--- In Electronics_101@..., "Roy J. Tellason"
<rtellason@b...> wrote:

On Tuesday 02 March 2004 04:02 pm, davidglaister wrote:

Hi,

I posted a message a week or so ago asking for advice on the

timing

of a 555 timer to drive a UNC5804 stepper motor driver. With the
advice from this group, and some trial and error I now have the
motor functioning as needed - thanks.

The next thing I would like to do is connect a velleman K8035
up/down counter so I can keep track of the position of the

stepper

motor.

What is this counter, a chip? Something else? I'm not familiar

with the

name you mention.

On the stepper motor circuit the 555 sends a pulse to the UCN5804
that then drives the motor forwards or backwards depending on the
whether pin 14 of the 5804 is fed +5v or 0v.

The counter circuit counts down if wire 8 is pulsed, or up if

wire 9

is pulsed.

There are TTL counter chips which work the same way, and others

that have a

single clock input and a direction input, which probably matches

up with

what you're feeding the motor.

Would it be possible to drive the couter up/down from the

stepper motor

circuit (I hope this makes sense). The problem is wire 8 or 9

would have to

be pulsed depending on the state of pin 14 (diode, transistor?)

Probably easier with a small number of logic gates.

I'm not sure if the wires of the counter circuit require +v or -

v,

the instructions state:

"counting pulses can be applied to the unit by applying +3v to

+12v

pulses with respect to ground"

Sounds like it's looking for a positive pulse.

Tell me more about this counter?

Hi,

Thanks you for the reply.

A link to the counter instructions:


A link to the driver circuit:


As for a counter that has a pulse input and direction input, I have
found this circuit:


But from what I have read on the web, it may not be suitable
beacause of the "debounce" built into the circuit (or PIC).

David

On Tuesday 02 March 2004 04:02 pm, davidglaister wrote:

Hi,

I posted a message a week or so ago asking for advice on the timing
of a 555 timer to drive a UNC5804 stepper motor driver. With the
advice from this group, and some trial and error I now have the
motor functioning as needed - thanks.

The next thing I would like to do is connect a velleman K8035
up/down counter so I can keep track of the position of the stepper
motor.

What is this counter, a chip? Something else? I'm not familiar with the
name you mention.

On the stepper motor circuit the 555 sends a pulse to the UCN5804
that then drives the motor forwards or backwards depending on the
whether pin 14 of the 5804 is fed +5v or 0v.

The counter circuit counts down if wire 8 is pulsed, or up if wire 9
is pulsed.

There are TTL counter chips which work the same way, and others that have a
single clock input and a direction input, which probably matches up with
what you're feeding the motor.

Would it be possible to drive the couter up/down from the stepper motor
circuit (I hope this makes sense). The problem is wire 8 or 9 would have to
be pulsed depending on the state of pin 14 (diode, transistor?)

Probably easier with a small number of logic gates.

I'm not sure if the wires of the counter circuit require +v or -v,
the instructions state:

"counting pulses can be applied to the unit by applying +3v to +12v
pulses with respect to ground"

Sounds like it's looking for a positive pulse.

Tell me more about this counter?

开云体育

Hi,

I posted a message a week or so ago asking for advice on the timing
of a 555 timer to drive a UNC5804 stepper motor driver. With the
advice from this group, and some trial and error I now have the
motor functioning as needed - thanks.

The next thing I would like to do is connect a velleman K8035
up/down counter so I can keep track of the position of the stepper
motor.

On the stepper motor circuit the 555 sends a pulse to the UCN5804
that then drives the motor forwards or backwards depending on the
whether pin 14 of the 5804 is fed +5v or 0v.

The counter circuit counts down if wire 8 is pulsed, or up if wire 9
is pulsed. Would it be possible to drive the couter up/down from the
stepper motor circuit (I hope this makes sense). The problem is wire
8 or 9 would have to be pulsed depending on the state of pin 14
(diode, transistor?)

I'm not sure if the wires of the counter circuit require +v or -v,
the instructions state:

"counting pulses can be applied to the unit by applying +3v to +12v
pulses with respect to ground"

Thanks again for your help, David

--- In Electronics_101@..., "Bene Tam" <bene-tam@d...>
wrote:

hi all

I am a firmware engineer, recently my power adapter for the laptop

is broken

Although I am going to buy a new one out there, i would like to

find out how to build a simple substitute.

There should be 3 stage, right?? AC-AC, then AC-DC, then DC-DC

stage 1, use transformer, say turn ratio 5:1 to lower the voltage

to 18VAC-48VAC, right?

stage 2, use bridge rectifier to convert the AC to DC, the outcome

will be 24-68VDC, right??

but is there any combined alternative for stage 1 and 2?? seems

some sort of switching technique out there?!

stage 3, use some sort of IC, just those from national semi. or

other MOS switching circuit to convert that to exactly 20VDC3A
output, right?? this stage is the most difficult to me, anyone can
tell me more detail??

Thanks much

Check your current requirements and your voltage requirements.

Most likly, the laptop will run on 12 and 5 VDC like home machines
and possibly, 5 and 3.5 v.

Since you also, PROBABLY do not need anything more than 12 VDC, don't
generate 24VDC on your second stage. Using a LM7812 and LM7805 will
drop the voltage to 12VDC and 5VDC regulated, but will shed a LOT of
heat.

A dual transformer to get 6 and 12 volts will offer a much lower
voltage to start with.

A simple power supply is just AC to AC via the transformers like you
mentioned.

Then a bridge rectifier or 4 diodes arranged in a bridge. This
yields DC voltage.

Add to that a capacitor that is rated for double the voltage you
expect. Search this list for "Mariss" or "80,000" and find the post
that referrs to how to size the capacitor.

Then after cap, run the DC voltge into a voltge regulator such as a
LM7812 to get 12 VDC regulated.

Check the specs for amperage for the voltage regulator(s).

None of this is rocket science and is a good E-101 project.

Dave

Heinz,
Sorry couldn't mail earlier. Please check this page for more
info

You will find the desinger's email address there. Also you can download
the zip file of the full entry from that page.

hope this helps
-anmol

Not necessarily. All CRT VGA monitors are analog input, and most LCD
monitors have analog inputs.

However, you are correct about just getting a TV card. The original
poster would have to build most of a TV plus a computer to do what he
wants. A tuner with control circuits, IF strip, then split up the
received signal into H and V and R, G, and B, then digitize all that
in preparation to digitally rescan it to VGA frequencies.

Alien Steve

--- In Electronics_101@..., "ksrao_iete" <ksrao_iete@y...>
wrote:

you cant do it anyway since monitor contains digital elements if you
wanna do it anyway use tv card available in market.




--- In Electronics_101@..., <av1a@g...> wrote:

Hmm , ....this would be interesting

have you tried www.epanorama.net video section.

imran
-----Original Message-----
From: ejazabidi@y... [mailto:ejazabidi@y...]
Sent: Monday, October 29, 2001 7:59 AM
To: Electronics_101@...
Subject: [Electronics_101] Re: tv to vga


--- In Electronics_101@y..., "yahoo" <yahoo@c...> wrote:
>
> >i need a circuit which convert my monitor into tv receiver.
> >i will be very thankfull.
>
>
> Do you want your VGA monitor receive RF television signals

(like

channels 2-13) or just make a circut to convert NTSC video to VGA?

helo
yes i want my vga monitor receive rf tv signals. will u help me

to

find a circuit for that?
thanx



To unsubscribe from this group, send an email to:
Electronics_101-unsubscribe@...



Your use of Yahoo! Groups is subject to the Yahoo! Terms of

Service.

In a previous life, before Disney & before downsizing,
I was a video systems designer for ABC. We had a
saying that "There's never enough money to do it
right, but there's always enough money to fix it
later". Eventually the system (control room, intercom
system, truck) worked properly, but it was
frustrating. Now however, with outsourcing produced
projects, you'd better get it right the first time,
because that's the way it's going to be. The cost is
lower, but so is the usability & reliability.



--- peter tremewen <Ptremewe@...> wrote:

The problem with the "cost reduction is
king" approach I have always found, is that when it
eventually does fail, you are the one who wears the
blame for the fault. Clients don't wont to know that
it broke down cause they didn't want to pay a few
extra dollars for surge protection. Whenever a
client comes up to me and says "I can get it cheaper
down at blah, Blah" I simply tell them that I sell
middle of the range equipment and that the slight
extra expense is worth it when you consider the cost
of break down. I consider the few clients I loose
because of this are just not worth the trouble they
will cause latter...... When I am asked to do so, I
have a reputation for producing reasonable quality
reliable equipment..... Most people, especially
those who I have previously dealt with, are willing
to pay just a little bit more for that I have
found......

The Sinister Dragon

Of COURSE surge protection, and a gazillion other
things besides, are in
order. But in most industrial environments, cost
reduction is king, and the
bean counters in the front office get to say which
costs get "reducted" and
which don't.

In other words, that's why we sub a few .10
1N4007s into circuits, and have
quit trying (except for a few notable cases) to
sell large-scale protection
to most industrial clients. They just aren't
interested.

-DM

__________________________________
Do you Yahoo!?
Yahoo! Search - Find what you?re looking for faster

u r right please proceed with utmost care

--- In Electronics_101@..., "ghidera2000"
<ghidera2000@y...> wrote:

--- In Electronics_101@..., "upand_at_them"
<upand_at_them@y...> wrote:

I want to use a Multimedia Card (3.3V, SPI) in a circuit that's
mostly 5V. Is there a simple IC that does the level shifting?

Mike

I was just playing with that sort of thing. Couple possibilities:

Simple way: Run your 5v signal through a resistor and a 3.3 zener
diode to ground. Go from the zener to your 3.3 device. Resistor size
depends on the current requirements of your 3.3 device. If its just
communications then a 10k resistor should be fine.

The slightly more complicated method was to use a 74hc245/244
powered from the 3.3 volt side. Your 5v inputs to it need to run
through some honkin' resistors (like 1 meg) though. The 244 will
latch up to 5v and push your whole 3.3 circuit to 5v if you dont
massively limit the current on the 5v side.

Seeing the 74hct4245 link in the previous message though, I'd say
forget the 245 - much safer with the other chip or the diode method.

The problem with using resistors on signal lines is speed. The inputs
and the traces are largly capacitive so added resistance on digital
signal lines slows down the rise and fall times dramatically.

开云体育

you cant do it anyway since monitor contains digital elements if you
wanna do it anyway use tv card available in market.









--- In Electronics_101@..., <av1a@g...> wrote:

Hmm , ....this would be interesting

have you tried www.epanorama.net video section.

imran
-----Original Message-----
From: ejazabidi@y... [mailto:ejazabidi@y...]
Sent: Monday, October 29, 2001 7:59 AM
To: Electronics_101@...
Subject: [Electronics_101] Re: tv to vga


--- In Electronics_101@y..., "yahoo" <yahoo@c...> wrote:
>
> >i need a circuit which convert my monitor into tv receiver.
> >i will be very thankfull.
>
>
> Do you want your VGA monitor receive RF television signals

(like

channels 2-13) or just make a circut to convert NTSC video to VGA?

helo
yes i want my vga monitor receive rf tv signals. will u help me

to

find a circuit for that?
thanx



To unsubscribe from this group, send an email to:
Electronics_101-unsubscribe@...



Your use of Yahoo! Groups is subject to the Yahoo! Terms of

Service.

Sheesh. Is THAT all?

;o)

-DM

Really busy. I'm researching everything I need to build a doppler RDF
including microstrip/patch antennas and small loop antennas, gated
integrators, and a load of other stuff that I need refreshers on.
While getting my graphics business shifted over to doing imprinting
(tshirts, mugs, etc). Plus my wife and one of the schools here wants
me to come in and do some science classes. And I am attempting to set
up a video capture/editing computer in my spare time with nearly zero
money. And learning to program PICs for use in props and test equipment.

And that's a small fraction of the pies I have my fingers in.

Look for links on microstriplines, small antennas, and anything else
related to my project.

Alien Steve

--- In Electronics_101@..., "dangermouse"
<dangermouse1956@g...> wrote:

Good man. You've been busy lately, huh?

-DM

----- Original Message -----
From: "Steve" <alienrelics@y...>
To: <Electronics_101@...>
Sent: Monday, March 01, 2004 12:48 PM
Subject: [Electronics_101] Converting graphics to web formats

--- In Electronics_101@..., "dangermouse"
<dangermouse1956@g...> wrote:

You might also have been thinking about Irfanview, also free and

quite good.

-DM

That's the one! I changed the folder named CAD to CAD and Graphics,
moved your link for SmartDraw in there, and put a link to IrfanView.

Alien Steve





Yahoo! Groups Links

开云体育

On Monday 01 March 2004 02:41 pm, dangermouse wrote:

Perhaps that's true for consumer-type work, but in industrial environments,
which are notoriously nasty (chemically, thermally and electrically) that
1000V PIV is wonderful for preventing failures due to the guy down the hall
starting and stopping his welder and other such stuff.

Oh sure, if I'm gonna buy some I'll probably just go ahead and get the 1000V
parts, the price difference just isn't worth it...

Though if the industrial environment in question is *that* nasty then maybe
surge protection is in order, before it gets to the rectifiers...

You're right, it's 1N4007. When Peter said 4008, I just parroted him rather
than check it for myself.

See? It's someone else's fault. I never make misteaks myself...

-DM

Perhaps that's true for consumer-type work, but in industrial environments,
which are notoriously nasty (chemically, thermally and electrically) that
1000V PIV is wonderful for preventing failures due to the guy down the hall
starting and stopping his welder and other such stuff.

-DM

On Monday 01 March 2004 01:44 pm, mattnyc_ wrote:

Hello,

I'm new to electronics and would love a little hands on help. I was
wondering if anyone living in or near White Plains (westchester) or
NYC would be willing to be a mentor.

Heh. I used to live in that county, but I ain't moving back there to help
you out! :-) What is it that you're trying to do?