Mains plugs for 12V DC

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Check out this months SC.
Someone has mailed in showing off a 12V power plug system for their
bench - using mains power plugs on all the 12V gear. And he hopes the
idea catches on!

I don't know what's sillier, the idea itself, or SC for actually
publishing it (even with the hammering and warning).

Dave.

Re: Mains plugs for 12V DC

"David L. Jones"
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** I believe it is totally illegal to use a 240 volt plug or socket for any
other purpose than as a mains connector.

Back when I was a keen model power boat racer, one of the club members
showed up at the lakeside with a new 12V starter motor fitted with a
standard 3 pin mains plug.  He had also fitted a double power point to his
tool box to allow connection to the 12 volt battery he kept inside. The
other socket allowed him to plug in a 12V fuel pump.

Thing is, the guy made his living as an electrician  !!!

Besides being ludicrously  DANGEROUS  the idea will not work reliably as the
brass plug pins and female socket parts are very prone to tarnishing and
when thick enough this tarnish will fully insulate at 12 volts.

One of the reasons why the earth pin has to be nickel plated nowadays.



.....   Phil





Re: Mains plugs for 12V DC
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When all you have is a hammer, everything looks like a nail I guess!

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Yup. Silly, dangerous, and a poor choice.

So what would other people use as a bench 12V connector for gear?
First thing that springs to mind for me would be XLR connectors. Easy
to mount a strip of those on a panel, and 16A types are readily
available. Get a 4 way type and double up on the pins.

Dave.

Re: Mains plugs for 12V DC

"David L. Jones"
"Phil Allison"
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** I have used 4 pin " CB mic " connectors ( DSE cat  P1834)  for a bench
PSU that outputs +/-15 volts regulated DC to connect up various audio test
items I made to run from that voltage.

Good for a couple of amps.

Nice and cheap at $ 2.49 each  -  even less at WES.



....   Phil





Re: Mains plugs for 12V DC
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Have also used 4-pin 'CB mic' plugs for exactly the same purpose and can
recommend them. Other than that there are also DC barrel connectors which are
designed for low power DC use.


Re: Mains plugs for 12V DC

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Aren't there mains style clipsal/hpm or whatever plugs/sockets with two pins
arranged in a "T" configuration that are intended for DC applications? Maybe
my memory is faulty.



Re: Mains plugs for 12V DC

"Den"
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**This what you mean ?

http://updates.clipsal.com/ClipsalOnline/ProductInformation.aspx?searchMode=contents&first30%&skip23%&contentId56%1


**  32 volt,  15 amp AC only it says.

Same issues with tarnishing if used at a lower voltage plus a  NASTY  arcing
issue if used for high current DC.



.....   Phil



Re: Mains plugs for 12V DC

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http://updates.clipsal.com/ClipsalOnline/ProductInformation.aspx?searchMode=contents&first30%&skip23%&contentId56%1
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Yep those are them - also at http://tinyurl.com/4qhugc I think they were
used by Telecom in the 70s & 80s in vehicles, trucks, 4wds etc for running
accessories in the field.



Re: Mains plugs for 12V DC


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http://updates.clipsal.com/ClipsalOnline/ProductInformation.aspx?searchMode=contents&first30%&skip23%&contentId56%1
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I agree. However, this page promotes them as "Suitable for most DC
applicacations" (their
typo - not mine) and "ultra reliable". I don't think so..........

http://www.lakecomm.com.au/connectors-cable.html

Andy

Re: Mains plugs for 12V DC
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    I used to use those back in the 1970s. I think they're called 'ELV'
(Extra Low Voltage) connectors and are for 32V maximum if I remember
correctly.
    Dunno if they're still around ... too busy to go searching.



Re: Mains plugs for 12V DC

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as
and


And yet strangely all the slot car tracks 30 years ago used 240V sockets for
the 12V hand controllers.
I have no idea if the remaining ones still do.



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Most people use the car cigarette lighter plug/sockets, or the smaller
"merit" versions. Neither is ideal, but at least most people will instantly
recognise what to expect.


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pins
Maybe


Nope, your memory is fine, that's what my enlarger (12v halogen) uses. They
were rated to 32V from memory.

MrT.



Re: Mains plugs for 12V DC

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   I used the 2 pin .093" MOLEX connectors on my benches about 25 years
ago.  They were rated to 10 amps per pin, and held up well for the 10
tears I used them.  A simple rectangular notch in a piece of angle
aluminum made a nice mounting bracket.  Best o all, they were cheap, and
always in stock, since I used them on some job sites.


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Re: Mains plugs for 12V DC
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A local radio ham with who I have "foxhunted" uses RCS plugs.
They're not terribly strong, but there's heaps of contact
area and they won't come unplugged by themselves. Audio gear
always has DC isolation to 12V at least, so though inadvertent
mis-connection might make some nasty noises, no smoke.

Clifford Heath.

Re: Mains plugs for 12V DC
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Ugh, that should have been "RCA" plugs, sorry.

Re: Mains plugs for 12V DC

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I found those only useful for a short life. Minly they lost contact on the
inner pin. OTOH, I only used "cheapo" standard and not an expensive brand
name version.


Re: Mains plugs for 12V DC
On Thu, 25 Sep 2008 20:22:05 -0700 (PDT), "David L. Jones"

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An old friend did something like that for his radio gear, only he used
DC sockets to supply 240VAC. <shrug>

He blew up at least one radio that I know of.

- Franc Zabkar
--
Please remove one 'i' from my address when replying by email.

Re: Mains plugs for 12V DC

"Franc Zabkar" <
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**  I'm sure I remember a story in EA magazine,  maybe in the servicemen
column, about a man who used 3 pin mains plugs to connect a big woofer
cabinet to an amplifier.

One day, his wife unplugged the woofer to do the vacuuming and then ....

BIG  bang   -  no more woof.



.....   Phil






Re: Mains plugs for 12V DC
On Thu, 25 Sep 2008 20:22:05 -0700 (PDT), "David L. Jones"

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I remember an Iranian friend telling me that for a while Iran used the
same wall sockets for AC mains as for telephones. People would
sometimes plug a telephone into the mains. The phone would ring,
presumably at the mains frequency, and then die.

This Wikipedia article shows one plug style as CEE 7/17 Euro 2 pin:
http://en.wikipedia.org/wiki/List_of_countries_with_mains_power_plugs,_voltages_and_frequencies

This article shows that the CEE 7/16 2-pin plug was used in older
installations:
http://en.wikipedia.org/wiki/Telephone_plug

- Franc Zabkar
--
Please remove one 'i' from my address when replying by email.

Re: Mains plugs for 12V DC

"Franc Zabkar"

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**  The common 4mm " double banana" plug and the mating dual 4mm binding
post terminals in 19 mm spacing are   BANNED  in the EU  for use on any sort
of audio or entertainment equipment.

http://www.pomonaelectronics.com/index.php?pageNum_rsProduct=2&totalRows_rsProduct89%&i=prodsub&parent=HWARE&catBA%NANAPLGJCK&getDetails =


Why ????

Cos it plugs straight into this:

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

Ouch  !!!



....   Phil





Re: Mains plugs for 12V DC
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Yes, got quite a shock seeing that,  however in times gone by I have
seen mains fittings used for car to trailer connectors, as connectors
for "slot car" hand controllers (for public use) in an amusement
centre, and even as speaker connectors when I was in school (cant
remember if it was the 240 type or the 2 pin US type). Fortunately now
there are many more "correct" low voltage plugs and sockets available
to the hobbyist via Auto suppliers, dick smith and similar stores,
this probably wasn't the case prior to the 1970s, and people would use
what was commonly available - household fittings.

I can only assume that SC did this in order to provide an example of
HOW NOT to do something.

If he ABSOLUTELY HAD TO use this system, he should have at least used
the neutral and earth as the + and - connectors, and sawn off the
active pin.  At least then, there would be much less risk of danger if
it was plugged into a 240v socket mistakenly.

The other problem with his system is that Mains fittings are clearly
labelled "AC ONLY" and are probably not designed to be used with 10A
DC, especially if there are switches involved.  You are also limited
to 10amps (via the CB in the power board he used) which kind of
defeats the purpose a bit if you want to connect higher current
equipment.

SC should have pointed out that for low voltage use, (32v lighting
plants?) there is a plug and socket available - similar to the 240v
unit, but with the pins arranged in a " T " configuration.  Dick smith
had these, and no doubt Haymans etc would be able to get them for
you.

Alternately, go to Super Cheap or Autobarn, and check out the
connectors etc that they use for the high wattage sound system
installs. These would be far superior in current handling to any mains
plugs.


Also this Reminded me of another article in either EA or ETI some 25
years back showing where some fool had decided to convert his Telecom
phone system to a mains plug and socket arrangement so he could carry
the phone around his house and plug it in anywhere he wanted.  (at
that time it probably was near impossible to buy the proper "Telecom"
type sockets for the average hobbyist?)




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