Understanding Signals text

Ol' Geo

I had to stop reading/studying WAM 2.2 at Chap. 8 where sound was experimented. It was because of my deafness since infancy and I need an oscilloscope to "see" the sound waves. Hence, I jumped to Understanding Signals study for time being. Upon the chapter of R/C Circuits, I noticed there was some missing measurements of time constants in the Activity #1 section. Is there such an Errata sheet for the text? Need to check the sheet before I report. Also, what is the formula for the function of TC(t)? I used to know the formula but completely forgot. The curve of time constant looks logarithmical. So, I believe TC(t) is somewhat a logarithmic function.

Thank you.

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Ol' Geo
Retired Software Engineer

An oscilloscope is a window of unseen electronic world. - GM

Charlie Johnson

I don't know about TC(t), because TC does not change with time. However if you gan get a copy of "The Art of Electronics" 2nd Ed., page 24, you will find a formula for finding V(t)

kogerat

Hi George,

The genreal forumla for finding the charge on a·cap at time t is:

v_cap = V_app + (V_int - V_app) * e^(-t/(R*C)),

where v_cap = the charge on the cap at time t, V_app = the voltage applied,

V_int = the·initial voltage on the cap,·e·= the exponential function, t = time,

R = resitance, and C = capacitance. The book is using the theory that a cap

is essentially fully charged or discharged after 5 time time constants and

doesn't go into finding the charge on a cap at any point in time.

Hope that helps, Jim

Ol' Geo

Thanks, Charlie and Jim, for the input. Very helpful. indeed.

PS The text seems OK for now.

Geo