Frequency related calculations - plz help

O

overfl0w

New Member

• Jun 16, 2005

• #1

Hi, its been a while since last time i was working on some basic electronics and my mind has been slightly erased. I have gotten the basic frequency output calculations eg. f = RxC, which is easy enough looking from the transmitters perspective... although i can't seem to find a solution for the calculation of the recieving end... how do we determine the right values for the capacitance and resistance for the reciever to pickup the signal ?

thank you

 

S

stevez

Active Member

• Jun 16, 2005

• #2

It sounds like you are trying to determine resonant frequency - probably of an LC (Inductor Capacitor) circuit. Google on resonant frequency LC and you''l find lots of info.

 

mstechca

New Member

• Jun 16, 2005

• #3

I still think it is better that frequency of a transmitter is determined by:

f=1/(2*pi*sqr(L*C)) where L is inductance in henries, C = capacitance in farads, and f = frequency in hertz.

 

O

overfl0w

New Member

• Jun 16, 2005

• #4

what about the reciever side?

 

Nigel Goodwin

Super Moderator

Most Helpful Member

• Jun 16, 2005

• #5

overfl0w said:

what about the reciever side?

Click to expand...

It's the same formula that 'mstechca' has already given, it's the same formula for ANY tuned circuit.

The formula you gave doesn't seem relevent to anything?, it doesn't even include inductance? - and capacitance and inductance is what radio tuning is all about!.

 

O

overfl0w

New Member

• Jun 16, 2005

• #6

yeh i was only giving an example of a basic formula used in a 555 timer... thanx heaps

 

mstechca

New Member

• Jun 16, 2005

• #7

I think it makes sense if the receiver and transmitter formulas are the same provided that you use one inductor and one capacitor in parallel in both designs.

In some cases, a transmitter and a receiver are almost the same. In fact, it happened a couple of times to me where my receiver was also a short-range transmitter.

 

D.J.

New Member

• Jun 16, 2005

• #8

Hi,

If you are still having trouble calculating the frequency, try this online resonance frequency claculator.
http://www.ham-radio.com/lc.html
Very easy to use!

I use it sometimes when I get too lazy to use the formula, like the one mstechca posted

D.J.

 

David Bridgen

Member

• Jun 16, 2005

• #9

overfl0w said:

yeh i was only giving an example of a basic formula used in a 555 timer...

Click to expand...

I don't think so.

 

L

ljcox

Well-Known Member

• Jun 16, 2005

• #10

overfl0w said:

eg. f = RxC,

Click to expand...

R x C is time, not frequency.

Len