EDAboard.com | EDAboard.eu | EDAboard.de | EDAboard.co.uk | RTV forum PL | NewsGroups PL

magnetic field

Ask a question - edaboard.com

elektroda.net NewsGroups Forum Index - Electronics Others - magnetic field

Goto page Previous  1, 2, 3 ... 205, 206, 207, 208  Next

Michael A. Terrell
Guest

Thu Jan 30, 2014 8:31 am   



Jeff Thies wrote:
Quote:

On 1/26/2014 11:35 AM, Fred Abse wrote:
On Sun, 26 Jan 2014 08:13:56 -0500, Jim Wilkins wrote:

"DoN. Nichols" <BPdnicholsBP_at_d-and-d.com> wrote in message
news:slrnle97cu.5kc.BPdnicholsBP_at_Katana.d-and-d.com...
On 2014-01-25, Jim Wilkins <muratlanne_at_gmail.com> wrote:

Why do you need two fuses for a single-phase motor?

In the UK, you don't, because 240 VAC comes with one side grounded.
However, in the USA, 240 VAC is normally supplied with a grounded center
tap, so if you have only one fuse -- or have two but only one blows, you
still have 120 VAC live in the motor's housing, and
potentially available for contact and personal zapping. :-)


I assumed it was wired with a 20A double-pole breaker at the panel
protecting from shorts and a smaller fuse sized (how?) to blow before the
motor burned out.


Panel breakers are there to protect the upstream wiring from excessive
load current, not to protect the load.

Matching the I-squared-t of a breaker, or fuse, to startup and running
conditions of a motor is not trivial. Motors are subject to starting
inrush currents sometimes tens of times the rated full-load current. Be
guided by the data published by reputable manufacturers. There's plenty of
it.

Most motors are tough old buzzards. Why the op needs more protection is
unknown, I would think some kind of thermal or time delay overload is
sufficient which may already be in the motor.


I got this in an email from someone who wasn't able to post directly:

<http://www.ab.com/en/epub/catalogs/12768/229240/229248/10521726/10551021/10551660/>

Obviously, I can't post to the newsgroup.

Jeff Angus

Peter Bennett
Guest

Sun Mar 23, 2014 5:16 am   



On Sat, 22 Mar 2014 11:09:39 -0700, DaveC <invalid_at_invalid.net> wrote:

Quote:
Looking for the manufacturer and (praying) the series of this connector:

http://oi57.tinypic.com/w7luea.jpg

http://oi57.tinypic.com/2hylbub.jpg

It is not proprietaryőit was used to connect 2 old pieces of equipment much
older than this connector.á

Ideas?

Thanks.


Cinch Jones Plug - available from Mouser, made by www.cinch.com

--
Peter Bennett, VE7CEI Vancouver BC
peterbb (at) telus.net
Vancouver Power Squadron: http://vancouver.powersquadron.ca


Guest

Tue Apr 22, 2014 6:57 am   



On Sunday, February 14, 1999 3:00:00 AM UTC-5, EW_Chua wrote:
Quote:
BGA Automatic Pick and Place System.

We are in urgent need for the above system.
It is used to sort BGA packages from film frames to an output carrier, The
machine must includes an automatic cassette feed system, rotating pick head,
and pattern recognition alignment on the input and output stations.
We are willing to buy new or used.

For more details or submission of proposal, please contact :

KH Lee
Tel:65-7511128 / Fax:65-7555387
Email: kahheng_at_stats.st.com.sg
EW Chua
Tel:65-7511126 / Fax:65-7555387
Email: chuaew_at_stats.st.com.sg


Contact me and I'll get it for you.
Visit www.advancedreworks.com

Geo
Guest

Tue Apr 22, 2014 8:26 pm   



On Mon, 21 Apr 2014 21:57:43 -0700 (PDT), drichiez_at_hotmail.com wrote:

Quote:
On Sunday, February 14, 1999 3:00:00 AM UTC-5, EW_Chua wrote:
BGA Automatic Pick and Place System.

We are in urgent need for the above system.

Contact me and I'll get it for you.
Visit some spammer's website


It was URGENT in 1999 you twat!

conundrum
Guest

Sat May 31, 2014 8:21 am   



On Wednesday, May 28, 2014 9:54:44 PM UTC+1, Gary Walters wrote:
Quote:
Crest model 4G-250-3, early 90's vintage.



Part numbers have been sanded off all ICs.



It would be great to find a schematic...



Thanks.


High frequency op amp most likely.

IIRC the ultrasonic foggers use 1.67 MHz and the smaller ones use around 30-40 kHz (thanks Sam!) but 67kHz is becoming popular as it is less likely to interfere with other devices and is more effective for cleaning.

Don Kelly
Guest

Tue Jul 15, 2014 7:32 am   



On 14/07/2014 3:40 PM, Dan Coby wrote:
Quote:
On 7/14/2014 9:00 AM, DaveC wrote:
I need to provide jog function on a machine (run the motor for a few
seconds
under load) without use of VFD**. It was done on this small printing
press
with a 3 HP, 3-phase motor but the customer has no multiphase power so
I┬╣m
changing to a 220 ┬│single phase┬▓ 5 HP motor.

Is there any inherent issue with starting an asynchronous motor under
load? A
3ph motor does this with ease, but can the same be said of an async
motor?
Should I be looking at a particular design of async motor?

Also, reversing an asynch motor┬őis this a straightforward thing to do?
I'm
thinking about bringing the directional wiring inside the motor's
terminal
box out to separate contactors. I'm also thinking about
cross-connecting aux
contacts in the contactors to eliminate possibility of actuating both
simultaneously and some kind of timer relay to provide delay between
forward
and reverse actuation.

Any observations or experience you┬╣d like to share would be greatly
appreciated.

Thanks!


** The customer has said ┬│absolutely no VFD┬▓. Apparently his business
neighbor has had nothing but troubles with VFDs (blowing the supply
fuses;
smoking at least one VFD) and he is terrified of them. It┬╣s an emotional
issue, not a logical one so no amount of discussion can change his mind.
We┬╣ve tried.


Does your customer have any objection to a non-electronic converter? A
common means of running 3 phase motors from a single phase supply is via
the use of rotary phase converters.

http://en.wikipedia.org/wiki/Rotary_phase_converter


Dan

Such rotary phase converters have been commonly used in the past and can
be cobbled together from surplus equipment such as a 5-7.5HP 3 phase
motor driven by a single phase motor <1HP at an estimate.
I should think that this is the cheapest alternative.
It is bulky but it means that the original 3 phase 3HP potor can be
kept. Capacitors can help.

However, the sizing of the original motor is probably based on the load
current at start -and a HP rating to fit this and also fit an rms HP
limit equivalent. It may be that a 3HP single phase motor -capacitor
start designed for max torque near standstill would do the job as the
duty cycle is the same as before.
Check the specific info for the original motor and a replacement. The
single phase replacement will be expensive and there would likely be
mounting problems.
It's a bit of a toss up- mainly economics
--

Don Kelly
remove the cross to reply


Guest

Tue Jul 15, 2014 12:11 pm   



On Mon, 14 Jul 2014 09:00:10 -0700, DaveC <invalid_at_invalid.net> wrote:

Quote:
I need to provide jog function on a machine (run the motor for a few seconds
under load) without use of VFD**. It was done on this small printing press
with a 3 HP, 3-phase motor but the customer has no multiphase power so I╣m
changing to a 220 │single phase▓ 5 HP motor.


The classical trick running an existing three phase motor from a
single phase supply is to connect capacitors between the three motor
terminals and then connect the single phase source between two of the
terminals.

Of course, the voltage is now lower, so less power is available.
Perhaps a autotransformer could be used to beef up the voltage. Having
intermediate taps in the autotransformer could be used to alter
starter or tongue performance.

josephkk
Guest

Fri Jul 18, 2014 8:07 am   



On Tue, 15 Jul 2014 21:48:50 -0700, DaveC <invalid_at_invalid.net> wrote:

Quote:
However, in this case of a jog function- If a single phase capacitor
start single phase motor has the same starting torque as the 3 phase
motor (and with the right capacitor- this may well be done) a single
phase motor may well fit the needs-electrically-but likely not
mechanically with respect to mounting.

I (OP) am concerned about jogging. The single-phase motor will be using its
start winding, and the associated high current will heat the winding. Jogging
means usually repeated, sometimes back-and-forward direction changes, short
motor actuations.

With all this jogging the centrifugal start switch will be abused over time
which probably means early failure.


Two easy answers:
a. use a cap run motor
b. use a current sensing start switch

Also this will almost always be within the start time of the jogger motor.

?-)

Ian Field
Guest

Fri Aug 01, 2014 2:24 am   



"Pavel Svinchnik" <pintiha_at_jhmi.edu> wrote in message
news:f29c85c2-65e1-401a-947d-2332e168fed3_at_googlegroups.com...
Quote:
I need some sort of device to equalize the volume of audio feed to my TV
but don't know what it's called or even if there is such a thing. I have a
fairly new flat screen TV which is fed by several devices; cable box,
BluRay, an old VHS/DVD player, and X-Box.

The problem is that for the BluRay, I have to turn the volume on the TV up
to 90 or above to hear it, while the cable box is deafening anywhere above
25. The problem is that if my wife has been watching something on the
BluRay and I turn on the TV to cable, it's horribly loud until I can hit
mute or turn down the sound. It seems that there should be something
available to buffer the inputs from the various devices and send the audio
signal to the TV at a consistent volume.


Maybe the cheapest option is to route everything through a compressor.

Basically a variable gain amplifier, the incoming audio is sampled to
produce a control voltage for the VGA.


Guest

Tue Aug 19, 2014 7:20 pm   



On Wednesday, November 6, 2002 5:39:22 PM UTC-8, Robert Hawk wrote:
Quote:
RATELCO Battery charger / Rectifier. Type FC481505A Model #
102B-3608-00. 48 Volt @ 150 Amps, Float or Equalize. These units were
manufactured SEPT 1991 and are in the Factory crates and have Never
been used, have 2, sequential Serial numbers. These units can be used
as 48 volt charger for Telephone Central Office Battery supply's with
the ability to Float or Equalize. They can also be used as a stand
alone, well filtered, power supply rated at 48 volts at 150 amps
CONTINOUS DUTY. Input = 110, 208, 240 Volts. 60 Hz, single phase A
must for the expirimenter working with the new generation of 48 volt
solid state RF devices Rated in excess of a Kilowatt. Weight is
approximately 550 pounds, Crated for freight shipping. $1500.xx
Prepaid, in my garage. Loading and shiping are buyers responsibility.

Pictures can be seen at

http://gnc.net/~rhawk/index.html

Bob


Bob , where are you located , and what is your current asking price . Boyd


Guest

Thu Sep 11, 2014 7:51 pm   



Hey, you can use WP Profit Builder to create a new website only Drag and Drop. it launch at 16/09/2014. you can find more informations about it in video: https://www.youtube.com/watch?v=rEX7UDrZSvU


Guest

Thu Sep 11, 2014 7:52 pm   



Hey, you can use WP Profit Builder to create a new website only Drag and Drop. it launch at 16/09/2014. you can find more informations about it in video:

https://www.youtube.com/watch?v=rEX7UDrZSvU


Guest

Thu Sep 11, 2014 7:53 pm   



Hey, you can use WP Profit Builder to create a new website only Drag and Drop. it launch at 16/09/2014. you can find more informations about it in video:

https://www.youtube.com/watch?v=rEX7UDrZSvU


Guest

Sat Oct 25, 2014 5:07 pm   



On Friday, October 17, 2014 1:57:54 PM UTC+1, DaveC wrote:
Quote:
I have a 12V SPST cube relay in my junque box. The diagram molded into the
relay╣s housing includes a component connected in parallel with the coil
which looks suspiciously like a resistor.

It╣s not a back-emf diode: I connected the relay coil using both polarities
(using a current-limited power supply) and the same current draw is measured.


What is the purpose of this resistor?

Thanks,
Dave


The resistor is there to dampen back emf. I've come across them in Hella/Bosch sales catalogues. Use with ecu if more normal damper diode is not already fitted/contained in ecu. An application is early fuel injection systems fitted to older Volkswagen Varient models.


Guest

Tue Oct 28, 2014 4:34 am   



I know this is a really old thread, I found one of the radios also. Is it still running? And how did the bulb replacement go? Also I have a loose wire that goes up to the doze button can't find what spot on the board it suppose to connect to. It is loose right under the fiber board. I think I see where it once was but not sure.


On Sunday, January 9, 2005 8:34:38 PM UTC-5, Bob Archambault wrote:
Quote:
boba3_at_earthlink.net wrote:

I am in the process of repairing a 1970's clock radio:

Panasonic RC-7462

The radio plays perfectly, and I was able to repair the clock. All
that it needs now is to have the clock lamp replaced. This is a
strange lamp in that it is a tube which is 3 1/4" inches long and
5/16" in diameter, and is soldered direct to its wires (which are both
on one end of the tube). It appears to be a neon or fluorescent type of tube.
It is supplied with 230 volts AC to operate it. I have taken the following numbers
off of the tube (which I hope are correct, since these numbers are almost
microscopic, and I have MUCH trouble seeing them, but here goes...):

NL 60T8-B

Can some one please tell me:

A) What type of lamp this is? -and-

B) Where can I obtain a replacement?


All replies, with the exception of the smart-alecky "throw the POS away
and get a new radio" types, would be greatly appreciated!


OK, folks...

I just want to end this thread and let everyone know how I made out.
I used the green neon bulb from Radio Shack (# 272-708) and cut the
plastic housing away from the bulb with my Dremel tool. While it is
certainly not original, it works just fine and looks pretty good as well.

As far as the original bulb - the NL 60T8-B, I did some experimentation
and determined that it is absolutely a colored neon bulb that gives off
a light purplish-blue color. I found this out by using a microwave to exite
the phosphor coating, thereby letting it show its true colors <g>. My feelings
about the bulb number are pretty much:

NL = Neon Lamp
T8 = Tubular, 8mm diameter
B = Blue

Now as far as the "60" goes, I'm not really sure. Franc suggested the
possibility of it being the striking voltage. I tend to think not, as it would
seem that you wouldn't need 230 V to run a tube that only needs 60 V to
start. I don't think it's a wattage rating, as this certainly seems more powerful
than 60 mW, but is less than 6.0 W. I did notice that the phosphor coating
(which corresponds exactly to the lighted area) is precisely 60mm long,
so that's a possibility. But, again, I really don't know.

In any case, I want to thank all of you who contributed thoughts and
suggestions. I learned a little, and most importantly, repaired the
item satisfactorily.

A final thought - I am still not averse to restoring this to its original
condition, so if someone, at some later time, ambles across this
thread and has first-hand knowledge of where I might actually find
a good NL60T8-B, please e-mail me at:

boba3_at_earthlink.net


Thanks very much...

Bob Archambault


Goto page Previous  1, 2, 3 ... 205, 206, 207, 208  Next

elektroda.net NewsGroups Forum Index - Electronics Others - magnetic field

Ask a question - edaboard.com

Arabic versionBulgarian versionCatalan versionCzech versionDanish versionGerman versionGreek versionEnglish versionSpanish versionFinnish versionFrench versionHindi versionCroatian versionIndonesian versionItalian versionHebrew versionJapanese versionKorean versionLithuanian versionLatvian versionDutch versionNorwegian versionPolish versionPortuguese versionRomanian versionRussian versionSlovak versionSlovenian versionSerbian versionSwedish versionTagalog versionUkrainian versionVietnamese versionChinese version
RTV map EDAboard.com map News map EDAboard.eu map EDAboard.de map EDAboard.co.uk map