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 Post subject: simple formulas for calculating tank circuit values?????????
PostPosted: Jun Tue 01, 2021 4:58 pm 
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Joined: Feb Thu 18, 2021 11:05 pm
Posts: 5
I give up! I do not want one of the tank circuit calculator sites. I want the site where, with the supplied formulas, I can use my little calculator and find the values needed in a jiffy .Am I the only person to find this site? I used to have all these formulas memorized, but they are completely fuzzy to me now. Maybe I saw this in an old electronics book. Can anyone help?.It seemed that the values were in picofarads and microhenrys to get the frequency in megahertz........shockedagain75.......A good site for the calculator is:"Tuned Circuits-Circuit Exchange Internationsl"


Last edited by shockedagain75 on Jun Thu 03, 2021 5:38 pm, edited 3 times in total.

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 Post subject: Re: simple formulas for calculating tank circuit values?????
PostPosted: Jun Tue 01, 2021 5:14 pm 
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Joined: May Tue 05, 2020 5:08 pm
Posts: 100
Location: Youngstown, OH
Is this what you are after ?

https://goodcalculators.com/resonant-fr ... alculator/


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 Post subject: Re: simple formulas for calculating tank circuit values?????
PostPosted: Jun Tue 01, 2021 5:14 pm 
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Joined: May Tue 30, 2006 4:46 pm
Posts: 11017
Location: Santa Rosa, CA
If you are willing to use a computer, there are many resonance calculator tools on the internet.

Here is one I use occasionally:

http://www.1728.org/resfreq.htm

Rich


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 Post subject: Re: simple formulas for calculating tank circuit values?????
PostPosted: Jun Fri 04, 2021 8:42 am 
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Joined: Jan Thu 16, 2020 12:29 am
Posts: 1613
shockedagain75 wrote:
I give up! I do not want one of the tank circuit calculator sites. I want the site where, with the supplied formulas, I can use my little calculator and find the values needed in a jiffy .Am I the only person to find this site? I used to have all these formulas memorized, but they are completely fuzzy to me now. Maybe I saw this in an old electronics book. Can anyone help?.It seemed that the values were in picofarads and microhenrys to get the frequency in megahertz........shockedagain75.......A good site for the calculator is:"Tuned Circuits-Circuit Exchange Internationsl"


The question is a little baffling in that if you know your capacitance and inductor values, you can work that out quickly on any calculator with the simple formula that the resonant frequency is = 1/2.pi(root(LC)).

But maybe what you are looking for, is the formula that gives the inductance for a coil of some particular number of turns & geometry?

In calculations it pays to keep the units in mks (meters kilogram seconds) and simply specify the units say for inductance, in Henrys and Capacitiance in Farads, so if say the inductance was 5 x 10^-3 you wouldn't have to bother calling it 5 milli-Henrys, or if the capacitance was say 17 x 10^-12 you would not bother calling it 17pF, you would just know what it was. And say if the frequency was in Hz and it was 50 x 10^6 Hz you would just recognize it at 50 MHz or 50 x 10^3 was 50 kHz etc.


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 Post subject: Re: simple formulas for calculating tank circuit values?????
PostPosted: Jun Fri 04, 2021 12:30 pm 
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Joined: Jan Thu 01, 1970 1:00 am
Posts: 11121
Location: 13 Critchley Avenue, PO Box 36, Monteith Ont, P0K 1P0
shockedagain75 wrote:
I give up! I do not want one of the tank circuit calculator sites. I want the site where, with the supplied formulas, I can use my little calculator and find the values needed in a jiffy .Am I the only person to find this site? I used to have all these formulas memorized, but they are completely fuzzy to me now. Maybe I saw this in an old electronics book. Can anyone help?.It seemed that the values were in picofarads and microhenrys to get the frequency in megahertz........shockedagain75.......A good site for the calculator is:"Tuned Circuits-Circuit Exchange Internationsl"


There used to be a book called something like "Allied Radio Data Handbook". In it were useful formulas and things like wire sizes etc. I can't find one on line right now, but I am sure they have been scanned and uploaded. They will have everything you are looking for.


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 Post subject: Re: simple formulas for calculating tank circuit values?????
PostPosted: Jun Fri 04, 2021 1:02 pm 
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Joined: Jan Thu 01, 1970 1:00 am
Posts: 11121
Location: 13 Critchley Avenue, PO Box 36, Monteith Ont, P0K 1P0
Maybe this will work :

https://worldradiohistory.com/BOOKSHELF ... k-1943.pdf


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 Post subject: Re: simple formulas for calculating tank circuit values?????
PostPosted: Jun Fri 04, 2021 3:59 pm 
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Joined: May Tue 30, 2006 4:46 pm
Posts: 11017
Location: Santa Rosa, CA
That's an old, but very useful edition. I grew up with that book as a teen. It's old because there are no miniature tubes in the Interchangeability list, but lots of the old style tubes listed.

Too lazy now to compute formulas... just too easy to find a calculator algorithm on the 'net for most anything I need.

Professor Coyle still around? Haven't used it in years.

Rich


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 Post subject: Re: simple formulas for calculating tank circuit values?????
PostPosted: Jun Fri 04, 2021 6:45 pm 
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Joined: Jun Sun 15, 2014 5:37 pm
Posts: 1485
Location: Montreal, Quebec
For formulas, I suspect the age of the book doesn't matter. Unless it's so old that it predates theformulas.

That Radio Shack book is good because it's small, and thus easy to thumb through. I got one in the seventies, and somewhere acquiredonefrom earlier. Not much difference.

The ARRL Handbook would have formulas, and again, for those age doesn't matter. Likely there afe nomographs, to avoid the math.

There was at least one book, likely more, about math for electronics. There was generally an avoidance of math, until the pocket calculator arrived, suddenly articles and new books about using them with electronics.


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 Post subject: Re: simple formulas for calculating tank circuit values?????
PostPosted: Jun Sat 05, 2021 1:19 pm 
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Joined: Jan Thu 16, 2020 12:29 am
Posts: 1613
From time to time, talk often comes up about the usefulness of Math in electronics.

The utility of it depends on what your are doing. In design work it is essential to get you as quickly as possible to the final design, with less experimental iterations . Of course you can get anywhere with cut and try alone, but it might take you a lot longer.

On the other hand, there is another way to look at the Math completely, because the Math may give you insight as to how something like a component of some kind is working, even though you are not calculating some value to use in a circuit.

Lets say someone tries to explain how a capacitor works and gives you the equation for a capacitor; Q(charge in Coulombs) = Capacitance (in Farads) x Voltage, or Q=CV.

From that you can see right away that V (or the voltage across the capacitors terminals) = Q/C. Meaning that a larger value of C can hold a larger value of charge Q without its voltage V being large. So if you put a tiny charge into a small value capacitor, it terminal voltage will be high, but a large value capacitor C can absorb,or store, a large charge, with a lower terminal voltage.

Then somebody comes along and ask what happens when you put a capacitor into an AC circuit. So you shift the equation into the time domain with a small increment of time dt and imagine a small voltage change dV and a small charge change dQ, and then you now have a new equation dQ/dt = C.dV/dt. And then you notice that dQ/dt is the rate of change of charge with time which is current I or Coulombs per second.

So now the new equation is I = C.dV/dt

This now tells you that in a circuit, with a capacitor, that the current in the wires leading to the capacitor's plates is proportional to the rate of change of voltage with time dV/dt.

Then you remember that higher frequencies must have a higher rate of change of voltage with time, so that obviously for any capacitor value C, it will present a lower impedance for higher frequencies, and that reminds you of how bypass capacitors work.

And, if you apply a sine wave voltage to the capacitor, the peak current will occur when the sine wave is most rapid, crossing zero, so this means that the voltage waveform and the current waveform , for a sine wave will be 90 degrees out of phase, with the current leading the voltage in the AC circuit with the capacitor.

It also becomes obvious how capacitors block DC when used in a coupling application into a resistor. And if you go the other way, rather than differentiating the equation for the capacitor with time, but integrating it instead, it becomes obvious how capacitors act as integrators and how if they receive amounts of charge by way of pulses, you have to add up the total charge to determine their terminal volatge.

More analysis would show the the reactance of the capacitor is 1/2.pi.f.C And from that you can see that the higher the capacitance value C and, or, the higher the applied frequency f, the lower the reactance value.

All of these ideas apply to inductors too. In that the math helps.

So the Math has conceptual value, apart from the utility of solving for a value for a circuit component. It helps a person understand how a component is working.


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 Post subject: Re: simple formulas for calculating tank circuit values?????
PostPosted: Jul Wed 28, 2021 12:54 am 
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Posts: 848
Location: Cave Springs, AR
Professor Coyle is still around.

https://crystalradio.net/professorcoyle ... ecyl.shtml

You are probably going to get some useful answers if you can sift through the guys that post just to show how smart they are.

When I was doing a lot of crystal radios and regens with a fixed L and variable C, I made a simple spreadsheet using the LC formula to show the tuning range.

If I had a xuF -yuF capacitor it would show me the frequency range for any coil I entered. A formula like used on P. Coyle above would help design the coil I needed.

It's never "simple". You are going to have to put forth some effort but I found it rewarding and worth it in the end.

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 Post subject: Re: simple formulas for calculating tank circuit values?????
PostPosted: Jul Thu 29, 2021 12:28 am 
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Posts: 19
To expand the topic slightly, I'd love to find the equations to calculate pi-net values. I've looked fairly hard and not found them. Plenty of charts and online calculators, but not the equations I can put into my own spreadsheet.

Input values would be Rsource, Rload, Frequency and Q.


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 Post subject: Re: simple formulas for calculating tank circuit values?????
PostPosted: Jul Sat 31, 2021 8:16 am 
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Joined: Jan Thu 16, 2020 12:29 am
Posts: 1613
KK6GM wrote:
To expand the topic slightly, I'd love to find the equations to calculate pi-net values. I've looked fairly hard and not found them. Plenty of charts and online calculators, but not the equations I can put into my own spreadsheet.

Input values would be Rsource, Rload, Frequency and Q.


Maybe looked "fairly hard", if so only on the net, they are probably there, somewhere.

Try ARRL Handbook, 71st edn 1994 on Chapter 2 page 2-55, top right. A lot of good books are not scanned into the net or hosted anywhere yet.

PS, if you don't want to use the formulae from the ARRL book you can always solve the problem graphically with a Smith chart which is surprisingly accurate, see page 21-24:

https://worldradiohistory.com/Archive-D ... 983-11.pdf


Also in the ARRL book, there are numerically worked examples, with the equations, for instance on page 11-11, matching a transistor collector output into a 50R load using a variation called network 3. My scanner is currently defunct, maybe someone will scan and post the pages for you.


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 Post subject: Re: simple formulas for calculating tank circuit values?????
PostPosted: Aug Wed 04, 2021 12:05 pm 
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Joined: Jan Fri 27, 2017 8:41 pm
Posts: 379
Location: Springwater, NY
KK6GM wrote:
...I'd love to find the equations to calculate pi-net values...


See R. C. Miedke W0RSL, "Pi and Pi-L Design Curves," p. 28, 29, 104 QST NOV 1955. I think the equations you're looking for are on page 104.

Additional good reading on this subject:

QST APR 1952, p. 54-55
QST SEP 1958, p. 26-27


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 Post subject: Re: simple formulas for calculating tank circuit values?????
PostPosted: Aug Wed 04, 2021 12:13 pm 
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Location: Annapolis, MD
https://www.google.com/search?rlz=1CAXG ... 00&bih=625

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"Voltage is fun to watch, but it's the CURRENT that does the work."


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 Post subject: Re: simple formulas for calculating tank circuit values?????
PostPosted: Aug Fri 06, 2021 3:51 pm 
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Joined: Mar Fri 14, 2014 1:32 am
Posts: 19
Quote:
See R. C. Miedke W0RSL, "Pi and Pi-L Design Curves," p. 28, 29, 104 QST NOV 1955. I think the equations you're looking for are on page 104.


Bingo! A million thanks for that. The numbers match perfectly with an online calculator I've been using.

I'll add this screen capture of the formulas for anybody else interested (from p. 104 as above)

Attachment:
File comment: Pi Network Formulas (R1 is R source, R2 is R load)
Pi Network Formulas Screen Shot.png
Pi Network Formulas Screen Shot.png [ 432.37 KiB | Viewed 762 times ]


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