Mechanical Relays

[Bill Sloman]

On Wednesday, October 30, 2019 at 9:11:37 PM UTC+11, Chris Jones wrote:

On 29/10/2019 19:39, Cursitor Doom wrote:
Gentlemen,

I have acquired, over the years, a great many mechanical relays (I think
it's the same word in both US and British English). They are bulky, heavy
and I don't find myself using them much any more, preferring to do
switching via MOSFETs instead. The question is: is there any point in
keeping the old relays in this day and age? If everything they can do can
be done by MOSFETs then there seems very little point. Any suggestions?
A relay is more likely to survive static discharges, nearby lightning etc.

I was thinking I might as well unwind their cores onto spools (I have an
engine lathe) keep the wire thusly obtained and throw the rest away?
Sometimes I do use relays as a source of winding wire - it is hard to
buy small quantities of very fine gauges any other way.

https://www.scientificwire.com/

worked for me. 500 grams of wire isn't a great deal.

<snipped good advice>

--
Bill Sloman, Sydney

 

[Chris Jones]

On 30/10/2019 23:21, Bill Sloman wrote:

On Wednesday, October 30, 2019 at 9:11:37 PM UTC+11, Chris Jones wrote:
On 29/10/2019 19:39, Cursitor Doom wrote:
Gentlemen,

I have acquired, over the years, a great many mechanical relays (I think
it's the same word in both US and British English). They are bulky, heavy
and I don't find myself using them much any more, preferring to do
switching via MOSFETs instead. The question is: is there any point in
keeping the old relays in this day and age? If everything they can do can
be done by MOSFETs then there seems very little point. Any suggestions?
A relay is more likely to survive static discharges, nearby lightning etc.

I was thinking I might as well unwind their cores onto spools (I have an
engine lathe) keep the wire thusly obtained and throw the rest away?
Sometimes I do use relays as a source of winding wire - it is hard to
buy small quantities of very fine gauges any other way.

https://www.scientificwire.com/

worked for me. 500 grams of wire isn't a great deal.

I do buy some wires from them, but for e.g. 25um wire, their minimum
purchase is 300g and it costs ÂŁ40 plus international delivery.

As an example, the wire in a 12V, 24V or 48V relay can be surprisingly
fine, and one tiny relay provides a more than sufficient quantity for my
patience, usually for no cost due to my excessive hoard of e-waste. I
have the spool from one of these relays stuck on a makeshift spindle
running in crude pivots, mounted inside a tin can with a lid to keep
dust out, so that when I want some, e.g. for fixing fine PCB traces, I
just open the tin and unwind a bit.

 

[Jeff Layman]

On 30/10/19 09:55, Phil Allison wrote:

Michael Kellett wrote:

------------------------


** I remember seeing OC44s back in the 60s, cos it was safe for kids
to play with battery powered stuff.

If you scraped the black paint off one, they made dandy photo-transistors.



At first, some of the later ones had opaque gunge inside - I can
remember my Dad explaining this to me.
The gunge may not have been malicious - maybe bright light could get
through defects in the black paint.


** The "gunge" was silicone grease.

Harmless, thermally conductive and obviated the need for vacuums.

Lotsa Germanium devices had the stuff packed inside.

Some interesting background on the relationship - or rather not -
between the OC71 and OCP71 here (just before halfway down the page):
<http://www.wylie.org.uk/technology/semics/Mullard/Mullard.htm>

--

Jeff

 

On Thu, 31 Oct 2019 00:13:03 +1100, Chris Jones
<lugnut808@spam.yahoo.com> wrote:

On 30/10/2019 23:21, Bill Sloman wrote:
On Wednesday, October 30, 2019 at 9:11:37 PM UTC+11, Chris Jones wrote:
On 29/10/2019 19:39, Cursitor Doom wrote:
Gentlemen,

I have acquired, over the years, a great many mechanical relays (I think
it's the same word in both US and British English). They are bulky, heavy
and I don't find myself using them much any more, preferring to do
switching via MOSFETs instead. The question is: is there any point in
keeping the old relays in this day and age? If everything they can do can
be done by MOSFETs then there seems very little point. Any suggestions?
A relay is more likely to survive static discharges, nearby lightning etc.

I was thinking I might as well unwind their cores onto spools (I have an
engine lathe) keep the wire thusly obtained and throw the rest away?
Sometimes I do use relays as a source of winding wire - it is hard to
buy small quantities of very fine gauges any other way.

https://www.scientificwire.com/

worked for me. 500 grams of wire isn't a great deal.

I do buy some wires from them, but for e.g. 25um wire, their minimum
purchase is 300g and it costs Ł40 plus international delivery.

As an example, the wire in a 12V, 24V or 48V relay can be surprisingly
fine, and one tiny relay provides a more than sufficient quantity for my
patience, usually for no cost due to my excessive hoard of e-waste. I
have the spool from one of these relays stuck on a makeshift spindle
running in crude pivots, mounted inside a tin can with a lid to keep
dust out, so that when I want some, e.g. for fixing fine PCB traces, I
just open the tin and unwind a bit.

Here in the US, it's cheap and easy to get magnet and bus and other
wire from ebay or amazon. More official sources, like MWS and
electronic distributors, tend to be very expensive.

Watch out for jewelry-type plated "copper" bus wire. It's very stiff
and doesn't solder well. Could be hard-drawn, or some cheap alloy.





--

John Larkin Highland Technology, Inc

lunatic fringe electronics

 

On Tue, 29 Oct 2019 04:21:44 -0700 (PDT), Phil Allison
<pallison49@gmail.com> wrote:

Michael Kellett wrote:

----------------------


Imagine if I'd kept all the OC44 and other OCxx transistors I had when I
was 12 - going for Ł10 a pop on Ebay now !



** I remember seeing OC44s back in the 60s, cos it was safe for kids to play with battery powered stuff.

If you scraped the black paint off one, they made dandy photo-transistors.



..... Phil

GE's early plastic transistors, similar to TO-92 package, were made of
a tan expoxy and were photosensitive. That made for some interesting
offset and hum problems. A circuit would work great until the boss
wandered over to check, and he blocked the light.



--

John Larkin Highland Technology, Inc

lunatic fringe electronics

 

On Tue, 29 Oct 2019 22:47:31 -0400, Joseph Gwinn
<joegwinn@comcast.net> wrote:

On Oct 29, 2019, Winfield Hill wrote
(in article <qp905h031kp@drn.newsguy.com&gt:

Cursitor Doom wrote...

Gentlemen,

I have acquired .. a great many mechanical relays ...

Haha, mechanical relays vs MOSFETs, IGBTs. Some PROs:

* much lower capacitance (sub pF)
* handle higher current (contactors)
* lower voltage drop (sub uV, zero)
* handle higher voltages (30kV, yep)
* lower power (latching types)

Here's an example of a 100A 1.2kV switching application
that benefited from a relay taking over most of the time.
From the new x-Chapters book: Fast magnetic-field shutoff.

https://www.dropbox.com/s/5hj9idbou3jct8v/3x.21_fast-mag-field-shutoff.pdf?dl=
1

Win,

Just curious - does AoE cover mercury-pool ignitrons?

.<https://en.wikipedia.org/wiki/Ignitron

Are they still in use? Mercury has a bad reputation lately.

Think of it as a *very* large and rugged thyratron, suitable for an aluminum
pot line, for instance.

I suppose solid-state thyratrons could be used to drive the igniter (gate)
terminal. Maybe.

Joe Gwinn

--

John Larkin Highland Technology, Inc

lunatic fringe electronics

 

[Joseph Gwinn]

On Oct 30, 2019, jlarkin@highlandsniptechnology.com wrote
(in article<049jre9vg8r7b7v5tbigrhho615dtfai97@4ax.com&gt:

On Tue, 29 Oct 2019 22:47:31 -0400, Joseph Gwinn
joegwinn@comcast.net> wrote:

On Oct 29, 2019, Winfield Hill wrote
(in article <qp905h031kp@drn.newsguy.com&gt:

Cursitor Doom wrote...

Gentlemen,

I have acquired .. a great many mechanical relays ...

Haha, mechanical relays vs MOSFETs, IGBTs. Some PROs:

* much lower capacitance (sub pF)
* handle higher current (contactors)
* lower voltage drop (sub uV, zero)
* handle higher voltages (30kV, yep)
* lower power (latching types)

Here's an example of a 100A 1.2kV switching application
that benefited from a relay taking over most of the time.
From the new x-Chapters book: Fast magnetic-field shutoff.

https://www.dropbox.com/s/5hj9idbou3jct8v/3x.21_fast-mag-field-shutoff.pdf

dl=1

Win,

Just curious - does AoE cover mercury-pool ignitrons?

.<https://en.wikipedia.org/wiki/Ignitron

Are they still in use? Mercury has a bad reputation lately.

They are still made and used, but those units are large-scale industrial,
large but few. This is at a level where semiconductors cannot go.

..<https://www.relltubes.com/products/High-Energy-Transfer-
Products/Ignitron.html?Manufacturer=178>

I think
that ignitions are special order these days. I would also guess that there
are Russian suppliers.

In the earlier wiki, follow the link "Comprehensive Study of High Power
Ignitrons
(https://web.archive.org/web/20110815202923/http://etd.lib.ttu.edu/theses/avai
lable/etd-02262009-31295006979529/unrestricted/31295006979529.pdf) Diana Lynn
Loree" for a survey.

By the way, she references AoE.

In the high microwave region, Gyrotrons rule.

Joe Gwinn

..

Think of it as a *very* large and rugged thyratron, suitable for an aluminum
pot line, for instance.

I suppose solid-state thyratrons could be used to drive the igniter (gate)
terminal. Maybe.

Joe Gwinn

 

[Cursitor Doom]

On Wed, 30 Oct 2019 21:11:32 +1100, Chris Jones wrote:

Sometimes I do use relays as a source of winding wire - it is hard to
buy small quantities of very fine gauges any other way. If you do this
then I suggest that you store it in the original relay. This way it is
more compact (much packaging is required to store winding wire without
scratching its insulation), avoids unnecessary damage to the wire due to
re-winding onto a spool, avoids investing your time in the work of
re-winding it that may never pay off if you happen not to require the
wire, and allows you to use the relay as a relay if that turns out to be
more useful to you sooner.

Well, I can't argue with any of that! Thanks.



--
This message may be freely reproduced without limit or charge only via
the Usenet protocol. Reproduction in whole or part through other
protocols, whether for profit or not, is conditional upon a charge of
GBP10.00 per reproduction. Publication in this manner via non-Usenet
protocols constitutes acceptance of this condition.

 

[legg]

On 29 Oct 2019 02:18:41 -0700, Winfield Hill <winfieldhill@yahoo.com>
wrote:

Cursitor Doom wrote...

Gentlemen,

I have acquired .. a great many mechanical relays ...

Haha, mechanical relays vs MOSFETs, IGBTs. Some PROs:

* much lower capacitance (sub pF)
* handle higher current (contactors)
* lower voltage drop (sub uV, zero)
* handle higher voltages (30kV, yep)
* lower power (latching types)

Here's an example of a 100A 1.2kV switching application
that benefited from a relay taking over most of the time.
From the new x-Chapters book: Fast magnetic-field shutoff.

https://www.dropbox.com/s/5hj9idbou3jct8v/3x.21_fast-mag-field-shutoff.pdf?dl=1

The compound combination is used in transfer switches, in order to
avoid/control arcing across the mechanical contacts.

The semiconductor handle the actual transfer, in some cases while the
heavy armatures are still 'in the air'.

RL

 

[Winfield Hill]

legg wrote...

On 29 Oct 2019 02:18:41 -0700, Winfield Hill <winfieldhill@yahoo.com
wrote:

Cursitor Doom wrote...

Gentlemen,

I have acquired .. a great many mechanical relays ...

Haha, mechanical relays vs MOSFETs, IGBTs. Some PROs:

* much lower capacitance (sub pF)
* handle higher current (contactors)
* lower voltage drop (sub uV, zero)
* handle higher voltages (30kV, yep)
* lower power (latching types)

Here's an example of a 100A 1.2kV switching application
that benefited from a relay taking over most of the time.
From the new x-Chapters book: Fast magnetic-field shutoff.

https://www.dropbox.com/s/5hj9idbou3jct8v/3x.21_fast-mag-field-shutoff.pdf?dl=1

The compound combination is used in transfer switches, in
order to avoid/control arcing across the mechanical contacts.

The semiconductor handle the actual transfer, in some cases
while the heavy armatures are still 'in the air'.

Rob, are these hybrid AC-line transfer switches available
as standard commercial modules?


--
Thanks,
- Win

 

[Piotr Wyderski]

Chris Jones wrote:

Sometimes I do use relays as a source of winding wire - it is hard to
buy small quantities of very fine gauges any other way.

http://sklep.remagas.pl/en/materia%C5%82y-do-produkcji

Best regards, Piotr

 

[Piotr Wyderski]

jlarkin@highlandsniptechnology.com wrote:

> Are they still in use? Mercury has a bad reputation lately.

There are two isotopes of mercury in use, actually. The poisonous one
was used in mercury thermometers, which have been recently banned in the
EU for that reason. The other, good for the environment, is still used
in fluorescent light bulbs as a viable replacement of incadescent devices.

Just exercising doublethink...

Best regards, Piotr

 

[Piotr Wyderski]

Cursitor Doom wrote:

I was thinking I might as well unwind their cores onto spools (I have an
engine lathe) keep the wire thusly obtained and throw the rest away?

Magnet wire is cheap and the enamel can develop cracks during rewinding.
I never re-use the wire for that reason. Throw it away.

There are two advantages of mechanical relays: extreme overload handling
capability and the low resistance normally-close path. Hard to emulate
with a MOSFET -- the best depletion mode ones I know are 300mOhm.
It is not unusual to get 10mOhm end-to-end with a relay.

Best regards, Piotr

 

[John Larkin]

On Fri, 1 Nov 2019 20:01:38 +0100, Piotr Wyderski
<peter.pan@neverland.mil> wrote:

Cursitor Doom wrote:

I was thinking I might as well unwind their cores onto spools (I have an
engine lathe) keep the wire thusly obtained and throw the rest away?

Magnet wire is cheap and the enamel can develop cracks during rewinding.
I never re-use the wire for that reason. Throw it away.

There are two advantages of mechanical relays: extreme overload handling
capability and the low resistance normally-close path. Hard to emulate
with a MOSFET -- the best depletion mode ones I know are 300mOhm.
It is not unusual to get 10mOhm end-to-end with a relay.

Best regards, Piotr

And a fraction of a pF off. And GHz bandwidth. And DPDT for cheap.

--

John Larkin Highland Technology, Inc
picosecond timing precision measurement

jlarkin att highlandtechnology dott com
http://www.highlandtechnology.com

 

On Friday, 1 November 2019 19:11:48 UTC, Piotr Wyderski wrote:

jlarkin@highlandsniptechnology.com wrote:

Are they still in use? Mercury has a bad reputation lately.

There are two isotopes of mercury in use, actually. The poisonous one
was used in mercury thermometers, which have been recently banned in the
EU for that reason. The other, good for the environment, is still used
in fluorescent light bulbs as a viable replacement of incadescent devices.

Just exercising doublethink...

Best regards, Piotr

Far more than two isotopes - all of them poisonous! (But you know that
already - as do the dentists who still use amalgam fillings.)

John

 

[Rick C]

On Friday, November 1, 2019 at 6:24:58 PM UTC-4, jrwal...@gmail.com wrote:

On Friday, 1 November 2019 19:11:48 UTC, Piotr Wyderski wrote:
jlarkin@highlandsniptechnology.com wrote:

Are they still in use? Mercury has a bad reputation lately.

There are two isotopes of mercury in use, actually. The poisonous one
was used in mercury thermometers, which have been recently banned in the
EU for that reason. The other, good for the environment, is still used
in fluorescent light bulbs as a viable replacement of incadescent devices.

Just exercising doublethink...

Best regards, Piotr

Far more than two isotopes - all of them poisonous! (But you know that
already - as do the dentists who still use amalgam fillings.)

John

Not sure what word Piotr intended, but I'm pretty sure it wasn't "isotope". Generally there are three forms of mercury, gas, metal and compounds. Compounds can be organic or inorganic. Some are seriously deadly, others are just not very good to have around.

Interesting note, metallic mercury forms amalgams with a number of other elements including aluminum. A small amount of mercury will essentially dissolve a large amount of aluminum so that it is not allowed on aircraft lest a small spill cause structural damage in a not so visible part of the air frame.

--

Rick C.

- Get 1,000 miles of free Supercharging
- Tesla referral code - https://ts.la/richard11209

 

[Piotr Wyderski]

Rick C wrote:

> Not sure what word Piotr intended, but I'm pretty sure it wasn't "isotope".

I was just kidding to indicate that whether mercury is poisonous or
healthy depends on the amount of cubic dollars being at the disposal of
a particular lobby...

A small amount of mercury will essentially dissolve a large amount of
aluminum so that it is not allowed on aircraft lest a small spill
cause structural damage in a not so visible part of the air frame.

This is how Polish slaves were destroying German aluminum aircraft
engines in their factories during WW2. A sure immediate death penalty,
but some of them were still doing that.

Gallium is good, too.

Best regards, Piotr

 

On Saturday, 2 November 2019 00:18:35 UTC, Piotr Wyderski wrote:

Rick C wrote:

Not sure what word Piotr intended, but I'm pretty sure it wasn't "isotope".

I was just kidding to indicate that whether mercury is poisonous or
healthy depends on the amount of cubic dollars being at the disposal of
a particular lobby...

Another example is of course lead. Its not allowed in solder, but
car batteries are permitted to use huge quantities. Similarly, large
amounts of lead can be used in roofing a building, but lead in paint is
forbidden.
John

 

[Rick C]

On Saturday, November 2, 2019 at 3:18:05 AM UTC-4, jrwal...@gmail.com wrote:

On Saturday, 2 November 2019 00:18:35 UTC, Piotr Wyderski wrote:
Rick C wrote:

Not sure what word Piotr intended, but I'm pretty sure it wasn't "isotope".

I was just kidding to indicate that whether mercury is poisonous or
healthy depends on the amount of cubic dollars being at the disposal of
a particular lobby...
Another example is of course lead. Its not allowed in solder, but
car batteries are permitted to use huge quantities. Similarly, large
amounts of lead can be used in roofing a building, but lead in paint is
forbidden.
John

Do you seriously not understand the differences?

--

Rick C.

+ Get 1,000 miles of free Supercharging
+ Tesla referral code - https://ts.la/richard11209

 

[Chris Jones]

On 02/11/2019 06:16, Piotr Wyderski wrote:

Chris Jones wrote:

Sometimes I do use relays as a source of winding wire - it is hard to
buy small quantities of very fine gauges any other way.

http://sklep.remagas.pl/en/materia%C5%82y-do-produkcji

    Best regards, Piotr

Thanks, bookmarked.