Driver to drive?

In article <eae1s0pp9kihio2990hd7qqgf1itan7fkh@4ax.com>,
James Roberts <jayrob@electrotran.com> wrote:
In general terms, what is the preferred design approach for minimizing
phase distortion when using a second order active LPF?

In this case it is a PWM audio signal from a PIC micro.
Click to expand...
Otheres will certainly talk about the analog side. You have a PWM signal
from a micro and that may open up another opertunity. If the signals are
being made by a PIC, you may be able to shift the phase of some
frequencies in the digital side. This could let you take out some of the
nonlinearities in the phase, have a sharp cut off and not add stages.

--
--
kensmith@rahul.net forging knowledge
 
In article <10s1gmbke88q16@corp.supernews.com>,
Tim Wescott <tim@wescottnospamdesign.com> wrote:
[...]
There are some 5th-order monolithic filters out there, but I can't
recall who makes them.
Click to expand...
Linear makes one where the frequency can be set to N*10KHz up to 150KHz.

--
--
kensmith@rahul.net forging knowledge
 
On Wed, 15 Dec 2004 15:03:53 -0800, Tim Wescott
<tim@wescottnospamdesign.com> wrote:

James Roberts wrote:

In general terms, what is the preferred design approach for minimizing
phase distortion when using a second order active LPF?

In this case it is a PWM audio signal from a PIC micro.

Thanks for your reply.

James

Run screaming?

Your best bet is to use a filter with higher damping. With a strictly
low-pass filter (actually with any filter that has no unstable zeros)
Click to expand...
What are "unstable zeros"?

the shape of the phase response is exactly determined by the shape of
the amplitude response.

Seach for "Gaussian filter". You'll be dismayed at the fact that your
shape factor will get worse, not better. Live with it.

There are some 5th-order monolithic filters out there, but I can't
recall who makes them.
Click to expand...
 
Ken Smith wrote:

In article <10s1gmbke88q16@corp.supernews.com>,
Tim Wescott <tim@wescottnospamdesign.com> wrote:
[...]

There are some 5th-order monolithic filters out there, but I can't
recall who makes them.


Linear makes one where the frequency can be set to N*10KHz up to 150KHz.

There are a bunch of switched-capacitor filters out there, but
Click to expand...
switched-capacitor filters can have aliasing problems. The one I was
thinking of is an all-linear one. I was a system engineer on the
project that it was used on, and there was a whole bunch of stuff going
on around me, so I only paid attention to the fact that it existed, not
who made it.

--

Tim Wescott
Wescott Design Services
http://www.wescottdesign.com
 
The Phantom wrote:

What are "unstable zeros"?


Do you know what poles and zeros are in a circuit design or dynamic
Click to expand...
systems context? If so, an unstable zero is simply a zero with a
positive real part (or who's magnitude is greater than one in a
sampled-time system).

If you _don't_ know about poles and zeros and the Laplace domain, an
unstable zero makes a system respond to an input with more than the
minimum amount of phase shift necessary to get a certain amplitude
response -- that's a circular definition given my original assertion,
but I can't think of a better way to put it. A system with a single
large unstable zero will respond to any initial push by going backwards
from the direction it ends up going in response to the push.

--

Tim Wescott
Wescott Design Services
http://www.wescottdesign.com
 
In article <10s3fh8etr67of5@corp.supernews.com>,
Tim Wescott <tim@wescottnospamdesign.com> wrote:
Ken Smith wrote:

In article <10s1gmbke88q16@corp.supernews.com>,
Tim Wescott <tim@wescottnospamdesign.com> wrote:
[...]

There are some 5th-order monolithic filters out there, but I can't
recall who makes them.


Linear makes one where the frequency can be set to N*10KHz up to 150KHz.

There are a bunch of switched-capacitor filters out there, but
switched-capacitor filters can have aliasing problems. The one I was
thinking of is an all-linear one.
Click to expand...
The LT1564 I suggested is continuous time.

--
--
kensmith@rahul.net forging knowledge
 
Ken Smith wrote:
In article <10s3fh8etr67of5@corp.supernews.com>,
Tim Wescott <tim@wescottnospamdesign.com> wrote:

Ken Smith wrote:


In article <10s1gmbke88q16@corp.supernews.com>,
Tim Wescott <tim@wescottnospamdesign.com> wrote:
[...]


There are some 5th-order monolithic filters out there, but I can't
recall who makes them.


Linear makes one where the frequency can be set to N*10KHz up to 150KHz.


There are a bunch of switched-capacitor filters out there, but
switched-capacitor filters can have aliasing problems. The one I was
thinking of is an all-linear one.


The LT1564 I suggested is continuous time.

That's probably the one I was thinking of then -- IIRC it was a Linear
Click to expand...
part and it was kinda unique.

--

Tim Wescott
Wescott Design Services
http://www.wescottdesign.com
 
Jim Thompson wrote:

[snip]

Butter and olive oil, and wine, are good for you. Margarine and
bi-sulfite preservatives are not.
Click to expand...
Bi-sulphates may not be good for you but bi-carbonates are. They get rid of the
heartburn caused by eating all the other good substances such as butter, pork
scratchings (pig skins), full fat milk and burgers.

Gibbo
 
On 16 Dec 2004 22:06:40 GMT, chrisgibbogibson@aol.com
(ChrisGibboGibson) wrote:

Jim Thompson wrote:

[snip]

Butter and olive oil, and wine, are good for you. Margarine and
bi-sulfite preservatives are not.


Bi-sulphates may not be good for you but bi-carbonates are. They get rid of the
heartburn caused by eating all the other good substances such as butter, pork
scratchings (pig skins), full fat milk and burgers.

Gibbo
Click to expand...
Some of us who were raised on such stuff don't need bi-carbs ;-)

...Jim Thompson
--
| James E.Thompson, P.E. | mens |
| Analog Innovations, Inc. | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| Phoenix, Arizona Voice:(480)460-2350 | |
| E-mail Address at Website Fax:(480)460-2142 | Brass Rat |
| http://www.analog-innovations.com | 1962 |

I love to cook with wine. Sometimes I even put it in the food.
 
Bhanu Prakash wrote...
I want to develop an miswiring protection ckt for my regulator
that was used inside my application board. Please go through
the below CKT.
(MTP23p06VDS)
S D
-------------------------->Mosfet-------------- O/P
| |
| G |
| R1= ? |
-------^^^^^^---------------|
| |
| |
| ^
24vdc ^
| R2=? ^
| ^
| |
| | GND
-----------------------------|-------------------

The mosfet(MTP23p06VDS) that was used in the above ckt has
the following specifications.

Drain–to–Source Voltage--------------------- VDSS 60 Vdc
Drain–to–Gate Voltage (RGS = 1.0 MW)-------- VDGR 60 Vdc
Gate–to–Source Voltage
– Continuous ----------ą 15 Vdc
– Non–repetitive-------ą 25 Vpk
Drain Current – Continuous @ 25°C ---------23A

The output from mosfet drain and the GND are going to my regulator
input pins. My question is here, how can i calculate here the
resistor values R1 and R2. Please Give me your valuable suggestions.
Click to expand...
That's a p-channel FET, and the circuit will work properly, acting
as a low-resistance passthrough for the correct input polarity and
as an open circuit for the wrong polarity. Provided, as you say,
the gate voltage is correctly applied. Given that your 24V source
may sag, and it certainly isn't 24V during startup, it's preferable
to employ a zener in the gate-drive circuit, IMHO.

We prefer to think of power and current flow from left to right,
source to load, like this.

.. P-channel POLARITY-PROTECTION SWITCH
.. mosfet
.. + (O)------- D S ---+---+---> + The FET comes on early,
.. G \_|_ | shorting out the substrate
.. 24V power | /_\ 22k diode that otherwise
.. source |______|___| carries the current in
.. | 12V to the desired direction.
.. 3.3k zener LOAD
.. |
.. - (O)----------+--------------> -

The 22k resistor insures 0V on the gate during power off.

Normally a p-type FET conducts in the other direction, but this
circuit works because of the principle that a power MOSFET can
carry current in either direction when it's turned on.


--
Thanks,
- Win
 
Fred Bloggs wrote:

View in a fixed-width font such as Courier.


.
.
. __
. +------------+-------\ \
. | | | o->CLOSE
. +--4013-+ | +--4013--+ | +---/__/
. | | +-|D /Q|-+ |
. | | | | | __
. +------+-------+---|CK Q|----|CK Q|---------\ \
. | | | | | | FF | | | o->OPEN
. | [1K] | | ONE | | | +---/__/
. | | | | SHOT | | SET RST| |
. | GND | +-------+ +--------+ |
. | | | | |
. | | | | |
. | +--------------------------+ |
. | |TGL C O| | 12V
. | | | | |
. T | EXT>--|EXT | | +-----+
. O | | EXTERNAL OVERDRIVE | | | |
. G o | | | [10K] e
. G |- | OL CL SODR | | | |/
. L o +--------------------------+ | +---|
. E | | | | | | |\
. | | | | | [10K] c
. | | | | | | |
. | | | | +-----+ | | |
. | | | +--------|R Q|----+---+ |
. | | | | | |
. | C.LIMIT | | | NOR_| +-RUN
. +----o/ o------------+---|>|--+-----|S Q| |
. | | | | +-----+ [1K]
. | | | | STOP-LATCH |
. | O.LIMIT | | | GND
. 12V-+----o/ o------+---------|>|--+
. | | | |
. | | | |
. | STOP | | |
. +--o o-------|-----|--------+
. --- | | |
. | [10K] [10K] [1K]
. | | |
. GND GND GND
.
.
Click to expand...
It may be better to require that TOGGLE be held down with automatic STOP
when it is released. Then you get your reversing action and stop in a
single switch. A TGL2 input to the SODR logic has been added to debounce
that output, and this should be included in the previous schematic as
well. The circuit now looks like this:
View in a fixed-width font such as Courier.

.
. __
. +------------+-------\ \
. | | | o->CLOSE
. +--4013-+ | +--4013--+ | +---/__/
. TOGGLE | | +-|D /Q|-+ |
. -+- | | | | | __
. +---o o----+-----+-|CK Q|-+--|CK Q|---------\ \
. | | | | | | | FF | | | o->OPEN
. | [1K] | | ONE | | | | +---/__/
. | | | | SHOT | | | SET RST| |
. | GND | +-------+ | +--------+ |
. | | | | | |
. | | | | | |
. | | | | | |
. | | | | | |
. | | | | | |
. | +--------------------------+ |
. | | TGL1 TGL2 C O| |
. | | | |
. | EXT>-|EXT | |
. | | EXTERNAL OVERDRIVE | |
. | | | |
. | | OL CL SODR | |
. | +--------------------------+ |
. | | | | |
. | | | | |
. | | | +-------------------+
. | | |
. | C.LIMIT | |
. +----o/ o------------+
. | | |
. | | |
. | O.LIMIT | |
. 12V-+----o/ o------+ |
. | |
. [10K] [10K]
. | |
. GND GND
.
.
.
. +--------------------- EXTERNAL OVERDRIVE --------------------+
. | __ |
. | OL --------------------------------------------\ \ |
. | | >- C |
. | +--------------/__/ |
. | | __ |
. | CL -----------------------------|--------------\ \ |
. | | | >- O |
. |TGL2--------|>|----+ | +----------/__/ |
. | | | | |
. |TGL1-------[10K]---+-------------|---|-------+ |
. | __ | | | |
. |EXT ---+---|>|---+-------\ \ | | | |
. | | | | o---|---+ | |
. | OL ---|---------|-------/__/ | | | |
. | | | | | | __ |
. | | | | | __ +--\ \ |
. | | | __ | +--\ \ | o-SODR |
. | CL ---|---------|-------\ \ | | >---/__/ |
. | +-\ \ | | o---+------/__/ |
. | | | o---|-|>|-+-/__/ |
. | +-/__/ | | |
. | | | |
. | | | CLOSE |
. | | | ----- |
. | [10K] [10K] | | |
. | EXT | | EXT-> | | |
. | OPEN=OFF +-----+ | | |
. | | OPEN | | OPEN |
. | EXT SW __ | ----- ------ |
. | +12V--o/ o--+-\ \ | |
. | | | o --+ (from LDR ckt ) |
. | +-/__/ |
. | | |
. | [10K] |
. | | |
. | GND |
. +-------------------------------------------------------------+
.
 
Any idea how makes Sandisk's MP3 player for them? Or, who makes the
controller chip? I do not think its Sigmatel, but I am not sure. It
might be Philips or Texas Instruments, but cannot seem to get
confirmation of this. Anybody know??
 
Terry Pinnell wrote:
Fred Bloggs <nospam@nospam.com> wrote:



Terry Pinnell wrote:

Meanwhile here's a schematic and notes on the present power supply

http://www.terrypin.dial.pipex.com/Images/CurtainControllerSupply.gif



Can this motor be PWM'ed? You might give that a try- you need something
like 25% duty off the 12V. And since there is not a lot of difference
between stall/run current, this is even more reason to go with a thermal
fuse on the case to break the power.


I did think about PWM at one stage, but decided that it was probably a
bit OTT for a curtain controller. The motor is now running at a
reasonably 'calm' speed.

Re the stall/run delta, did you see my latest figures measurements?
They appear to show a quite large difference. My earlier 3.0/2.4A were
recalled from trying identical motor on the bench, fed from variable
power supply. I now realise that supply was probably inadequately
rated to give a reliable result. The *actual* motor is powered by a
heavier duty fixed 13V supply, via long cable pair to bedroom, and -
as you saw - measuring current proved more difficult than I'd
expected.


Getting back to the suggested circuit in this subthread- although the
LIMIT switches do not require debouncing in manual mode due to the
latching action of the 4013, they do require debouncing in EXT mode
because the bounce transmits directly through the SODR output
enabling/disabling the OPEN/CLOSE outputs.


OK, good point, thanks.


This is fixed with a 555
one-shot which catches any bounce having effect on your final relay
drivers, and it debounces the EXT MODE switch as well. Once again ,
there is no memory and operation is immune to power failures which I
assume may be of some importance to unattended operation.


I reckon my next step will be to redesign the connectors, so that I
can swap trial circuits more readily. At present, all wires go to a
set of 14 connector blocks on outside of enclosure, and then by
permanent wires to circuits. I need to isolate the relay/motor section
and make the rest easily 'pluggable'.

I'll then try your alternative circuit below, and at least the two
others from you and John Fields that are pending experiment.

I assume you saw my simulations described in
news:di3mr0lahl2g7aug1fp38ch881vucntfo2@4ax.com
and shown at
http://www.terrypin.dial.pipex.com/Images/Sim1.gif
http://www.terrypin.dial.pipex.com/Images/Sim2.gif
http://www.terrypin.dial.pipex.com/Images/Sim3.gif
http://www.terrypin.dial.pipex.com/Images/Sim4.gif
http://www.terrypin.dial.pipex.com/Images/CircuitSims1-4.gif
Click to expand...
You are not going to be able to do a toggle with just the NOR
latches-that requires a master-slave set-up, so you might as well just
use a 4013 or some other FF in the logic family.

I have yet to simulate the toggle version.
Click to expand...
It doesn't make any sense to have all those switches- too complicated.
How fast does this mechanism move the curtains? I expect it's fast if
you had to "tame" the motor. If that's the case then a single TOGGLE
with automatic stop when released has to be simpler to operate than all
this direction control with separate stop switch. If it's slow moving
then a single TOGGLE with automatic stop on release modified so that say
a 5 second hold down prevents stop on release and runs curtains to limit
would be a workable substitute.
 
"Dmitri(Cabling-Design.com)" <info_at_cabling-design_dot_com@foo.com> wrote

I'm looking for some info on whether or not anyone has attempted to make
membrane keyboards in a garage workshop environment.
Click to expand...
Usenet rule #12a: The answer to 'has anyone else...?' is 'yes'.
However, that does not mean it is a good thing to do. A DIY
membrane keyboard sounds like a lot of time and money for
a really bad keyboard.

I have a project that requires eight buttons under an LCD
Click to expand...
Use a set of 8 real switches:

http://www.cherrycorp.com/english/switches/key/mx.htm

digikey etc.

--
Nicholas O. Lindan, Cleveland, Ohio
Consulting Engineer: Electronics; Informatics; Photonics.
Remove spaces etc. to reply: n o lindan at net com dot com
psst.. want to buy an f-stop timer? nolindan.com/da/fstop/
 
I read in sci.electronics.design that Roger Lascelles
<invalidl@invalid.invalid> wrote (in <32hajeF3koan1U1@individual.net>)
about 'Homebrew membrane keypad', on Sat, 18 Dec 2004:
Commercially printed Lexan is expensive, so the
hobbiest bit might be to find a nice tough label you can print with a
laser printer. Might want to stick a sheet of clear over the laser
printing ?
Click to expand...
Print in reverse on the lower side ('second-surface printing'). OHP film
works.
--
Regards, John Woodgate, OOO - Own Opinions Only.
The good news is that nothing is compulsory.
The bad news is that everything is prohibited.
http://www.jmwa.demon.co.uk Also see http://www.isce.org.uk
 
On Sat, 18 Dec 2004 06:48:52 +0000, Rolavine wrote:

Subject: OT: A Letter To President Bush (political satire)
From: Rich Grise rich@example.net
....
If my memory is in tack,
Click to expand...
If your memory is in tack, maybe you should check for it at the feed store.
--
The Pig Bladder From Uranus, still waiting for
some hot babe to ask what my favorite planet is.
 
On Sat, 18 Dec 2004 06:05:54 GMT, Rich Grise <rich@example.net> wrote:

Thank you again for reminding us that God's word is eternal and
unchanging.
----------------------

Cheers!
Rich
Click to expand...
Ya gotta Lev it.

Izat your work or stolen from somewhere?
 
xray wrote:
On Sat, 18 Dec 2004 06:05:54 GMT, Rich Grise <rich@example.net> wrote:


Thank you again for reminding us that God's word is eternal and
unchanging.
----------------------

Cheers!
Rich


Ya gotta Lev it.

Izat your work or stolen from somewhere?
Click to expand...
Stolen, I think. I've seen it elsewhere.
 
On Sat, 18 Dec 2004 01:10:49 -0900, DeathWish wrote:

xray wrote:
On Sat, 18 Dec 2004 06:05:54 GMT, Rich Grise <rich@example.net> wrote:

Thank you again for reminding us that God's word is eternal and
unchanging.
----------------------

Cheers!
Rich

Ya gotta Lev it.

Izat your work or stolen from somewhere?


Stolen, I think. I've seen it elsewhere.
Click to expand...
It was directed at Dr Laura the first time I saw it.
--
Best Regards,
Mike
 
On Sat, 18 Dec 2004 01:10:49 -0900, DeathWish
<symphonic_nospam@gci.net> wrote:

xray wrote:
On Sat, 18 Dec 2004 06:05:54 GMT, Rich Grise <rich@example.net> wrote:


Thank you again for reminding us that God's word is eternal and
unchanging.
----------------------

Cheers!
Rich


Ya gotta Lev it.

Izat your work or stolen from somewhere?


Stolen, I think. I've seen it elsewhere.
Click to expand...
"Unattributed" might be a little more polite...

--

"What is now proved was once only imagin'd." - William Blake, 1793.
 
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