magnetic field

[Vidar Lřkken]

js5895 wrote:

Well, I have a USB to PS/2 adapter, so I hooked it up the way the
adapter was hooked up, but in reverse.

This won't work. The keyboard chip _has_ to be able to speak both usb
and ps/2. A ps/2 keyboard can't speak USB, but many usb keyboards can
speak PS/2.
Buy a usb keyboard. It costs you 10$


--
MVH,
Vidar

www.bitsex.net

 

[Michael A. Terrell]

Robert Baer wrote:

I see that one could *buy* small values of NPO caps speeced at 1%,
but according to the same data sheet, they can be as bad as 2.5% - which
appears to support my general statement.

Believe whatever you want, since you can't read the specs properly.

They were off the shelf or Microdyne would not have purchased them.
They were 1%, and the only bad ones I saw were physically damaged. The
were used in a Sallen Key low pass video filter with 14, 1% parts to
meet a 10% tolerance on the frequency spec. If the filter was slightly
out of tolerance I could usually swap the two caps and move it into spec
without changing the sets of restores. There was more problems with
slight variations of the inter layer capacitance of the PCB affecting
the filter. I tested and calibrated hundreds of these boards and I know
what parts I used.

--
Former professional electron wrangler.

Michael A. Terrell
Central Florida

 

[Michael Redmann]

EF schrieb:

Hi I'd appreciate some help.

I have a NiMh battery charger which has AC input of 100~120VAC
50~60HZ, 1.2A.

It outputs at 36VDC, 1.8A.

If I understand it correctly the charger has 1.2 A at 100 VAC (and maybe
1.0 A at 120 V). Here in Europe we often have wide range devices with
110...230 V input. The input current noted on the device nearly always
referes to the lowest input voltage.

So you need a transformer with output 100 V / 1.2 A with is 120 VA. You
don't need any additional wattage.

Regards
--
Michael Redmann
"It's life, Jim, but not as we know it." (Spock)

 

[CWatters]

"EF" <electronicfur@yahoo.co.uk> wrote in message
news:37e4eaf1.0504130232.44438c6d@posting.google.com...

Can we ask what it's for?

It's to charge a 36V 8Ah battery pack for an electric motor. I'm using
the motor on a bicycle.

Interesting. I was also going to ask if the battey is 3 lead acid cells in
series?. If so you might be able to rewire the batteries in parallel for
charging and use a 12V car battery charger.

If they aren't lead acid then the problem is harder. You can buy chargers
capable of charging 36V's worth of NiCad/HiMH cells (eg competition model
aircraft battery chargers) but they tend to be very expensive and most (all)
use a 12V battery as the power source to allow charging on the flying field.

 

[Don Bruder]

In article <d3so8q$hfr$1@reader01.singnet.com.sg>,
"Annie" <afritz@aol.com> wrote:

Hi, I just bought a portable handheld tv, the Casio TV-970, and want to
purchase a universal adaptor for it.
The universal adaptors I've seen have different ratings, from 350mA, to over
1000mA.
The specifications on the user guide says that it runs on 6 volts, and the
power consumption is approximately 3.1W.

How much mA do I need?

Regards,
Patrick

Watts = volts * amps, so 3.1 watts / 6 volts = 0.516 and change amps =
516 mA = round up to the next hundred to give you some "wiggle room",
and get a 6 volt, 600+ mA adapter (I'd expect that the closest
acceptable unit you'll find will be a 750 mA, although you might be able
to get your hands on a 600 mA version) and you're golden. The key is *AT
LEAST* the mA rating of the device. Anything less than the device's
rating, and you'll let all the magic smoke out of the adapter. More than
the device's rating will do no harm, but it won't do any good, either.
(beyond *MAYBE* extending the life of the adapter because it isn't
working "up against the redline" constantly.)

--
Don Bruder - dakidd@sonic.net - New Email policy in effect as of Feb. 21, 2004.
Short form: I'm trashing EVERY E-mail that doesn't contain a password in the
subject unless it comes from a "whitelisted" (pre-approved by me) address.
See <http://www.sonic.net/~dakidd/main/contact.html> for full details.

 

[Tom Biasi]

"mike" <spamme0@netscape.net> wrote in message
news:426225FE.9080202@netscape.net...

Then there's the size of the barrel connector. If it's just a little too
big, it can spring the contact so the thing won't run on batteries any
more. It's fun to go to Radio Shack and watch the "we got answers guy"
try to cram different sized connectors into the customer unit.

Also check to see if the unit requires center plus or center minus.
Tom

 

[Anno Siegel]

Tom Biasi <tombiasi@REMOVEoptonline.net> wrote in sci.electronics.misc:

"mike" <spamme0@netscape.net> wrote in message
news:426225FE.9080202@netscape.net...

Then there's the size of the barrel connector. If it's just a little too
big, it can spring the contact so the thing won't run on batteries any
more. It's fun to go to Radio Shack and watch the "we got answers guy"
try to cram different sized connectors into the customer unit.


Also check to see if the unit requires center plus or center minus.

Going off on a tangent here, but I have often wondered...

These devices usually have a diode in the supply line to protect
against inverted voltage. At the cost of three more diodes (and
another diode drop in the supply) one could put a bridge rectifier
there and never have to worry about polarity again. Is this
occasionally done? I've never seen it.

Anno

 

[Tom Biasi]

"Anno Siegel" <anno4000@lublin.zrz.tu-berlin.de> wrote in message
news:d42i7h$4hc$1@mamenchi.zrz.TU-Berlin.DE...

Tom Biasi <tombiasi@REMOVEoptonline.net> wrote in sci.electronics.misc:

"mike" <spamme0@netscape.net> wrote in message
news:426225FE.9080202@netscape.net...

Then there's the size of the barrel connector. If it's just a little
too
big, it can spring the contact so the thing won't run on batteries any
more. It's fun to go to Radio Shack and watch the "we got answers guy"
try to cram different sized connectors into the customer unit.


Also check to see if the unit requires center plus or center minus.

Going off on a tangent here, but I have often wondered...

These devices usually have a diode in the supply line to protect
against inverted voltage. At the cost of three more diodes (and
another diode drop in the supply) one could put a bridge rectifier
there and never have to worry about polarity again. Is this
occasionally done? I've never seen it.

Anno
Yes, I have seen it in a few (very few) products.

 

[Stewart Pinkerton]

On 19 Apr 2005 02:35:43 -0700, Winfield Hill
<hill_a@t_rowland-dotties-harvard-dot.s-edu> wrote:

Stewart Pinkerton wrote...

Rich Grise wrote:

Watson A.Name wrote:
... Last week I needed a 0.1 ohm resistor, ... so I measured 7.4
inches of #32 wire and wound it around a 1W high value resistor.
Now I only have the problem that it has 0.6 microhenry inductance.

Before winding it, bend the wire into a long, narrow "U" shape. Start
winding at the bend, in the middle of the form, and wind both ways. I
was told that this makes the inductances "cancel out". ;-)

Yes, it's known as bifilar winding, and would drop the above resistor
to less than a nanoHenry with reasonable care.

Not simply bifilar. The reversal scheme is called an Aryton-Perry
winding, e.g., as in Ohmite's WN series of wirewound non-inductive
resistors, http://www.ohmite.com/catalog/pdf/whm-wnm.pdf And etc.
It's also made by winding a layer in one direction, adding insulation
and winding the next layer back in the opposite direction, with the
turns crossing every 180 degrees.

An 'Ayrton Perry' winding *is* just a standard bifilar winding, most
easily made by cutting the length of wire you need, folding it in the
middle, and winding carefully from that midpoint to the ends, keeping
the twinned wire flat to ensure that adjacent turns always carry
opposing current.

--

Stewart Pinkerton | Music is Art - Audio is Engineering

 

[Winfield Hill]

Stewart Pinkerton wrote...

Not simply bifilar. The reversal scheme is called an Aryton-Perry
winding, e.g., as in Ohmite's WN series of wirewound non-inductive
resistors, http://www.ohmite.com/catalog/pdf/whm-wnm.pdf And etc.
It's also made by winding a layer in one direction, adding insulation
and winding the next layer back in the opposite direction, with the
turns crossing every 180 degrees.

An 'Ayrton Perry' winding *is* just a standard bifilar winding, most
easily made by cutting the length of wire you need, folding it in the
middle, and winding carefully from that midpoint to the ends, keeping
the twinned wire flat to ensure that adjacent turns always carry
opposing current.

Unless it's wound as I described above, which most machines seem
to do. The bifilar idea may be good for hand-made resistors, but
perhaps not for machines.

Also, a bifilar winding isn't necessarily a low-inductance winding,
that was my point. It may well be, if the end is connected, but
it wouldn't have to be. For example, for very low resistances
multiple parallel wires are helpful, wound all at once and shorted.


--
Thanks,
- Win

 

[Rich Grise]

On Tue, 19 Apr 2005 11:34:55 -0700, Winfield Hill wrote:

Stewart Pinkerton wrote...

Not simply bifilar. The reversal scheme is called an Aryton-Perry
winding, e.g., as in Ohmite's WN series of wirewound non-inductive
resistors, http://www.ohmite.com/catalog/pdf/whm-wnm.pdf And etc.
It's also made by winding a layer in one direction, adding insulation
and winding the next layer back in the opposite direction, with the
turns crossing every 180 degrees.

An 'Ayrton Perry' winding *is* just a standard bifilar winding, most
easily made by cutting the length of wire you need, folding it in the
middle, and winding carefully from that midpoint to the ends, keeping
the twinned wire flat to ensure that adjacent turns always carry
opposing current.

Unless it's wound as I described above, which most machines seem
to do. The bifilar idea may be good for hand-made resistors, but
perhaps not for machines.

Also, a bifilar winding isn't necessarily a low-inductance winding,
that was my point. It may well be, if the end is connected, but
it wouldn't have to be. For example, for very low resistances
multiple parallel wires are helpful, wound all at once and shorted.

Bifilar means to me that the wires stay parallel throughout:

Loop
^
\\ \\ \\ \\ \\_
\_ Leads

But the one I had in mind was more like this:
Loop
^
Lead _/ / / / \ \ \ \_ Lead

I don't know what it's called.

Cheers!
Rich

 

[tim gorman]

Dan Piponi wrote:

I'm doing some stuff with a 2x16 HD44780 display. Most things seem to
work fine. I can clear the screen, reset the cursor to the top left,
write characters, set the thing to scroll mode and so on.

But one thing always fails: set the cursor to the start of the second
row. This is supposed to be instruction 0xc0(=0x80+0x40 for 2nd row).
Instead it either does nothing or outputs a space. I don't think it's a
timing issue: my timing loops seem to work fine for other instructions.
Has anyone else seen this problem?

Is there some precondition I need to set before I can start setting the
cursor position - something I need to do during initialisation?

Thanks...

If you can display char's and everything I don't the timing is the problem.

Are you sure the LCD is good? Do you have a spare you could try? Be a real
irritation to find out the LCD has a bad char in the second row, 1st
position!

Tim

 

[ehsjr]

Rich Grise wrote:

On Tue, 19 Apr 2005 11:34:55 -0700, Winfield Hill wrote:


Stewart Pinkerton wrote...

Not simply bifilar. The reversal scheme is called an Aryton-Perry
winding, e.g., as in Ohmite's WN series of wirewound non-inductive
resistors, http://www.ohmite.com/catalog/pdf/whm-wnm.pdf And etc.
It's also made by winding a layer in one direction, adding insulation
and winding the next layer back in the opposite direction, with the
turns crossing every 180 degrees.

An 'Ayrton Perry' winding *is* just a standard bifilar winding, most
easily made by cutting the length of wire you need, folding it in the
middle, and winding carefully from that midpoint to the ends, keeping
the twinned wire flat to ensure that adjacent turns always carry
opposing current.

Unless it's wound as I described above, which most machines seem
to do. The bifilar idea may be good for hand-made resistors, but
perhaps not for machines.

Also, a bifilar winding isn't necessarily a low-inductance winding,
that was my point. It may well be, if the end is connected, but
it wouldn't have to be. For example, for very low resistances
multiple parallel wires are helpful, wound all at once and shorted.


Bifilar means to me that the wires stay parallel throughout:

Loop
^
\\ \\ \\ \\ \\_
\_ Leads

But the one I had in mind was more like this:
Loop
^
Lead _/ / / / \ \ \ \_ Lead

I don't know what it's called.

Cheers!
Rich

That's it, exactly. Someone called it "contra-wound" -

but I don't know if that is the proper term. On the toroids
I wind that way, the first half occupies about 40% of
the diameter and the last half occupies another 40%.
Ed

 

[Watson A.Name - \"Watt Su]

"ehsjr" <ehsjr@bellatlantic.net> wrote in message
news:aYj9e.75561$B12.18121@trnddc09...

Rich Grise wrote:
[snip]

Bifilar means to me that the wires stay parallel throughout:

Loop
^
\\ \\ \\ \\ \\_
\_ Leads

But the one I had in mind was more like this:
Loop
^
Lead _/ / / / \ \ \ \_ Lead

I don't know what it's called.

Cheers!
Rich

That's it, exactly. Someone called it "contra-wound" -
but I don't know if that is the proper term. On the toroids
I wind that way, the first half occupies about 40% of
the diameter and the last half occupies another 40%.
Ed

I'm just curious as to why you'd want to use a toroid. The whole idea
of a toroid is to increase the magnetic field containment, so you get
better inductance. Then you go winding it bifilar, to _get_rid_ of the
inductance! This doesn't make sense.

Oh, one other point. This "contra-wound" method can only be used for a
single layer. Anf it looks like the winding has to start at the hairpin
bend of hte halfway point and go outward.

 

[Winfield Hill]

Rich Grise wrote...

Winfield Hill wrote:

Also, a bifilar winding isn't necessarily a low-inductance winding,
that was my point. It may well be, if the end is connected, but
it wouldn't have to be. For example, for very low resistances
multiple parallel wires are helpful, wound all at once and shorted.

Bifilar means to me that the wires stay parallel throughout:

Loop
^
\\ \\ \\ \\ \\_
\_ Leads

Indeed, but my point was that the word "bifilar" does not by itself
imply low inductance, as the bifilar construction below illustrates.

.. ---,
.. ^
.. \\ \\ \\ \\ \\
.. V
.. '---


--
Thanks,
- Win

 

[Rich Grise]

On Wed, 20 Apr 2005 04:23:32 -0700, Watson A.Name - "Watt Sun, the Dark
Remover" wrote:

On Wed, 20 Apr 2005 04:23:32 -0700, Watson A.Name - "Watt Sun, the Dark

"ehsjr" <ehsjr@bellatlantic.net> wrote in message
Rich Grise wrote:
[snip]

Bifilar means to me that the wires stay parallel throughout:

Loop
^
\\ \\ \\ \\ \\_
\_ Leads

But the one I had in mind was more like this:
Loop
^
Lead _/ / / / \ \ \ \_ Lead

I don't know what it's called.

Cheers!
Rich

That's it, exactly. Someone called it "contra-wound" -
but I don't know if that is the proper term. On the toroids
I wind that way, the first half occupies about 40% of
the diameter and the last half occupies another 40%.
Ed

I'm just curious as to why you'd want to use a toroid. The whole idea
of a toroid is to increase the magnetic field containment, so you get
better inductance. Then you go winding it bifilar, to _get_rid_ of the
inductance! This doesn't make sense.

Oh, one other point. This "contra-wound" method can only be used for a
single layer. Anf it looks like the winding has to start at the hairpin
bend of hte halfway point and go outward.

Yes, that's exactly it. I saw it in a book once.

Cheers!
Rich

 

[Dennis]

Dan Piponi wrote:

I know the LCD itself is good as I now have a workaround: I notice that
if you print 40 characters on the first line you wrap and start on the
second row. So I can get to the second row by sending 24 padding
characters after filling row 1. Not entirely satisfactory but it'll
have to do. Seems bizarre I can get every function to work but one! I
did have a hunch that maybe I was accidentally masking the top bit of
the instruction in my code (as every other instruction I use <0x80) but
after checking my code I don't think that's it.
--
Dan

Did you init it to 2 line mode when you set it up? If you don't do a
Function Set command the default is 8 bit interface, 1 line, 5x8
characters. Single line mode is 80 bytes linear addressing. Two line
mode splits the addressing to line 1 at offset 0, and line 2 starting at
offset x'40'

 

[ehsjr]

Watson A.Name - "Watt Sun, the Dark Remover" wrote:

"ehsjr" <ehsjr@bellatlantic.net> wrote in message
news:aYj9e.75561$B12.18121@trnddc09...

Rich Grise wrote:

[snip]


Bifilar means to me that the wires stay parallel throughout:

Loop
^
\\ \\ \\ \\ \\_
\_ Leads

But the one I had in mind was more like this:
Loop
^
Lead _/ / / / \ \ \ \_ Lead

I don't know what it's called.

Cheers!
Rich


That's it, exactly. Someone called it "contra-wound" -
but I don't know if that is the proper term. On the toroids
I wind that way, the first half occupies about 40% of
the diameter and the last half occupies another 40%.
Ed


I'm just curious as to why you'd want to use a toroid. The whole idea
of a toroid is to increase the magnetic field containment, so you get
better inductance. Then you go winding it bifilar, to _get_rid_ of the
inductance! This doesn't make sense.
First, it is not bifilar. Picture a center tapped coil wound

single layer on a toroid. It is that, except that the second
half is wound in the opposite direction.

And it makes sense. I'll try a diagram.

+------+-----------------+
| | |
| Mosfet |
___ | B
___ +------|<----+ A
| ( | T
| ( L1 | T
| ( | E
+------+ | R
) | Y
) L2 | |
) | |
-----------+------------+----+

L2 isolates the bottom of L1 from the negative rail
on the discharge part of the cycle. On the charge part,
the Xl's cancel out, leaving only the winding R in the
charge path. That allows reduction of the charge time.

Ed

Oh, one other point. This "contra-wound" method can only be used for a
single layer. Anf it looks like the winding has to start at the hairpin
bend of hte halfway point and go outward.

 

[Tom Biasi]

"twags6" <twags6@hotmail.com> wrote in message
news:1114067393.254900.126750@f14g2000cwb.googlegroups.com...

Is there any way to make a dc power supply capable of 50+ amps at
12-13.8 vdc? Basically, I'm looking for something to simulate the
power from a car without the whole battery and charger setup. Parts
express sells a nice rackmount one, but I'd rather not part with $190.

TIA

Trevor

Hi Trevor,
What is the application for this supply?
If you need nice clean regulated power you can spend more than the $190.00
that you quoted.
When I worked on high current mobile transceivers I would use the battery
and charger set up, best power for the money.
Regards,
Tom

 

[Fester Addams]

"OLY" <Gyruss1984@yahoo.com> wrote in message
news:1113855675.922188.241210@z14g2000cwz.googlegroups.com...

Ends Tonight

Metcal- nice, but not THAT nice for just a soldering iron.