Scott,
Let's see if I can help here.
Actually, you don't have the formula quite right. You are going to take the
reciprocal of each value as you add it, so if you connect two 100 microfarad
capacitors in series, you don't end up with 100 but 50. The formula is 1
over the value 1/100 plus 1/100 for the two 100 MF caps. Therefore, solving
you would have 1/100 plus 1/100 or .01 plus .01 which is .02 over 1 equals
50. If you were to add another 100 MF capacitor to that series, you would
end up with .03/100 which would be about 33 microfarads.
Another example (and test) of the formula is to use three capacitors, 100
microfarads, 200 microfarads and 300 microfarads, all in a circuit in
series. The
total (series) capacitance would be 1 / (1/100 (.01) + 1/200 (.005) + 1/300
(.00333)) or about 54.555 microfarads. On your calculator, you would add
the individual fractions .01 plus .005 plus .00333 which equals .0183333 and
then put the numerator 1 infront of it to show your results back in
microfarads which would be 54.555mf..
Of course, you are right, caps in parallel is just a question of adding up
their values, 100-+200+300 equals 600 microfarads.
Steve, K8SP
----- Original Message -----
From: "Carolyn Johnson" <[log in to unmask]>
To: <[log in to unmask]>
Sent: Monday, December 26, 2011 7:57 PM
Subject: Re: Question on time constants
> Hi,
>
> I know it's terrible, but I took my extra years ago, and all I basically
> did
> was remember the answers. A lot of what you learn you aren't going to use.
> Some of it you will. If you spend a lot of time learning a lot of theory,
> it
> really won't help any better with passing. As long as you somewhat
> understand what the materials are talking about. You'll take years at that
> rate. This is just my thoughts on it. You decide for yourself how you
> want
> to handle your particular situation.
>
> Carolyn Kj4vt
>
>
> --------------------------------------------------
> From: "Scott Howell" <[log in to unmask]>
> Sent: Monday, December 26, 2011 7:00 PM
> To: <[log in to unmask]>
> Subject: Question on time constants
>
>> Hi folks,
>>
>> I am studying away and hope I can call on you good folks now and then as
>> =
>> I try to understand the electronic theory. Ok, so I'll admit that math =
>> is not my strong point and I'm sure some believe that Hams should know =
>> this stuff really well and I do agree, but nevertheless I'm not going to
>> =
>> just memorize stuff. I don't think that will help me much because I do =
>> need to understand the "how" and I tend to do better.
>> So, here is my question.
>> I'm listening to the Handiham Extra Class lecture and this gent Tony is =
>> talking about measuring time constance. I get the general idea, but =
>> where I'm a little confused is with capacitance and resistance as it =
>> relates to series and parallel circuits.
>> Of course I should recall from my studies as a Tech and General, but =
>> that was a pile of years back and I did not put into practice what I =
>> learned. SHould find some breadboard and stuff to play with which =
>> probably would help a great deal.
>> In any case, if you have two capacitors in series equals half the value =
>> of one capacitor. SO, if I have this correct and you have two 100 micro =
>> farad caps you would actually have just 100 micro farad caps. In other =
>> words you add both together and then divide?
>> For parallel do you just add the two and do not divide?
>> What about resistors in series? I gather the resistors are doubled, so =
>> two one hundred KOhm resistors becomes 200KOhm?
>> Now of course if anyone has any references that I should review that =
>> would be beneficial to my understanding/recollection, please let me =
>> know. I unfortunately lost a lot of my notes when I moved and I had =
>> taken copious notes on the electrical theory and I wish I still had =
>> those.
>> If any of this made no sense at all just let me know because I probably =
>> did not do a good job of explaining things.
>>
>> 73
>> Scott/N3BYY
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