the noise floor of our power supplies even further. These advances have all gone a long way in helping us to design systems that meet specifications and are, small, cost effective and perhaps most importantly for those who pay our wages: they help us to stay on schedule. Although not to be forgotten are our Audiophile friends who always worry about the “sound of noise” in their systems. In data acquisition we commonly have 24-bit A/D converters which naturally demand low-noise support circuitry to be able to achieve their data sheet performance. This is especially true in RF Communications where we need low-phase-noise oscillators to be able to transmit and receive our complex digital communications. What has changed is our system’s need for lower noise. Noise has always been a constant and the LM7805 of 1972 has the same noise as the LM7805 purchased today. These venerable old regulators continued to change to match our design needs which led to low dropout varieties, improved transient response parts and now lower noise designs. As such, the reliability of everything electronic improved overnight. These modern IC’s even incorporated much improved current limiting and thermal protection. No longer were system designers required to spend their time designing the power supply section also.
#STUCK LOADING DENOISER 2 SERIES#
Then IC’s like the LM7805 series of voltage regulators changed everything. In the old days every instrument or system had a power supply board with discrete, homemade regulators on it to power the system.
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