How to configure shielded wire?

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Healey3000
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How to configure shielded wire?

Post by Healey3000 »

Hi,

Crank and Cam Hall sensors benefit from shielding on their cables, as has been clarified. However, there are a few different ways one can configure the shield; is one better than the other (in all cases, shield is connected to analog ground at MS3):

Run a single coax cable on the output pin of the sensor to MS3 with unshielded power and ground wires
Run a shielded twisted pair for signal and ground
Run a shielded twisted triad for all conductors within the shield

Thanks!
slow_hemi6
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Re: How to configure shielded wire?

Post by slow_hemi6 »

I look at it this way. Garbage in = Garbage out.
Use a shield to screen all 3. I use 4 core shielded mic cable and just use 3 of the 4 cores.
Find the Manuals up top under Quick links: Manuals. :RTFM:
Cheers Luke
walterclark1
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Re: How to configure shielded wire?

Post by walterclark1 »

I always connect shields at one end only - in the case of sensors for the MS, at the MS end. This prevents ground loops, which in my experience in car and home audio are much more of a problem than RF interference. Of course this eliminates the possible use of coax, but I prefer shielded twisted pair anyway for its better differential mode rejection - even in single ended applications such as where one wire is connected to analog ground in the Megasquirt.
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Healey3000
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Re: How to configure shielded wire?

Post by Healey3000 »

slow_hemi6 wrote:I look at it this way. Garbage in = Garbage out.
Use a shield to screen all 3. I use 4 core shielded mic cable and just use 3 of the 4 cores.
Thanks, Luke. Can you share the specific part number/source for the cable. Lots of choices out there so I want to be sure I use something that is known to work.
Healey3000
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Re: How to configure shielded wire?

Post by Healey3000 »

walterclark1 wrote:I always connect shields at one end only - in the case of sensors for the MS, at the MS end. This prevents ground loops, which in my experience in car and home audio are much more of a problem than RF interference. Of course this eliminates the possible use of coax, but I prefer shielded twisted pair anyway for its better differential mode rejection - even in single ended applications such as where one wire is connected to analog ground in the Megasquirt.
Hi,

Proper grounding is pretty ingrained in me from years of audio design. Coax works well for analog signals, granted, the runs are relatively short and the environment isn't as hostile. I recall trying an unshielded twisted pair for preamp level signals once and it was a mess. Had to go back to coax.
slow_hemi6
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Re: How to configure shielded wire?

Post by slow_hemi6 »

Find the Manuals up top under Quick links: Manuals. :RTFM:
Cheers Luke
dcg9381
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Re: How to configure shielded wire?

Post by dcg9381 »

walterclark1 wrote:I always connect shields at one end only - in the case of sensors for the MS, at the MS end.
Where should they be terminated? I understand that you don't want to connect them to the common ground.
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slow_hemi6
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Re: How to configure shielded wire?

Post by slow_hemi6 »

Find the Manuals up top under Quick links: Manuals. :RTFM:
Cheers Luke
walterclark1
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Re: How to configure shielded wire?

Post by walterclark1 »

Any one of the pins on the V3/3/57 board connector that is labeled ground and is otherwise unused is fine for the shield. I have connected each of mine to a different pin between pins 8 and 13 but if I run out of available spots I will tie 2-3 shields to one pin. Note that I dont tap into any existing ground wires such as those connecting the engine, ignition, injectors, or sensors ("analog ground"). I go directly to the connector at the V3 board.

The reference linked by slow_hemi6 shows an example of this with the crank position sensor.
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dcg9381
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Re: How to configure shielded wire?

Post by dcg9381 »

Thanks.. I get it now. It's common connectivity to MS, but not the same as 14-19, which are tied to chassis ground.
Currently running: (SnSE 029v MT 2.25 )
1981 Toyota truck, draw-through, supercharged (GM TBI) - fuel only
1988 Toyota 4runner, 22RE plug-and-play integration MSnSE
1988 toyota 4runner, 22re turbo MSnSE
1988 Toyota 4runner, 2rz turbo in-progress... http://www.2rzturbo.net/
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