Reply by Tom Del Rosso●December 22, 20152015-12-22
Ecnerwal wrote:
> In article <n5a3t6$hgs$1@dont-email.me>,
> "Tom Del Rosso" <fizzbintuesday@that-google-mail-domain.com> wrote:
>
>> M Philbrook wrote:
>>>
>>> Sounds to me the coconut business is slowing.
>>
>> Maybe the migrating swallows will bring more.
>
> African or European swallows?
Only an African swallow could possibly carry the weight.
If anybody ever asks you for the capital of Abyssinia, don't sweat.
Just say, "What do you mean? The modern capital or one of the many
ancient capitals."
It's a shame that guy didn't think of this.
--
Reply by Joe Hey●December 22, 20152015-12-22
On Mon, 21 Dec 2015 18:26:56 -0500
M Philbrook <jamie_ka1lpa@charter.net> wrote:
> In article <20151221184958.21849587.joehey@mailinator.com>,
> joehey@mailinator.com says...
> >
> > On Sun, 20 Dec 2015 22:16:53 -0500
> > "Tom Del Rosso" <fizzbintuesday@that-google-mail-domain.com> wrote:
> >
> > > Joe Hey wrote:
> > > > On Sun, 20 Dec 2015 16:34:36 -0500
> > > > "Tom Del Rosso" <fizzbintuesday@that-google-mail-domain.com>
> > > > wrote:
> > > >
> > > >> Tom Del Rosso wrote:
> > > >>> John Larkin wrote:
> > > >>>> On Sat, 19 Dec 2015 10:52:07 -0500 (EST), bitrex
> > > >>>> <bitrex@de.lete.earthlink.net> wrote:
> > > >>>>
> > > >>>>>
> > > >>>>> I'm buidling a little relaxaton oscillator for a project
> > > >>>>> using a cd4093 quad nand gate with schmitt trigger inputs.
> > > >>>>> I'm using a 200 ohm resistor and a 100n cap in the RC
> > > >>>>> network.
> > > >>>>
> > > >>>> 200 ohms is way too low. Scale up R and scale down C, by
> > > >>>> 20:1 at least.
> > > >>>
> > > >>> Here's another stupid question from me. If the output
> > > >>> impedance inflates the value of his R then why is his
> > > >>> frequency lower than he calculated?
> > > >>
> > > >> Nevermind. I wrote that a few seconds ago standing on my head.
> > > >>
> > > >
> > > > Thot so. I couldn't believe what I was reading. :)
> > >
> > > I'm having a lot of senior moments lately. It's got me a little
> > > worried frankly, but worrying about things might be the reason.
> > >
> >
> > A tablespoon of coconut oil a day keeps Alzheimer away[1][2][3].
> >
> > joe
> >
> >
> > [1] http://www.alzheimers.net/2013-05-29/coconut-oil-for-alzheimers/
> > [2] http://www.ncbi.nlm.nih.gov/pubmed/26667739
> > [3] http://www.ncbi.nlm.nih.gov/pubmed/25997382
>
> If only you can remember to take it!
>
> Now what was it we were talking about?
>
> Sounds to me the coconut business is slowing.
Nah, that's all conspiracy. :)
joe
> Jamie
>
Reply by Robert Baer●December 22, 20152015-12-22
Phil Hobbs wrote:
> On 12/19/2015 04:17 PM, Robert Baer wrote:
>> bitrex wrote:
>>>
>>> I'm buidling a little relaxaton oscillator for a project using a
>>> cd4093 quad nand gate with schmitt trigger inputs. I'm using a
>>> 200 ohm resistor and a 100n cap in the RC network.
>>>
>>> If I've done my calculations correctly, I was hoping to have an
>>> oscillator at around 30kHz. But my frequency counter is only
>>> showing around 8. Supply voltage is 5V.
>>>
>>> I understand that the frequency is dependent on the hysteresis
>>> thresholds, which are device dependent, but I didn't expect it to
>>> be that far off. Anything to check?
>>>
>>> Can I drop a crystal or ceramic resonator across the resistor to
>>> "lock" the frequency?
>>>
>> For practical purposes, the threshold(s) are one-half of the CMOS
>> supply voltage (at room temp).
>> Reasonably dependable.
>>
>
> "half" in the sense of "anywhere between one third and two thirds."
>
> Cheers
>
> Phil Hobbs
>
Hmmm..data sheet curves indicate what you said, but those i worked
with were all rather close to one half CMOS supply. Maybe because they
all were RCA and "wanted" to be contrary to those data curves?
Reply by mixed nuts●December 22, 20152015-12-22
On 12/21/2015 9:33 PM, Ecnerwal wrote:
> In article <n5a3t6$hgs$1@dont-email.me>,
> "Tom Del Rosso" <fizzbintuesday@that-google-mail-domain.com> wrote:
>> M Philbrook wrote:
>>>
>>> Sounds to me the coconut business is slowing.
>>
>> Maybe the migrating swallows will bring more.
>
> African or European swallows?
>
Barn.
--
Grizzly H.
Reply by Ecnerwal●December 21, 20152015-12-21
In article <n5a3t6$hgs$1@dont-email.me>,
"Tom Del Rosso" <fizzbintuesday@that-google-mail-domain.com> wrote:
> M Philbrook wrote:
> >
> > Sounds to me the coconut business is slowing.
>
> Maybe the migrating swallows will bring more.
African or European swallows?
--
Cats, coffee, chocolate...vices to live by
Please don't feed the trolls. Killfile and ignore them so they will go away.
Reply by ●December 21, 20152015-12-21
On Saturday, December 19, 2015 at 10:52:34 AM UTC-5, bitrex wrote:
> I'm buidling a little relaxaton oscillator for a project using a
> cd4093 quad nand gate with schmitt trigger inputs. I'm using a
> 200 ohm resistor and a 100n cap in the RC network.
>
> If I've done my calculations correctly, I was hoping to have an
> oscillator at around 30kHz. But my frequency counter is only
> showing around 8. Supply voltage is 5V.
>
> I understand that the frequency is dependent on the hysteresis
> thresholds, which are device dependent, but I didn't expect it to
> be that far off. Anything to check?
The other guys have already straightened you out on not loading 4000
CMOS with 200 ohms.
As far as depending on hysteresis, you can make the oscillator largely
independent of hysteresis and thresholds by greatly increasing the
voltage swing across the timing cap.
I solved that problem from scratch a few months ago, only to find
I'd been beaten by, um, thirty years or so...
This oscillator...
Fig. 1
======
|\
.----| >o--+-->
| |/ |
| Rt
| |
'----------+
|
--- Ct
---
|
---
has a timing swing across timing cap Ct equal to merely the hysteresis
voltage, a small and highly variable quantity that varies with Vdd.
Fig. 2
======
If you drive Ct's "cold" end with a buffer, though, you increase the swing
by Vdd in each direction, making the timing dramatically less dependent on
threshold or hysteresis.
R1 is a high value resistor to prevent the CMOS gate's input diodes from
conducting and spoiling the R*C time constant. For accuracy, most of
the timing current should flow thru Rt, thus, R1 >= 3 or 4*Rt.
|\ |\
.-- R1 --| >o--+---| >o--+-->
| |/ | |/ |
| Rt |
| | Ct |
'--------------+----||---'
The resulting behavior is surprisingly close to ideal.
Cheers,
James Arthur
Reply by Tom Del Rosso●December 21, 20152015-12-21
M Philbrook wrote:
>
> Sounds to me the coconut business is slowing.
Maybe the migrating swallows will bring more.
--
Reply by M Philbrook●December 21, 20152015-12-21
In article <20151221184958.21849587.joehey@mailinator.com>,
joehey@mailinator.com says...
>
> On Sun, 20 Dec 2015 22:16:53 -0500
> "Tom Del Rosso" <fizzbintuesday@that-google-mail-domain.com> wrote:
>
> > Joe Hey wrote:
> > > On Sun, 20 Dec 2015 16:34:36 -0500
> > > "Tom Del Rosso" <fizzbintuesday@that-google-mail-domain.com> wrote:
> > >
> > >> Tom Del Rosso wrote:
> > >>> John Larkin wrote:
> > >>>> On Sat, 19 Dec 2015 10:52:07 -0500 (EST), bitrex
> > >>>> <bitrex@de.lete.earthlink.net> wrote:
> > >>>>
> > >>>>>
> > >>>>> I'm buidling a little relaxaton oscillator for a project using a
> > >>>>> cd4093 quad nand gate with schmitt trigger inputs. I'm using a
> > >>>>> 200 ohm resistor and a 100n cap in the RC network.
> > >>>>
> > >>>> 200 ohms is way too low. Scale up R and scale down C, by 20:1 at
> > >>>> least.
> > >>>
> > >>> Here's another stupid question from me. If the output impedance
> > >>> inflates the value of his R then why is his frequency lower than
> > >>> he calculated?
> > >>
> > >> Nevermind. I wrote that a few seconds ago standing on my head.
> > >>
> > >
> > > Thot so. I couldn't believe what I was reading. :)
> >
> > I'm having a lot of senior moments lately. It's got me a little
> > worried frankly, but worrying about things might be the reason.
> >
>
> A tablespoon of coconut oil a day keeps Alzheimer away[1][2][3].
>
> joe
>
>
> [1] http://www.alzheimers.net/2013-05-29/coconut-oil-for-alzheimers/
> [2] http://www.ncbi.nlm.nih.gov/pubmed/26667739
> [3] http://www.ncbi.nlm.nih.gov/pubmed/25997382
If only you can remember to take it!
Now what was it we were talking about?
Sounds to me the coconut business is slowing.
Jamie
Reply by John Larkin●December 21, 20152015-12-21
On Sun, 20 Dec 2015 16:34:36 -0500, "Tom Del Rosso"
<fizzbintuesday@that-google-mail-domain.com> wrote:
>Tom Del Rosso wrote:
>> John Larkin wrote:
>>> On Sat, 19 Dec 2015 10:52:07 -0500 (EST), bitrex
>>> <bitrex@de.lete.earthlink.net> wrote:
>>>
>>>>
>>>> I'm buidling a little relaxaton oscillator for a project using a
>>>> cd4093 quad nand gate with schmitt trigger inputs. I'm using a
>>>> 200 ohm resistor and a 100n cap in the RC network.
>>>
>>> 200 ohms is way too low. Scale up R and scale down C, by 20:1 at
>>> least.
>>
>> Here's another stupid question from me. If the output impedance
>> inflates the value of his R then why is his frequency lower than he
>> calculated?
>
>Nevermind. I wrote that a few seconds ago standing on my head.
Darn, I was fixed to jump all over that one.
The bigger question is why the waveform at the cap is such a nice
triangle.
--
John Larkin Highland Technology, Inc
picosecond timing precision measurement
jlarkin att highlandtechnology dott com
http://www.highlandtechnology.com
Reply by Joe Hey●December 21, 20152015-12-21
On Sun, 20 Dec 2015 22:16:53 -0500
"Tom Del Rosso" <fizzbintuesday@that-google-mail-domain.com> wrote:
> Joe Hey wrote:
> > On Sun, 20 Dec 2015 16:34:36 -0500
> > "Tom Del Rosso" <fizzbintuesday@that-google-mail-domain.com> wrote:
> >
> >> Tom Del Rosso wrote:
> >>> John Larkin wrote:
> >>>> On Sat, 19 Dec 2015 10:52:07 -0500 (EST), bitrex
> >>>> <bitrex@de.lete.earthlink.net> wrote:
> >>>>
> >>>>>
> >>>>> I'm buidling a little relaxaton oscillator for a project using a
> >>>>> cd4093 quad nand gate with schmitt trigger inputs. I'm using a
> >>>>> 200 ohm resistor and a 100n cap in the RC network.
> >>>>
> >>>> 200 ohms is way too low. Scale up R and scale down C, by 20:1 at
> >>>> least.
> >>>
> >>> Here's another stupid question from me. If the output impedance
> >>> inflates the value of his R then why is his frequency lower than
> >>> he calculated?
> >>
> >> Nevermind. I wrote that a few seconds ago standing on my head.
> >>
> >
> > Thot so. I couldn't believe what I was reading. :)
>
> I'm having a lot of senior moments lately. It's got me a little
> worried frankly, but worrying about things might be the reason.
>