Intermittent open circuit in 3.5mm co-ax connectors

[L.A.T.]

Something else to add to the sum of human knowledge.
Because I had them already , I have used 3.5mm co-axial mono connectors to
join vavious bits and pieces in my P.I.R. to camera setups.
In a scheme where everything depends on presence or absence of a voltage
this was a Bad Move. The contact between these line-plugs and line-sockets
is dodgy: a light tap at the point where they are connected is enough to
interrupt the earth/shield contact. The signal part of the plug is gripped
by a little spring inside the socket, and probably doesn't ever lose
contact, but the outer earth/shield plug merely slides into a cylindrical
hole. It looks and feels as if it is a snug fit but can, as I said,
momentarily lose continuity if moved even slightly. In my scheme, such an
interrupted connection is equivalent to the end of one camera trigger and
the beginning of another trigger. I believe that sometimes it has occurred
that there was no initial contact at all and that valid signals from the
P.I.R. were never sensed by the camera.
On the weekend I will replace all these connectors with RCA connectors.

 

[Phil Allison]

"L.A.T."

Something else to add to the sum of human knowledge.

** Huh ??

Dont' kid youself, pal.

Because I had them already , I have used 3.5mm co-axial mono connectors to
join vavious bits and pieces in my P.I.R. to camera setups.
In a scheme where everything depends on presence or absence of a voltage
this was a Bad Move. The contact between these line-plugs and line-sockets
is dodgy: a light tap at the point where they are connected is enough to
interrupt the earth/shield contact.

** Line sockets for jack plugs are notorioulsy unreliable, even in 6.3 mm
size.

The signal part of the plug is gripped by a little spring inside the
socket, and probably doesn't ever lose contact, but the outer earth/shield
plug merely slides into a cylindrical hole. It looks and feels as if it is
a snug fit but can, as I said, momentarily lose continuity if moved even
slightly.

** Panel mount sockets do not suffer from the same problem nearly so much.

Trick is, there must be only *one* tip contact and it must have a strong
spring action PLSU have enough travel to push hard into the notch in the
tip.

This way, the shaft of the plug is offset in the barrel of the socket and
makes good contact.

On the weekend I will replace all these connectors with RCA connectors.

** Yep - RCAs are normally a tight pressure fit for both inner and outer
conductors.

The plastic covers tend to disintegrate easily, so it is worth the extra to
get all metal ones.

Cover them with heatshrink if touching is an issue.



...... Phil

 

[Sylvia Else]

Phil Allison wrote:

"L.A.T."
Something else to add to the sum of human knowledge.

** Huh ??

Dont' kid youself, pal.

Because I had them already , I have used 3.5mm co-axial mono connectors to
join vavious bits and pieces in my P.I.R. to camera setups.
In a scheme where everything depends on presence or absence of a voltage
this was a Bad Move. The contact between these line-plugs and line-sockets
is dodgy: a light tap at the point where they are connected is enough to
interrupt the earth/shield contact.


** Line sockets for jack plugs are notorioulsy unreliable, even in 6.3 mm
size.

I hate jack-plugs and sockets. I don't think I've ever had one that
didn't cause trouble at some point. I'd happily see them expunged from
the sum of human knowledge.

Sylvia.

 

[Mr.T]

"L.A.T." <tt92@ispdr.net.au> wrote in message
news:u2e3m.2298$ze1.103@news-server.bigpond.net.au...

On the weekend I will replace all these connectors with RCA connectors.

So upgrading from total shite to slightly less shite then

MrT.

 

[Trevor Wilson]

"L.A.T." <tt92@ispdr.net.au> wrote in message
news:u2e3m.2298$ze1.103@news-server.bigpond.net.au...

Something else to add to the sum of human knowledge.
Because I had them already , I have used 3.5mm co-axial mono connectors to
join vavious bits and pieces in my P.I.R. to camera setups.
In a scheme where everything depends on presence or absence of a voltage
this was a Bad Move. The contact between these line-plugs and line-sockets
is dodgy: a light tap at the point where they are connected is enough to
interrupt the earth/shield contact. The signal part of the plug is gripped
by a little spring inside the socket, and probably doesn't ever lose
contact, but the outer earth/shield plug merely slides into a cylindrical
hole. It looks and feels as if it is a snug fit but can, as I said,
momentarily lose continuity if moved even slightly. In my scheme, such an
interrupted connection is equivalent to the end of one camera trigger and
the beginning of another trigger. I believe that sometimes it has occurred
that there was no initial contact at all and that valid signals from the
P.I.R. were never sensed by the camera.
On the weekend I will replace all these connectors with RCA connectors.

**Or you could get sensible and use something decent. Provided there is ZERO
chance that anyone will ever mistake them for audio connectors, you could
use XLR connectors. They're tough, reliable and locking. They're also well
priced. I like the Neutrik branded ones but there are others.


--
Trevor Wilson
www.rageaudio.com.au

 

[Phil Allison]

"Trevor Wilson"
"L.A.T."

On the weekend I will replace all these connectors with RCA connectors.

**Or you could get sensible and use something decent. Provided there is
ZERO chance that anyone will ever mistake them for audio connectors, you
could use XLR connectors. They're tough, reliable and locking. They're
also well priced. I like the Neutrik branded ones but there are others.

** Mini XLR is a possible option too.

Even DC connectors do not have the issues mini jack plugs do.



..... Phil

 

[L.A.T.]

snip>

Trick is, there must be only *one* tip contact and it must have a strong
spring action PLSU have enough travel to push hard into the notch in the
tip.

This way, the shaft of the plug is offset in the barrel of the socket and
makes good contact.

Makes a lot of sense. The little ones I had (Jaycar) had a double spring.

 

[Adrian Jansen]

L.A.T. wrote:

Something else to add to the sum of human knowledge.
Because I had them already , I have used 3.5mm co-axial mono connectors to
join vavious bits and pieces in my P.I.R. to camera setups.
In a scheme where everything depends on presence or absence of a voltage
this was a Bad Move. The contact between these line-plugs and line-sockets
is dodgy: a light tap at the point where they are connected is enough to
interrupt the earth/shield contact. The signal part of the plug is gripped
by a little spring inside the socket, and probably doesn't ever lose
contact, but the outer earth/shield plug merely slides into a cylindrical
hole. It looks and feels as if it is a snug fit but can, as I said,
momentarily lose continuity if moved even slightly. In my scheme, such an
interrupted connection is equivalent to the end of one camera trigger and
the beginning of another trigger. I believe that sometimes it has occurred
that there was no initial contact at all and that valid signals from the
P.I.R. were never sensed by the camera.
On the weekend I will replace all these connectors with RCA connectors.


RCA connectors have the same sort of problems. Use the mini XLR type

connectors from Jaycar cat nos PP1910 and PP1912 or similar.

--
Regards,

Adrian Jansen adrianjansen at internode dot on dot net
Design Engineer J & K Micro Systems
Microcomputer solutions for industrial control
Note reply address is invalid, convert address above to machine form.

 

[terryc]

On Sat, 04 Jul 2009 10:20:40 +1000, Adrian Jansen wrote:

RCA connectors have the same sort of problems. Use the mini XLR type
connectors from Jaycar cat nos PP1910 and PP1912 or similar.

Will they go intermittent on a very shaky table?


Background; one of my first DIY projects was a project to charge up ni-
cads from a bicyle hub generator during the day to give better/
consistentbicycle lights of a night time.

Firstly I tried 6.5mm plug and socket and had flashing lights. <mutter>.
Next I tried RCA and same problem, but they just popped off. In the end I
went to hard wired which has its own problems, mainly really water/
weather prrof switches are very expensive and hard wired didn't easily
allow plug swap bypassing.







--
Great advances in Debian Linux; post a bug report and get spam in three
days.







--
Great advances in Debian Linux; post a bug report and get spam in three
days.

 

[Adrian Jansen]

terryc wrote:

On Sat, 04 Jul 2009 10:20:40 +1000, Adrian Jansen wrote:


RCA connectors have the same sort of problems. Use the mini XLR type
connectors from Jaycar cat nos PP1910 and PP1912 or similar.

Will they go intermittent on a very shaky table?


Background; one of my first DIY projects was a project to charge up ni-
cads from a bicyle hub generator during the day to give better/
consistentbicycle lights of a night time.

Firstly I tried 6.5mm plug and socket and had flashing lights. <mutter>.
Next I tried RCA and same problem, but they just popped off. In the end I
went to hard wired which has its own problems, mainly really water/
weather prrof switches are very expensive and hard wired didn't easily
allow plug swap bypassing.







I dont know for sure. But the contacts look good, and at least they are

3 of the same type of contact, not a pin and a loose fitting sleeve
that relies on side pressure to make contact. Maybe that means they all
fail equally :-( Full tech specs on any consumer item are almost
impossible to get.

It is also possible to insert an O ring on the outer sleeve, so they can
be made fairly waterproof.

--
Regards,

Adrian Jansen adrianjansen at internode dot on dot net
Design Engineer J & K Micro Systems
Microcomputer solutions for industrial control
Note reply address is invalid, convert address above to machine form.