Mains plugs for 12V DC

[F Murtz]

kreed wrote:

On Sep 26, 1:22 pm, "David L. Jones" <altz...@gmail.com> wrote:
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.

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?)



We used to use the two parallel pins for 32v or less ac and the

polarised [t shaped] ones for 32v or less dc.

 

[terryc]

On Sat, 27 Sep 2008 11:49:24 +1000, Clifford Heath wrote:

Clifford Heath wrote:
David L. Jones wrote:
So what would other people use as a bench 12V connector for gear?
A local radio ham with who I have "foxhunted" uses RCS plugs.

Ugh, that should have been "RCA" plugs, sorry.

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.

 

[aussiblu]

There are the 12 Volt - 32 Volt DC 2 pin T automotive/caravan
types described here
http://www.caraworld.com.au/12velectrical.html as fixed polarity
plugs and sockets that Malz in WA sell under a KC brand I think.
Also here
http://www.aquavolt.com.au/cgi/index.cgi/shopfront/view_by_category?category_id=1107141381

--
Regards
Blue

Remove ZX from email address to reply directly.

 

[Michael A. Terrell]

"David L. Jones" wrote:

On Sep 26, 1:58 pm, "Phil Allison" <philalli...@tpg.com.au> wrote:
"David L. Jones"



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).

** 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 !!!

When all you have is a hammer, everything looks like a nail I guess!

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.

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.

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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There are two kinds of people on this earth:
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[Phil Allison]

"Franc Zabkar"

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.

** 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_rsProduct=89&i=prodsub&parent=HWARE&cat=BANANAPLGJCK&getDetails=


Why ????

Cos it plugs straight into this:

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

Ouch !!!



..... Phil