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• ## SR Re: Optimal R-C circuit calculation with slide rule

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• Stefan, Many thanks for the info. I appreciate that the frequency range could be huge, but I suspected that your interest was the audible frequency range. You
Message 1 of 18 , Aug 1, 2011
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Stefan,
Many thanks for the info. I appreciate that the frequency range could be huge, but I suspected that your interest was the audible frequency range. You have confirmed that. It also seemed likely to me that you would not combine a very high value resistor with a very low value capacitor, or vice versa, even though the product would satisfy the equation. I suppose that in summary I was trying to find out how you usually applied the equation in everyday use. Your answer satisifes my curiosity!

My thanks again, Peter Johnson

--- In sliderule@yahoogroups.com, Stefan Vorkoetter <stefan@...> wrote:
>
> Hi Peter:
>
> The range of frequencies is potential huge. I usually work in the audio frequency range (20Hz to 20kHz), but concepts apply at any frequency (although when you get into the GHz range, other factors become hugely significant).
>
> The range of component values of course depends on the frequency range. I generally use capacitors in 100pF to 10uF range (i.e. 10^-10 to 10^-5 Farads). Resistors are typically in the 1kOhm to 1MOhm range. The choice of values often depends on other factors, such as the desired input impedance.
>
> Stefan
>
> dieswartdose wrote:
> > Stefan,
> > I am quietly studying slide rule design at the present, and your problem
> > interests me. I can imagine that in times gone by some component
> > manufacturer might well have supplied a specialist slide rule to do
> > this calculation. In part the feasibility of such a rule depends on the
> > range of values of the variables. What range of frequency, resistance
> > and capacitance values do you normally encounter? Although in theory
> > there is an infinite number of resistance and capacitance combinations
> > for any given frequency, in practice you must have maximum and minimum
> > values determined by cost, size, availability, etc.
> >
> > Peter Johnson
>
> --
> Stefan Vorkoetter
> http://www.stefanv.com
>
• Cyril, Thank you for the reply. I had been thinking about a circular rule, but that is as far as it had gone. I wasn t aware that Concise had beaten me to it!
Message 1 of 18 , Aug 1, 2011
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Cyril,
Thank you for the reply. I had been thinking about a circular rule, but that is as far as it had gone. I wasn't aware that Concise had beaten me to it!
I'm sure that my old English master would not criticise my use of "literally" if I was to write that I was literally about to re-invent the wheel.
Regards, Peter Johnson

--- In sliderule@yahoogroups.com, Cyril Catt <ccatt10@...> wrote:
>
> Peter Johnson wrote: ...What range of frequency, resistance and capacitance values do you normally encounter?
>
> Peter, The Concise Model 380 Radio Computer covered ranges from 1p to 1000m on the L and C scales, and from 1 to a million on the F scale, or 12 decades on each. However, as it is circular, its scales can presumably be used for larger or smaller quantities if necessary.
>
> Cyril Catt
>
• Peter Johnson wrote: ...I had been thinking about a circular rule, but that is as far as it had gone. … Sorry Peter, I beat you to it. Having been annoyed at
Message 1 of 18 , Aug 1, 2011
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Peter Johnson wrote: ...I had been thinking about a circular rule, but that is as far as it had gone. …

Sorry Peter, I beat you to it. Having been annoyed at finding that the results on my linear rule were so often to be found off scale, I thought of a circular rule in 1952, only to be deflated by a maths master who told me I had been beaten to it - by Oughtred, about 1620.

Cyril Catt
• Nothing new under the Sun, they say! As a schoolboy, I too coveted a circular slide rule for the same reason. Some 50-odd years later my wish came true when I
Message 1 of 18 , Aug 1, 2011
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Nothing new under the Sun, they say!
As a schoolboy, I too coveted a circular slide rule for the same reason. Some 50-odd years later my wish came true when I bought a Concise 300. It has been something of a disappointment - I just can't move the inner disc as precisely as I can a conventional slide. Some thumb pressure is need to grip the disc, which presses the disc onto the body, so more force is needed to move it, which means more thumb pressure... I've not had the opportunity to try other makes. I have thought of putting the merest trace of silicone grease under the disc, but that might attack the plastic in the long term.

Peter Johnson

--- In sliderule@yahoogroups.com, Cyril Catt <ccatt10@...> wrote:
>
> Peter Johnson wrote: ...I had been thinking about a circular rule, but that is as far as it had gone.
>
> Sorry Peter, I beat you to it. Having been annoyed at finding that the results on my linear rule were so often to be found off scale, I thought of a circular rule in 1952, only to be deflated by a maths master who told me I had been beaten to it - by Oughtred, about 1620.
>
> Cyril Catt
>
• I ve used a little talcum powder in my circular rules with success. Maynard Wright
Message 1 of 18 , Aug 1, 2011
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I've used a little talcum powder in my circular rules with success.

Maynard Wright

On Monday 01 August 2011 14:09:47 dieswartdose wrote:
> Nothing new under the Sun, they say!
> As a schoolboy, I too coveted a circular slide rule for the same reason.
> Some 50-odd years later my wish came true when I bought a Concise 300. It
> has been something of a disappointment - I just can't move the inner disc
> as precisely as I can a conventional slide. Some thumb pressure is need to
> grip the disc, which presses the disc onto the body, so more force is
> needed to move it, which means more thumb pressure... I've not had the
> opportunity to try other makes. I have thought of putting the merest trace
> of silicone grease under the disc, but that might attack the plastic in the
> long term.
>
> Peter Johnson
>
> --- In sliderule@yahoogroups.com, Cyril Catt <ccatt10@...> wrote:
> > Peter Johnson wrote: ...I had been thinking about a circular rule, but
> > that is as far as it had gone.
> >
> > Sorry Peter, I beat you to it. Having been annoyed at finding that the
> > results on my linear rule were so often to be found off scale, I thought
> > of a circular rule in 1952, only to be deflated by a maths master who
> > told me I had been beaten to it - by Oughtred, about 1620.
> >
> > Cyril Catt
>
> ------------------------------------
• Maynard, Thank you for that tip - I ll give it a try. Regards, Peter Johnson
Message 1 of 18 , Aug 2, 2011
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Maynard,

Thank you for that tip - I'll give it a try.

Regards, Peter Johnson

--- In sliderule@yahoogroups.com, Maynard Wright <m-wright@...> wrote:
>
> I've used a little talcum powder in my circular rules with success.
>
> Maynard Wright
>
>
>
> On Monday 01 August 2011 14:09:47 dieswartdose wrote:
> > Nothing new under the Sun, they say!
> > As a schoolboy, I too coveted a circular slide rule for the same reason.
> > Some 50-odd years later my wish came true when I bought a Concise 300. It
> > has been something of a disappointment - I just can't move the inner disc
> > as precisely as I can a conventional slide. Some thumb pressure is need to
> > grip the disc, which presses the disc onto the body, so more force is
> > needed to move it, which means more thumb pressure... I've not had the
> > opportunity to try other makes. I have thought of putting the merest trace
> > of silicone grease under the disc, but that might attack the plastic in the
> > long term.
> >
> > Peter Johnson
> >
> > --- In sliderule@yahoogroups.com, Cyril Catt <ccatt10@> wrote:
> > > Peter Johnson wrote: ...I had been thinking about a circular rule, but
> > > that is as far as it had gone.
> > >
> > > Sorry Peter, I beat you to it. Having been annoyed at finding that the
> > > results on my linear rule were so often to be found off scale, I thought
> > > of a circular rule in 1952, only to be deflated by a maths master who
> > > told me I had been beaten to it - by Oughtred, about 1620.
> > >
> > > Cyril Catt
> >
> > ------------------------------------
>
• Many of these questions are addressed (without reference to slide rules) in the Active Filter Cookbook by Don Lancaster. It s worth a read, especially because
Message 1 of 18 , Aug 2, 2011
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Many of these questions are addressed (without reference to slide rules) in
the Active Filter Cookbook by Don Lancaster. It's worth a read, especially
because of the way he approaches transforms and scaling.

ray.

On Mon, Aug 1, 2011 at 4:07 AM, dieswartdose <dieswartdose@...> wrote:

> **
>
>
>
>
> Stefan,
> Many thanks for the info. I appreciate that the frequency range could be
> huge, but I suspected that your interest was the audible frequency range.
> You have confirmed that. It also seemed likely to me that you would not
> combine a very high value resistor with a very low value capacitor, or vice
> versa, even though the product would satisfy the equation. I suppose that in
> summary I was trying to find out how you usually applied the equation in
>
> My thanks again, Peter Johnson
>
>
> --- In sliderule@yahoogroups.com, Stefan Vorkoetter <stefan@...> wrote:
> >
> > Hi Peter:
> >
> > The range of frequencies is potential huge. I usually work in the audio
> frequency range (20Hz to 20kHz), but concepts apply at any frequency
> (although when you get into the GHz range, other factors become hugely
> significant).
> >
> > The range of component values of course depends on the frequency range. I
> generally use capacitors in 100pF to 10uF range (i.e. 10^-10 to 10^-5
> Farads). Resistors are typically in the 1kOhm to 1MOhm range. The choice of
> values often depends on other factors, such as the desired input impedance.
> >
> > Stefan
> >
> > dieswartdose wrote:
> > > Stefan,
> > > I am quietly studying slide rule design at the present, and your
> problem
> > > interests me. I can imagine that in times gone by some component
> > > manufacturer might well have supplied a specialist slide rule to do
> > > this calculation. In part the feasibility of such a rule depends on the
> > > range of values of the variables. What range of frequency, resistance
> > > and capacitance values do you normally encounter? Although in theory
> > > there is an infinite number of resistance and capacitance combinations
> > > for any given frequency, in practice you must have maximum and minimum
> > > values determined by cost, size, availability, etc.
> > >
> > > Peter Johnson
> >
> > --
> > Stefan Vorkoetter
> > http://www.stefanv.com
> >
>
>
>

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