Hi all,
ive been looking at the Tate ambient power circuit (and others) and trying very hard to get my head around series cap's(coupling??) and how they function. i have red that they block dc and allow ac to pass and the picture i get in my head is a cap as a membrane (like a drum) and the ac beats transfering the "signal" to the other side while the dc is constant pressure and therefore not transfered to rest of circuit.
my questions are:
does my above thinking sound right?
how does the value of the cap effect the behaviour (fequencey?????)....filter IN or OUT ???
if the value filters frequency is there a calculator/formular
PLEASE dumb down reply alot i'm not a wiz at electronics :-[
thanks heaps
Here's a couple of nifty online calculators
Parallel caps.
http://www.csgnetwork.com/parallelcapacicalc.html (http://www.csgnetwork.com/parallelcapacicalc.html)
Series caps.
http://www.csgnetwork.com/seriescapacicalc.html (http://www.csgnetwork.com/seriescapacicalc.html)
Cap resonant frequency.
http://www.csgnetwork.com/capresonancecalc.html (http://www.csgnetwork.com/capresonancecalc.html)
Hope these help you out.
-Tal
thanks Talath that helps with the "standard" calculations i just also need to get my head around the mechanics of how the ac is allowed thru and how the cap rating may effect the frequencies. if at all ???
for example if i use a 100pf cap or a 1uf cap how wud that effect the circuit ???
the general arrangement im thinking of is antenna - cap - ground
please anyone ???
How AC is allowed through? You may consider it as a continous sequences of chargings and dischargings at the rate of the AC frequency involved.
The capacitive reactance is measured in Ohms and you can calculate it as:
XC=1/(2*pi*f*C)
pi=3.1415
f= AC frequency in Hz
C= capacitance value in Farad
Here is an online calculator for it: http://www.66pacific.com/calculators/xc_calc.aspx
In antenna coupling circuits you may consider variable capacitors as if they were (frequency dependent) variable resistors but the smaller the capacitor value, the higher their capacitive reactance, hence the smaller the AC current they can pass, at a given frequency of course.
In resonant circuits the variable caps can change the resonant frequency of the circuit: http://www.midnightscience.com/formulas-calculators.html
Normally the cap ratings voltage, loss, tolerance etc) does not affect its behaviour to AC, within the limits of course.
rgds, Gyula
thanks heaps gyulasun ;D
Quote from: telluric42 on February 01, 2010, 10:57:36 PM
thanks Talath that helps with the "standard" calculations i just also need to get my head around the mechanics of how the ac is allowed thru and how the cap rating may effect the frequencies. if at all ???
for example if i use a 100pf cap or a 1uf cap how wud that effect the circuit ???
the general arrangement im thinking of is antenna - cap - ground
please anyone ???
Yes, you can think of the capacitor as a hydraulic gas accumulator.
If you push gas into one "pole" the gas in the other pole
comes out. If you "ground" the second pole then gas
pushed into the first will push back out with a certain
pressure and keep trying pushing back out.
Capacitors are used with resistors and inductors to create time
delays, timing elements, frequency and phase delays as well
to isolate dc voltage levels in different circuits from one another. You will
have to use some mathematics to use them in that way to get
exact answers. To some extent you can look at existing like circuit
schematics to get nominal values. You want to use a limited
range of values so that efficiencies of multiple components match.
This is called the "Q" (quality) of the circuit. Look in Wikipedia under
capacitors. There are math equations for everything you want to do.
:S:MarkSCoffman
Your gonna have to wing it. May be fruitfull to start at the output desired and design tward the pick up.
Good reading but it leads to more questions then answers. Like ,based on the cap function cant you produce a bridge rectifier using them or an amp.