Connector considerations

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KW1252
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Connector considerations

Post by KW1252 »

There has been a little concern with the connector of choice. Thus far, three options have been brought up:

D-sub connector
Pros
Very common
Very easy to obtain
Very cheap
Fair number of pin configurations

Cons:
Not very sturdy mechanically
No protection against elements
Must use several pins for large currents
Tough to solder reliably (especially triple rows), suitable crimp tool is expensive

Ribbon connector (Centronics connector, scsi connector)

Pros:
Slightly greater current cpacity than D-sub
Much more mechanically sound (pins are supported by the connector chassis)
Easy to obtain
Inexpensive
relatively high density

cons:
Not as common as D-sub
not protected against elements
No connector keying
still pretty bothersome to work with

Ampseal connectors

Pros:
Waterproof
High temp ratio
Easy to assemble
mating locks
reliable
high current capacity
Sturdy
Keyed

Cons:
Questionable availability in small numbers
Pricey (in range of 20-30 USD]
slightly bulky

Deutsch DRC connectors:
Weatherproof
High temp range
Easy to assemble
mating locks
reliable
high current capacity
sturdy
keyed

cons:
Questionable availability in small numbers
pricey
slightly bulky

In practice, the last two options are far superior, but more expensive and in practice require a deal through automotive electronics manufacturer, or a considerable bulk buy from the manufacturer and possibly a business ID.

There is not a similar problem with data connectors though. USB is USB, and the most common CAN connector is DE-9, so those shall be used.
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Fred
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Re: Connector considerations

Post by Fred »

At first, we need to concentrate on a simple, cheap, easy to build system thats mostly available in the local poorly stocked retail electronics shop for most people. Hence at first at least, db connectors for diy setups are the way to go at least for now.

specifically :
db25 male - ignition and spare outputs
db25 female - injection and spare outputs
db15hd male - standard inputs and spare inputs
db15hd female - standard inputs and spare inputs
db15 (ld) - standard inputs and spare inputs
db9 built into the board for budget comms and firmware loading
usb type B socket with pc to usb to uart to uart to MCU for higher reliability and speed comms and firmware loading (higher cost, hence optional)

There are multiple reasons for going this way.

Later when the project is off the ground and more and different types of people want to build these things, different designs can be built with more expensive connectors designed into the board.

As it stands the db connectors and a euro case will be provided for in a neat package, but there would be nothing stopping someone from either running short wires to a different connector in a different case, or redesigning and posting a board layout for a different plug and printing some.

Here is some proof that the DB connectors are up to the task :

This one is an "ultra stable oscillator" that was sent into space and used a db15 connector :

Image

This one explains itself :

Image

My thoughts are that if they are reliable to send into space for critical components then they are good enough for an in cabin device in a car too. Other devices have used db's in cars and had good reliability in the past. I realise that space = no moisture and no vibrations, but still, its a long way away if something goes wrong unmanned ;-)

Other options will be considered later for less experimental more environmentally resilient designs.

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Re: Connector considerations

Post by Fred »

Sorry, I didn't see your mention of CAN over db9 (yes, you are correct with the de9, but old habits die hard). Although that is a fairly standard connector for that, its HUGE for a device that carries no current and has only three pins. There has to be a better choice for that. I don't know what it is.

I should also add that for a power connector I intend to use an XLR connector, as these are very robust and carry plenty of current (25amp/pin I think).

I can't over emphasize the importance at least in these early stages for making the design maximally accessible to the general public. And therefore easy and cheap to get parts for.

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slacker.cam
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Re: Connector considerations

Post by slacker.cam »

Tyco/AMP offer a number of sealed multi-pin connectors aimed at the automotive sector. They're summarised here: Link.

I've worked with both the Ampseal (M&W CDI's) and Super Seal (Motec ECU's) ranges and I personally like the Super Seal variety the best as they are very easy to insert and remove the pins in (they have a single locking tab which locks/unlocks all of the pins easily), and they are available in some quite nice configurations. There is a 60 pin option that breaks the pins into 2 separate lots that i think would be nice to keep high current outputs away from noise sensitive inputs. Pricing information is not readily available unfortunately but i imagine it would be similar to the Ampseal range.

Obviously the best option for prototyping will be something cheap and easy to get hold of like the DB connectors but if i were to design a proper board in the future then it will definitely have a good sealed connector.
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Fred
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Re: Connector considerations

Post by Fred »

It should be noted that some people attempting to use Amp seal connectors in harsh environments have had failures due to leakage. It is my observation that it is vastly better to have a connector that will not resist moisture and to do something about that in another respect than to think that the connector will resist moisture and then have it leak and let you down.

Just a thought.

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ababkin
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Re: Connector considerations

Post by ababkin »

here is what i acquired for WBO sensor

Image
Image
Image
Image

both male+female cost me around $10 (female was on sale for $4 from $14)
these are impressive quality (not cheap surplus crap)
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Re: Connector considerations

Post by Fred »

Yes, I've used amphenol/cannon stuff myself for a few things, the three pin version is what I was intending to use for the first iteration design. but if 5 is common around the place, that is even better! :-)
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ababkin
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Re: Connector considerations

Post by ababkin »

Admin wrote:Yes, I've used amphenol/cannon stuff myself for a few things, the three pin version is what I was intending to use for the first iteration design. but if 5 is common around the place, that is even better! :-)
actually they told me in the store that 5 pin is not common at all (hence the sale) but 3pin is much more popular

EDIT: this is the store i got them from: http://www.e-sonic.com/acc/home.aspx
They have pretty sweet price breaks at 10 units (for any connector). It would be a very good idea for us to decide on connectors, then get a group buy for the members = cheaper for everyone + someone can send them out such way to reduce/eliminate the import tax, etc.

EDIT2: LOL, i just noticed, on the images you've attached, the DB connectors flew into space in 1985. Thats over 20 yrs ago. I bet they've also 'endowed' that machinery with a 1.4Mb (no less) floppy drive ;)
Last edited by ababkin on Wed Mar 12, 2008 1:26 am, edited 1 time in total.
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Fred
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Re: Connector considerations

Post by Fred »

Hence the IF :-)

3 pin is used extensively in commercial audio gear you see :-)
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whitenoise
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Re: Connector considerations

Post by whitenoise »

This is probably decided already, but here's what I'm using on my MS:

Image

They're Tyco Multilock connectors with the following part numbers:

Male - 26+22+16 pins - 174518-7 - About $5 each

Female - 26 pins - 174516-6 - About $1.25 each

22 pins - 174515-6 - About $1.20 each

They came standard on many 90's Japanese vehicles. Can be bought in single quantities from onlinecomponents.com and newark electronics in the US. DIYAutotune uses them on the MSPNP as well.

Of course they're still not as convenient as the DB because you still have to crimp contacts into the female connector side.
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