sci.electronics.repair - 25 new messages in 9 topics - digest

sci.electronics.repair
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Today's topics:

==============================================================================
TOPIC: Microwave oven diode bad?
http://groups.google.com/group/sci.electronics.repair/t/68504020f6b6237b?hl=en
==============================================================================

== 1 of 1 ==
Date: Mon, Aug 29 2011 11:43 pm
From: "Michael A. Terrell"

JeffM wrote:
>
> >Spamm Trappe wrote:
> >>Since there obviously lacking, their ought to be continuing education
> >>classes where illiterates can improve they're language skills.
> >>
> Michael A. Terrell wrote:
> >Since you want to point out typos, it's 'their language skills',
> >jackass.
> >
> Interesting that you dindn't mention the other 2
> purposeful misuses among there/their/they're
> Satire is wasted on some people.

One was enough. I made my mistakes from not enough sleep, for
months. Some days I'm in so much pain that I just don't give a damn.
Neither does my VA doctor, who thinks that the medication for diabetic
neuropathy is a real pain killer. He informed me that I was already on
'A very high dosage of pain killers'.

--
You can't have a sense of humor, if you have no sense.

==============================================================================
TOPIC: Motor start/stop switch with integrated mini contactor?
http://groups.google.com/group/sci.electronics.repair/t/13b233689d902984?hl=en
==============================================================================

== 1 of 4 ==
Date: Tues, Aug 30 2011 2:20 am
From: The Ghost In The Machine

On Aug 30, 1:59 am, DaveC <inva...@invalid.net> wrote:
> > Harbor Freight, or any number of other machine importers/sellers could
> > probably supply a switch of this type.
> > The parts lists are available from at least a couple of said companies.
>
> I've searched for "No-Volt Release" (NVR) switches and have found very, very
> few here in N. America. The US definition is a full contactor inside a
> housing with a start/stop combo switch on the front. Not my idea of "min".
>
> Europe uses these much more.
>
> HF doesn't list anything like this.
>
> If you know of any manufacturers I'd be glad to know of them.
>
> SNIP/

YOU MUST THINK YOU'RE DEALING WITH SOME KIND OF DUMMIES.

"TELEMECANIQUE" HAS THEM......NOW OWNED BY SCHNEIDER ELECTRIC.

PATECUM
TGITM

== 2 of 4 ==
Date: Tues, Aug 30 2011 11:48 am
From: DaveC

> TELEMECANIQUE

Can you please give me p/n or link? I've not turned up any yet.

Maybe I'm the dummy...

Thanks,
Dave

== 3 of 4 ==
Date: Tues, Aug 30 2011 12:18 pm
From: DaveC

The only Telemecanique products I've been able to find are full-size magnetic
starters (contactors).

I'm looking for a manual start/stop switch with 2-pole contactor built-in.
Pressing the start button manually closes the contacts and energizes a coil,
which holds the contacts closed. Power fail opens the contacts.

Small (micro!) is what I'm looking for. No larger than the size of a
start/stop switch without contactor.

Dave

== 4 of 4 ==
Date: Tues, Aug 30 2011 1:03 pm
From: "krw@att.bizzzzzzzzzzzz"

On Tue, 30 Aug 2011 12:18:02 -0700, DaveC <invalid@invalid.net> wrote:

>The only Telemecanique products I've been able to find are full-size magnetic
>starters (contactors).

Ignore the troll.

>I'm looking for a manual start/stop switch with 2-pole contactor built-in.
>Pressing the start button manually closes the contacts and energizes a coil,
>which holds the contacts closed. Power fail opens the contacts.
>
>Small (micro!) is what I'm looking for. No larger than the size of a
>start/stop switch without contactor.

These are sometimes called "magnetic start switches" and are commonly found on
larger woodworking tools. I don't know if they're small enough for you but:
http://www.grizzly.com/search/search.aspx?q=power%20switch

==============================================================================
TOPIC: Contactor coil: 50 Hz vs. 60 Hz
http://groups.google.com/group/sci.electronics.repair/t/0d1a06068779ce43?hl=en
==============================================================================

== 1 of 10 ==
Date: Tues, Aug 30 2011 2:47 am
From: John Fields

On Tue, 30 Aug 2011 02:58:19 +0000 (UTC), David Lesher
<wb8foz@panix.com> wrote:

>John Fields <jfields@austininstruments.com> writes:
>
>
>>I have an old P&B MR5A here with a 240V 50/60Hz coil.
>
>>The coil has a resistance of 4800 ohms, and an open inductance of 14.5
>>henrys, so it has an impedance of 6616 ohms at 50 Hz, and 7270 ohms at
>>60 Hz.
>
>What's the inductance while closed?

---
16 henries, but that measurement was made by closing the armature
manually.

If there's any real interest I can measure it energized.

--
JF

== 2 of 10 ==
Date: Tues, Aug 30 2011 4:39 am
From: John Fields

On Mon, 29 Aug 2011 07:25:23 -0700 (PDT), NT <meow2222@care2.com>
wrote:

>IME relays pull in at in the region of half rated voltage, and dc
>ratings are typically about half the voltage of the ac rating, which
>gives an idea of how much current is determined by L and how much by
>R.

---
IME, most relays (with either AC or DC coils) are guaranteed to pull
in at about 80% of their rated coil voltage, so I'm at a loss trying
to understand what you meant by: "dc ratings are typically about half
of the ac rating."

Can you elaborate, please?
---

>Running your relay on 220v 60Hz it will work fine.

---
Knowing nothing about the contactor, other than that it's specified to
energize when 240V 50Hz is placed across the coil, your imprimatur is
premature.
---

>Contact closing speed will be slightly slower. Margin will be reduced,
>but its only being reduced from enormous to slightly less enormous,
>so its a non-issue except in very unusual situations.

---
It seems you've forgotten that when the armature makes, and the
magnetic circuit is closed, the inductance of the coil will rise.

Such being the case, the current in it will diminish, reducing the
hold on the armature and making the contacts more likely to chatter.
---

>The vibration tolerance of
>the contacts will be little affected in practice; if your environment
>is harsh enough to shake the relay contact open, then you've got
>bigger worries than contacts crackling.

>If instead you meant you would use it on 110v 60Hz, then dont. But you
>could use diodes to get a higher dc voltage and use that.

---
Interesting conjecture.

Something like this?

+-----+
120AC>--|~ +|----+
| | |
| | [COIL]
| | |
120AC>--|~ -|----+
+-----+

Since the coil has an impedance of about 6600 ohms at 50Hz, then the
current through it will be:

E 240V
I = --- = ------- = 0.036A = 36mA
Z 6600R

Then, since the coil has a resistance of 4800 ohms, the DC voltage
across it required to force 36mA through it would be:

E = IR = 0.036A * 4800R ~ 174V.

The peak voltage out of the bridge would be:

E = RMS * sqrt(2) = 120 * 1.414 ~ 170V.

Pretty close, but at 120Hz, the reactance of the coil would increase,
limiting the current to something less than the 36mA needed to close
the armature.

However, the reactance of the coil will smooth the current and the
addition of a capacitor in parallel with the coil will remove some of
the ripple and allow the coil to see more nearly pure DC.

Here's a simulation showing both ways:

Version 4
SHEET 1 880 680
WIRE -144 16 -304 16
WIRE 112 16 -144 16
WIRE 448 16 288 16
WIRE 704 16 448 16
WIRE -304 80 -304 16
WIRE 288 80 288 16
WIRE 448 80 448 64
WIRE 480 80 448 80
WIRE 592 80 560 80
WIRE 704 80 704 64
WIRE 704 80 672 80
WIRE -144 112 -144 80
WIRE -112 112 -144 112
WIRE 0 112 -32 112
WIRE 112 112 112 80
WIRE 112 112 80 112
WIRE -144 160 -144 112
WIRE 112 160 112 112
WIRE 448 160 448 80
WIRE 544 160 448 160
WIRE 704 160 704 80
WIRE 704 160 608 160
WIRE -304 224 -304 160
WIRE -144 224 -304 224
WIRE 112 224 -144 224
WIRE 288 224 288 160
WIRE 448 224 288 224
WIRE 704 224 448 224
WIRE -304 272 -304 224
WIRE 288 272 288 224
FLAG -304 272 0
FLAG 288 272 0
SYMBOL ind -128 128 R270
WINDOW 0 32 56 VTop 0
WINDOW 3 5 56 VBottom 0
SYMATTR InstName L1
SYMATTR Value 15
SYMBOL voltage -304 64 R0
WINDOW 3 24 104 Invisible 0
WINDOW 123 0 0 Left 0
WINDOW 39 0 0 Left 0
SYMATTR InstName V1
SYMATTR Value SINE(0 170 60)
SYMBOL diode -160 16 R0
WINDOW 0 4 -52 Left 0
WINDOW 3 -28 -24 Left 0
SYMATTR InstName D1
SYMATTR Value MUR460
SYMBOL diode 128 80 R180
WINDOW 0 1 119 Left 0
WINDOW 3 -33 84 Left 0
SYMATTR InstName D2
SYMATTR Value MUR460
SYMBOL diode 96 160 R0
WINDOW 0 3 89 Left 0
WINDOW 3 -27 118 Left 0
SYMATTR InstName D3
SYMATTR Value MUR460
SYMBOL diode -128 224 R180
WINDOW 0 2 -28 Left 0
WINDOW 3 -31 -57 Left 0
SYMATTR InstName D4
SYMATTR Value MUR460
SYMBOL res -16 128 R270
WINDOW 0 32 56 VTop 0
WINDOW 3 0 56 VBottom 0
SYMATTR InstName R1
SYMATTR Value 4800
SYMBOL ind 464 96 R270
WINDOW 0 32 56 VTop 0
WINDOW 3 5 56 VBottom 0
SYMATTR InstName L2
SYMATTR Value 15
SYMBOL voltage 288 64 R0
WINDOW 3 24 104 Invisible 0
WINDOW 123 0 0 Left 0
WINDOW 39 0 0 Left 0
SYMATTR InstName V2
SYMATTR Value SINE(0 170 60)
SYMBOL diode 432 16 R0
WINDOW 0 4 -52 Left 0
WINDOW 3 -28 -24 Left 0
SYMATTR InstName D5
SYMATTR Value MUR460
SYMBOL diode 720 80 R180
WINDOW 0 1 119 Left 0
WINDOW 3 -33 84 Left 0
SYMATTR InstName D6
SYMATTR Value MUR460
SYMBOL diode 688 160 R0
WINDOW 0 3 89 Left 0
WINDOW 3 -27 118 Left 0
SYMATTR InstName D7
SYMATTR Value MUR460
SYMBOL diode 464 224 R180
WINDOW 0 2 -28 Left 0
WINDOW 3 -31 -57 Left 0
SYMATTR InstName D8
SYMATTR Value MUR460
SYMBOL res 576 96 R270
WINDOW 0 32 56 VTop 0
WINDOW 3 0 56 VBottom 0
SYMATTR InstName R2
SYMATTR Value 4800
SYMBOL cap 608 144 R90
WINDOW 0 0 32 VBottom 0
WINDOW 3 32 32 VTop 0
SYMATTR InstName C1
SYMATTR Value 10µ
TEXT -298 246 Left 0 !.tran .05

If the relay is spec'ed as "must make" at 80% of rated current through
the coil (~29mA), then note that with a 10µF cap in parallel with the
coil the relay will _always_ make using full-wave rectified 120V 60Hz
mains.

--
JF

== 3 of 10 ==
Date: Tues, Aug 30 2011 5:11 am
From: NT

On Aug 30, 12:39 pm, John Fields <jfie...@austininstruments.com>
wrote:
> On Mon, 29 Aug 2011 07:25:23 -0700 (PDT), NT <meow2...@care2.com>
> wrote:
>
> >IME relays pull in at in the region of half rated voltage, and dc
> >ratings are typically about half the voltage of the ac rating, which
> >gives an idea of how much current is determined by L and how much by
> >R.
>
> ---
> IME, most relays (with either AC or DC coils) are guaranteed to pull
> in at about 80% of their rated coil voltage, so I'm at a loss trying
> to understand what you meant by: "dc ratings are typically about half
> of the ac rating."
>
> Can you elaborate, please?

When relays have dual ratings for ac and dc, its normal for the dc
voltage rating to be half the ac voltage rating.

> >Running your relay on 220v 60Hz it will work fine.
>
> Knowing nothing about the contactor, other than that it's specified to
> energize when 240V 50Hz is placed across the coil, your imprimatur is
> premature.

I really dont agree. I do know the basics about relays, and one
normally finds that pull-in occurs at around 50% rated voltage. The OP
is welcome to test theirs to see if it behaves the usual way.

> >Contact closing speed will be slightly slower. Margin will be reduced,
> >but its only being reduced from enormous to slightly less enormous,
> >so its a non-issue except in very unusual situations.
>
> It seems you've forgotten that when the armature makes, and the
> magnetic circuit is closed, the inductance of the coil will rise.

I dont know why you think I've forgotten it. What's relevant here is
inductance in the closed position.

> Such being the case, the current in it will diminish,

true with all relays under all ac conditions. Theyre designed to work
that way.

> reducing the
> hold on the armature and making the contacts more likely to chatter.

No, its exactly how theyre designed to operate.

> >The vibration tolerance of
> >the contacts will be little affected in practice; if your environment
> >is harsh enough to shake the relay contact open, then you've got
> >bigger worries than contacts crackling.
> >If instead you meant you would use it on 110v 60Hz, then dont. But you
> >could use diodes to get a higher dc voltage and use that.
>
> Interesting conjecture.

Where's the conjecture? I get the feeling you could do with bringing
your skills up to speed on relays.

> Something like this?
>
> +-----+
> 120AC>--|~ +|----+
> | | |
> | | [COIL]
> | | |
> 120AC>--|~ -|----+
> +-----+

That would work.

> Since the coil has an impedance of about 6600 ohms at 50Hz, then the
> current through it will be:
>
> E 240V
> I = --- = ------- = 0.036A = 36mA
> Z 6600R
>
> Then, since the coil has a resistance of 4800 ohms, the DC voltage
> across it required to force 36mA through it would be:
>
> E = IR = 0.036A * 4800R ~ 174V.

You're not saying where you got those figures from. Typically dc
rating is half ac rating.

> The peak voltage out of the bridge would be:
>
> E = RMS * sqrt(2) = 120 * 1.414 ~ 170V.
>
> Pretty close, but at 120Hz, the reactance of the coil would increase,
> limiting the current to something less than the 36mA needed to close
> the armature.

The effect of the relay's inductance, when run off a BR, is simply to
smooth the current flow somewhat. Mean current remains much the same.
So we're looking for 120v rms, which is what the BR would deliver.

> However, the reactance of the coil will smooth the current and the
> addition of a capacitor in parallel with the coil will remove some of
> the ripple and allow the coil to see more nearly pure DC.

and overheat the relay by increasing its rms dc voltage to above 120v.

> Here's a simulation showing both ways:
>
> Version 4
> SHEET 1 880 680
> WIRE -144 16 -304 16
> WIRE 112 16 -144 16
> WIRE 448 16 288 16
> WIRE 704 16 448 16
> WIRE -304 80 -304 16
> WIRE 288 80 288 16
> WIRE 448 80 448 64
> WIRE 480 80 448 80
> WIRE 592 80 560 80
> WIRE 704 80 704 64
> WIRE 704 80 672 80
> WIRE -144 112 -144 80
> WIRE -112 112 -144 112
> WIRE 0 112 -32 112
> WIRE 112 112 112 80
> WIRE 112 112 80 112
> WIRE -144 160 -144 112
> WIRE 112 160 112 112
> WIRE 448 160 448 80
> WIRE 544 160 448 160
> WIRE 704 160 704 80
> WIRE 704 160 608 160
> WIRE -304 224 -304 160
> WIRE -144 224 -304 224
> WIRE 112 224 -144 224
> WIRE 288 224 288 160
> WIRE 448 224 288 224
> WIRE 704 224 448 224
> WIRE -304 272 -304 224
> WIRE 288 272 288 224
> FLAG -304 272 0
> FLAG 288 272 0
> SYMBOL ind -128 128 R270
> WINDOW 0 32 56 VTop 0
> WINDOW 3 5 56 VBottom 0
> SYMATTR InstName L1
> SYMATTR Value 15
> SYMBOL voltage -304 64 R0
> WINDOW 3 24 104 Invisible 0
> WINDOW 123 0 0 Left 0
> WINDOW 39 0 0 Left 0
> SYMATTR InstName V1
> SYMATTR Value SINE(0 170 60)
> SYMBOL diode -160 16 R0
> WINDOW 0 4 -52 Left 0
> WINDOW 3 -28 -24 Left 0
> SYMATTR InstName D1
> SYMATTR Value MUR460
> SYMBOL diode 128 80 R180
> WINDOW 0 1 119 Left 0
> WINDOW 3 -33 84 Left 0
> SYMATTR InstName D2
> SYMATTR Value MUR460
> SYMBOL diode 96 160 R0
> WINDOW 0 3 89 Left 0
> WINDOW 3 -27 118 Left 0
> SYMATTR InstName D3
> SYMATTR Value MUR460
> SYMBOL diode -128 224 R180
> WINDOW 0 2 -28 Left 0
> WINDOW 3 -31 -57 Left 0
> SYMATTR InstName D4
> SYMATTR Value MUR460
> SYMBOL res -16 128 R270
> WINDOW 0 32 56 VTop 0
> WINDOW 3 0 56 VBottom 0
> SYMATTR InstName R1
> SYMATTR Value 4800
> SYMBOL ind 464 96 R270
> WINDOW 0 32 56 VTop 0
> WINDOW 3 5 56 VBottom 0
> SYMATTR InstName L2
> SYMATTR Value 15
> SYMBOL voltage 288 64 R0
> WINDOW 3 24 104 Invisible 0
> WINDOW 123 0 0 Left 0
> WINDOW 39 0 0 Left 0
> SYMATTR InstName V2
> SYMATTR Value SINE(0 170 60)
> SYMBOL diode 432 16 R0
> WINDOW 0 4 -52 Left 0
> WINDOW 3 -28 -24 Left 0
> SYMATTR InstName D5
> SYMATTR Value MUR460
> SYMBOL diode 720 80 R180
> WINDOW 0 1 119 Left 0
> WINDOW 3 -33 84 Left 0
> SYMATTR InstName D6
> SYMATTR Value MUR460
> SYMBOL diode 688 160 R0
> WINDOW 0 3 89 Left 0
> WINDOW 3 -27 118 Left 0
> SYMATTR InstName D7
> SYMATTR Value MUR460
> SYMBOL diode 464 224 R180
> WINDOW 0 2 -28 Left 0
> WINDOW 3 -31 -57 Left 0
> SYMATTR InstName D8
> SYMATTR Value MUR460
> SYMBOL res 576 96 R270
> WINDOW 0 32 56 VTop 0
> WINDOW 3 0 56 VBottom 0
> SYMATTR InstName R2
> SYMATTR Value 4800
> SYMBOL cap 608 144 R90
> WINDOW 0 0 32 VBottom 0
> WINDOW 3 32 32 VTop 0
> SYMATTR InstName C1
> SYMATTR Value 10µ
> TEXT -298 246 Left 0 !.tran .05
>
> If the relay is spec'ed as "must make" at 80% of rated current through
> the coil (~29mA), then note that with a 10µF cap in parallel with the
> coil the relay will _always_ make using full-wave rectified 120V 60Hz
> mains.

== 4 of 10 ==
Date: Tues, Aug 30 2011 8:35 am
From: "petrus bitbyter"

"NT" <meow2222@care2.com> schreef in bericht
news:9eae9570-949f-4798-84c2-74062c8df2b1@j1g2000yqn.googlegroups.com...
On Aug 29, 7:03 pm, John Fields <jfie...@austininstruments.com> wrote:
> On Mon, 29 Aug 2011 07:28:53 -0700 (PDT), NT <meow2...@care2.com>
> wrote:
>
>
>
> >On Aug 29, 3:03 pm, John Fields <jfie...@austininstruments.com> wrote:
> >> On Sun, 28 Aug 2011 23:21:56 -0700, DaveC <inva...@invalid.net> wrote:
> >> >I may be able to obtain a very small 2-pole 240 vac contactor I need
> >> >rated
> >> >for 50 Hz only.
>
> >> >If I install it in N. America, what's the implication? Is the hold-in
> >> >magnetism less than if it were 60 Hz? Just noisy?
>
> >> >Please don't ask or suggest other sources. This is a very specific
> >> >device and
> >> >I've not been able to locate other than this.
>
> >> Not knowing the specifics about the coil makes predicting what will
> >> happen at 60Hz difficult.
>
> >> However, assuming that the inductive reactance and resistance of the
> >> coil will remain constant at 50 and 60Hz means that the impedance of
> >> the coil at 60Hz will be 1.2 times (60Hz/50Hz) what it is at 50Hz.
>
> >no, only the L component of the impedance will be 1.2 times as high.
>
> ---
> Well, that's true, so let's just see how far off I was, by using a
> real-world example.
>
> I have an old P&B MR5A here with a 240V 50/60Hz coil.
>
> The coil has a resistance of 4800 ohms, and an open inductance of 14.5
> henrys, so it has an impedance of 6616 ohms at 50 Hz, and 7270 ohms at
> 60 Hz.
>
> 7270 - 6616 = 1.1, so my error was 1 part in 11, or a little less than
> 10%
>
> I can live with that.
> ---
>
>
>
> >> Consequently, the current in the coil at 60Hz will be about 83% of
> >> what it is at 50Hz.
>
> >> If that turns out to be a problem, a higher drive voltage could be
> >> used in order to increase the current, namely 1.2 times 240V; 288V.
>
> >> That could easily be accomplished using a transformer to boost the
> >> 240V mains to 288V, like this: (View with a fixed pitch font.)
>
> >> 240AC>-----+--+
> >> | |
> >> oP||S
> >> R||E
> >> I||Co
> >> | |
> >> | +-----> \
> >> | > 288AC TO COIL
> >> 240AC>-----+--------> /
>
> >> The transformer would need a 240V primary, a 48V secondary, and a VA
> >> rating greater than or equal to the contactor coil's rating.
>
> >these are the kind of 'solutions' that happen when people dont put the
> >relevant numbers to things.
>

> Well, your tone is certainly insulting, while the solution remains
> valid, but since the voltage into the coil will only be 11% low, the
> transformer secondary will only have to supply 26V instead of 48.
>
> In reality, 24V will be fine.
|
| The relay has a voltage margin of around 50%, the mains supply wont
| vary more than 10%, so the transformer is of no use.
|
|
|NT
|

"The relay has a voltage margin of around 50%" How do you know? FAIK the op
did not supply this numbers.

petrus bitbyter

== 5 of 10 ==
Date: Tues, Aug 30 2011 8:38 am
From: David Lesher

DaveC <invalid@invalid.net> writes:

>> It will be happy. If it were a 60Hz on 50, it would not be as happy.
>[David Lesher]

>Interesting. Good to know. It's stuff like this I learn here that I wouldn't
>otherwise know.

Well anytime you run transformers {Be they two fixed windings,
or one fixed and one rotating aka motor, or one fixed &
one sliding aka solenoid or relay....} on LESS than design
frequency, worry. Lower frequencies need more iron.

I'm not sure the slightly less pull-in power will be relevent but
it's possible.

If you do pursue the "make DC and use that..." approach; don't forget
you need to limit the holdin current. One technique is a cap in parallel
with a resistor.

--
A host is a host from coast to coast.................wb8foz@nrk.com
& no one will talk to a host that's close........[v].(301) 56-LINUX
Unless the host (that isn't close).........................pob 1433
is busy, hung or dead....................................20915-1433

== 6 of 10 ==
Date: Tues, Aug 30 2011 8:55 am
From: Jeffrey Angus

On 8/30/2011 10:38 AM, David Lesher wrote:
> Well anytime you run transformers {Be they two fixed windings,
> or one fixed and one rotating aka motor, or one fixed&
> one sliding aka solenoid or relay....} on LESS than design
> frequency, worry. Lower frequencies need more iron.

Hasn't anybody read the original question?

He wants to know if a 50 Hz relay coil will work at 60 Hz.

Jeff

--
"Everything from Crackers to Coffins"

== 7 of 10 ==
Date: Tues, Aug 30 2011 9:44 am
From: Rich Grise

Jeffrey Angus wrote:

> On 8/30/2011 10:38 AM, David Lesher wrote:
>> Well anytime you run transformers {Be they two fixed windings,
>> or one fixed and one rotating aka motor, or one fixed&
>> one sliding aka solenoid or relay....} on LESS than design
>> frequency, worry. Lower frequencies need more iron.
>
> Hasn't anybody read the original question?
>
Yeah. It was answered some days ago.

Guess you gotta be quick. ;-)

Cheers!
Rich

== 8 of 10 ==
Date: Tues, Aug 30 2011 9:49 am
From: Rich Grise

John Fields wrote:
> On Tue, 30 Aug 2011 02:58:19 +0000 (UTC), David Lesher
>>John Fields <jfields@austininstruments.com> writes:
>>
>>>I have an old P&B MR5A here with a 240V 50/60Hz coil.
>>
>>>The coil has a resistance of 4800 ohms, and an open inductance of 14.5
>>>henrys, so it has an impedance of 6616 ohms at 50 Hz, and 7270 ohms at
>>>60 Hz.
>>
>>What's the inductance while closed?
>
> 16 henries, but that measurement was made by closing the armature
> manually.
>
> If there's any real interest I can measure it energized.
>
Well, I guess that depends on what you mean by "real interest" - I'd be
interested in seeing your experimental results, but that's just because
I like seeing experimental results. ;-)

Cheers!
Rich

== 9 of 10 ==
Date: Tues, Aug 30 2011 10:59 am
From: Jeff Liebermann

On Tue, 30 Aug 2011 10:55:10 -0500, Jeffrey Angus <grendelair@aim.com>
wrote:

>Hasn't anybody read the original question?

Nope. With 5 groups in the distribution, I just assumed the original
question to not be worth reading. Besides, some of the groups appear
to be write-only, where nobody (including me) reads the original
question.

>He wants to know if a 50 Hz relay coil will work at 60 Hz.

Well, if it's too much of a risk trying it and checking if it will
explode, there are plenty of 50 to/from 60 Hz converters available for
a small fortune:
<http://www.50hz.com/Rotary/rotary.htm>
If sufficiently low power, one could probably just build a converter
from two motors and a suitable gearbox.

Jeff (part of the problem) L.

--
Jeff Liebermann jeffl@cruzio.com
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

== 10 of 10 ==
Date: Tues, Aug 30 2011 1:37 pm
From: David Lesher

Jeffrey Angus <grendelair@aim.com> writes:

>On 8/30/2011 10:38 AM, David Lesher wrote:
>> Well anytime you run transformers {Be they two fixed windings,
>> or one fixed and one rotating aka motor, or one fixed&
>> one sliding aka solenoid or relay....} on LESS than design
>> frequency, worry. Lower frequencies need more iron.

>Hasn't anybody read the original question?

I have.

>He wants to know if a 50 Hz relay coil will work at 60 Hz.

And that's my point; if it were the other way, he SHOULD worry.
--
A host is a host from coast to coast.................wb8foz@nrk.com
& no one will talk to a host that's close........[v].(301) 56-LINUX
Unless the host (that isn't close).........................pob 1433
is busy, hung or dead....................................20915-1433

==============================================================================
TOPIC: Tek 465
http://groups.google.com/group/sci.electronics.repair/t/b9f473fde6856891?hl=en
==============================================================================

== 1 of 2 ==
Date: Tues, Aug 30 2011 3:14 am
From: "Mark Zacharias"

> http://www.sphere.bc.ca/test/tek1.html
>
> --
> Cheers,
> WB
> .............
>
>
> "Mark Zacharias" <mark_zacharias@labolgcbs.net> wrote in message
> news:4e58de02$0$2960$a8266bb1@newsreader.readnews.com...
>> Just bought a Tek 2246 on the 'Bay. This means the 465 will probably need
>> to be sold, assuming the new one is OK and all.
>>
>> I would entertain serious offers from the good folks who know me here on
>> the Group (USA only, please) prior to putting it up on eBay.
>>
>> Probably about 175.00 plus freight.
>>
>> Yes, this is the same 'scope Mr. Yanik helped me with recently. Replaced
>> a bad bridge rectifier.
>>
>> Everything works great, bright sharp trace, no burns. Physical condition
>> very good, nothing bent or broken, minor scuffs around the case but not
>> involving the face. I have several versions of the manuals etc on PDF.
>>
>> Any questions please ask.
>>
>> Thanks.
>>
>>
>> Mark Z.
>>
>> --
>> "I can't die until the government finds a safe place to bury my liver."
>

"Wild_Bill" <wb_wildbill@XSPAMyahoo.com> wrote in message
news:Xf_6q.144751$BZ.132582@en-nntp-03.dc1.easynews.com...
> Dunno if the need will arise, but Sphere in Canada has a lot of online
> info wrt Tek equipment (and numerous other brands) parts, parts
> cross-reference lists, etc.
>

Yeah - this is where I got that sweep logic IC the last time my 465 broke.
About 60.00 plus frt. Grrr.

Mark Z.

== 2 of 2 ==
Date: Tues, Aug 30 2011 8:01 am
From: Jim Yanik

"Mark Zacharias" <mark_zacharias@labolgcbs.net> wrote in
news:4e5cb7ec$0$2871$a8266bb1@newsreader.readnews.com:

>> http://www.sphere.bc.ca/test/tek1.html
>>
>> --
>> Cheers,
>> WB
>> .............
>>
>>
>> "Mark Zacharias" <mark_zacharias@labolgcbs.net> wrote in message
>> news:4e58de02$0$2960$a8266bb1@newsreader.readnews.com...
>>> Just bought a Tek 2246 on the 'Bay. This means the 465 will probably
>>> need to be sold, assuming the new one is OK and all.
>>>
>>> I would entertain serious offers from the good folks who know me
>>> here on the Group (USA only, please) prior to putting it up on eBay.
>>>
>>> Probably about 175.00 plus freight.
>>>
>>> Yes, this is the same 'scope Mr. Yanik helped me with recently.
>>> Replaced a bad bridge rectifier.
>>>
>>> Everything works great, bright sharp trace, no burns. Physical
>>> condition very good, nothing bent or broken, minor scuffs around the
>>> case but not involving the face. I have several versions of the
>>> manuals etc on PDF.
>>>
>>> Any questions please ask.
>>>
>>> Thanks.
>>>
>>>
>>> Mark Z.
>>>
>>> --
>>> "I can't die until the government finds a safe place to bury my
>>> liver."
>>
>
> "Wild_Bill" <wb_wildbill@XSPAMyahoo.com> wrote in message
> news:Xf_6q.144751$BZ.132582@en-nntp-03.dc1.easynews.com...
>> Dunno if the need will arise, but Sphere in Canada has a lot of
>> online info wrt Tek equipment (and numerous other brands) parts,
>> parts cross-reference lists, etc.
>>
>
> Yeah - this is where I got that sweep logic IC the last time my 465
> broke. About 60.00 plus frt. Grrr.
>
> Mark Z.
>
>

IIRC,that is cheaper than TEK sold it(new stock).
155-0049-02,right?

What I wonder is where all the stock TEK had on hand went to when they made
the 400 series obsolete? TEK's Recycling store?

I know some small part of it went to an employee instead of the trash where
it was supposed to go. TEK throws out a lot of old parts(instead of
"close-out" batch-selling them to 3rd parties),and takes a tax writeoff on
them.
But I knew one guy who instead had it all boxed up and took it home,after
one Service Center bench stock purge.
If I had tried that,I'd have been fired.

--
Jim Yanik
jyanik
at
localnet
dot com

==============================================================================
TOPIC: Michael Patrick Jost (photography)
http://groups.google.com/group/sci.electronics.repair/t/403b7df8a90b31cd?hl=en
==============================================================================

== 1 of 1 ==
Date: Tues, Aug 30 2011 4:39 am
From: Kulin Remailer

Michael Patrick Jost photograph of the London Monument:

http://groups.google.com/group/soc.culture.british/browse_thread/thread/3904dadad6b2e524?pli=1

http://michaelpatrickjost.wordpress.com

==============================================================================
TOPIC: Tek 7000 Series Fixtures 067-0655-00 vs 067-0589-00 fixtures
http://groups.google.com/group/sci.electronics.repair/t/2ab39c9efbfedb88?hl=en
==============================================================================

== 1 of 1 ==
Date: Tues, Aug 30 2011 5:56 am
From: sck0006

We're running through the calibration on our 067-0587-10 Standardizers
and they're failing frequency response. All points lead to the
067-0655-00 fixture going bad, which we only have one of. We tried to
substitute the 067-0589-00 fixture in place of it and pull the + & -
signals off of it, but the frequency response was even worse, on the
order of -12% at points. What is the main difference between the
067-0655-00 and the 067-0589-00? The 0655 looks like they've spent
significant effort shielding the pickoff points, and the 0589 has a
little more unshielded coax showing. However, the flexible extender
board has a similar amount of unshielded coax to the 0589 and seems to
pass the signals just fine. Is it just the rolloff of the coax used
in the 0589?

Are there any engineers out there that worked on the 7000's still
around?

Thanks for any help,

Steve

==============================================================================
TOPIC: 2011 HOT PICS
http://groups.google.com/group/sci.electronics.repair/t/3729e3e35291d594?hl=en
==============================================================================

== 1 of 1 ==
Date: Tues, Aug 30 2011 10:10 am
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==============================================================================
TOPIC: Why do some manufacturers wrap the electrolytic capacitor that gets the
hottest in a switching power supply in shrink wrap?
http://groups.google.com/group/sci.electronics.repair/t/2a675f3c64fd62cc?hl=en
==============================================================================

== 1 of 3 ==
Date: Tues, Aug 30 2011 1:47 pm
From: Chuck

Extron has been doing this for years and of course it is the first
part to fail in their units. Smart Technologies Sympodium power
supplies, that they have contract built in China, fail in a year or so
for the same reason. Technicians and electronic engineers at my work
place can't think of a rational reason why these manufacturers do
this. This is pro gear where reliability is a great concern so it
doesn't seem to be planned failure mode. Thanks. Chuck

== 2 of 3 ==
Date: Tues, Aug 30 2011 2:48 pm
From: Jim Yanik

Chuck <chuckh@deja.net> wrote in
news:3giq5793mdtgi0f6ssmf2pp79bn9ukbeuv@4ax.com:

> Extron has been doing this for years and of course it is the first
> part to fail in their units. Smart Technologies Sympodium power
> supplies, that they have contract built in China, fail in a year or so
> for the same reason. Technicians and electronic engineers at my work
> place can't think of a rational reason why these manufacturers do
> this. This is pro gear where reliability is a great concern so it
> doesn't seem to be planned failure mode. Thanks. Chuck
>

IMO,in a proper design,the caps should not be getting hot.
Caps should be sized and rated properly,with a fair amount of excess
capacity,not sized/rated right at the margins.
We have inexpensive thermal imaging available that can identify hot spots
so that they can be corrected before the design is finalized.

--
Jim Yanik
jyanik
at
localnet
dot com

== 3 of 3 ==
Date: Tues, Aug 30 2011 3:07 pm
From: "Michael A. Terrell"

Chuck wrote:
>
> Extron has been doing this for years and of course it is the first
> part to fail in their units. Smart Technologies Sympodium power
> supplies, that they have contract built in China, fail in a year or so
> for the same reason. Technicians and electronic engineers at my work
> place can't think of a rational reason why these manufacturers do
> this. This is pro gear where reliability is a great concern so it
> doesn't seem to be planned failure mode. Thanks. Chuck

Then you need all new technicians and engineers. They have to
minimize lead inductance of the capacitors, at high frequncies. Unless
you don't really want to remove the ripple.

--
You can't have a sense of humor, if you have no sense.

==============================================================================
TOPIC: Tektronix 7603
http://groups.google.com/group/sci.electronics.repair/t/efb86f5dc14fc24b?hl=en
==============================================================================

== 1 of 2 ==
Date: Tues, Aug 30 2011 3:05 pm
From: Jeff Urban

I do not care to join any more groups. This is sci.electronics.repair
correct ? This is an electronic instrument I wish to repair.

I need another internet ID like a hole in the head, and let me tell
you when I was in my twenties I got shot in the face, so I can assure
you I don't need any more holes in my head. What is Usenet dead ? I
know I am posting through Google but that's the only way I have right
now. I was here a long time ago and if I could I would retrieve my old
ID, but I can't.

S.E.R. is dead ? I have to go to yahoo ?

Sorry, I'll just sell the Tek. Fuck it.

== 2 of 2 ==
Date: Tues, Aug 30 2011 3:12 pm
From: "Michael A. Terrell"

Jeff Urban wrote:
>
> I do not care to join any more groups. This is sci.electronics.repair
> correct ? This is an electronic instrument I wish to repair.
>
> I need another internet ID like a hole in the head, and let me tell
> you when I was in my twenties I got shot in the face, so I can assure
> you I don't need any more holes in my head. What is Usenet dead ? I
> know I am posting through Google but that's the only way I have right
> now. I was here a long time ago and if I could I would retrieve my old
> ID, but I can't.
>
> S.E.R. is dead ? I have to go to yahoo ?
>
> Sorry, I'll just sell the Tek. Fuck it.

This is the reason so many have left the group for greener pastures.
They got tired of whiny jerks like you.

All you need is a Yahoo Email address to join any Yahoo group that
will take you, but they aren't interested in pissing and moaning.

You aren't related to Bill Turner, by any chance? You bitch and
whine just like he used to.

--
You can't have a sense of humor, if you have no sense.

==============================================================================

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