Latest depth camera stuff again !! New shielded wiring to come along


Electri-Cal
 

First off, I got a refund on the other underwater video cam yesterday.  It did not have the zoom lens as I wanted, and the screen was slightly damaged in shipping.  I keep it, so I can give it away which is better than a throwing it out, later this coming year most likely at a show.   New one from another source with ZOOM video will be here before boating season, good on that but slow China delivery.  Cost is $40., vs, $82,or more in US, sooo, in winter no contest.  New one will also have removable pickup, so I can take it inside, or have backup remote pickups for different uses. 

Docking, or fishing, or lost underwater gear searching come to mind.  Yes, the water needs to be clear, but new one has 8 -bright led and dimmable lights, plus a camera with chip slot chip built in, for underwater looking around.  Where did the sunken homes get to, the giant Salmon or Sturgeon in the Siuslaw --  or those darn pilings upstream of Toledo, that I hit  ???  I might even try threading the needle at east Dexter on a good day.

While I'm here, I added a 50 ft. roll of four shielded 18 ga. wires as upgraded instrument wiring, with the well grounded shield cover to be put in Surprise when the weather warms.  The electric drive throws off my depth finder picture over 1 mph.  Might not help the above camera either.  So, when done all essential electrics will be rewired inside shielded cabling. As an afterthought, I'm looking for a split shielding to cover depth finder factory sensor cabling.  All this is a grade A pain to do, but a good idea with all the electronics now coming along.  Probably need to call Bob Larkin or Myles Tweete on this subject, but I think the decent size wire will make this install robust enough.  Wish I could get the boat inside the garage for this, but gotta love the propane heater and wall tarp  !!

Days getting along, so me too,   Cal










Myles Twete
 

Shielding is nice but overrated.  If I could do shielding or something else, I’d rather implement twisted pairs on critical lines.

Fundamentally, what you want is signal integrity.

And to understand how best to achieve that requires an understanding of the noise source(s).

Too often I’ve worked for companies and engineers that don’t understand this and either don’t shield anything or shield without considering the alternatives or where to tie the shield.

 

Common things that destroy signal integrity include:

·       External EMI noise (e.g. electric or magnetic or e-m fields)---attention to routing, protection from noise sources helps here (twisted pair wiring and shields help here)

·       Current noise (e.g. due to ground loops---improper use of shields often cause these!)

I could go on…

 

Anyway, even the most seasoned electrical engineers don’t really appreciate the importance and nuances involved in this.  At one contract job I had, I was asked to develop a test fixture and procedure to test new DCDC converter “bricks” before they get installed onto a circuit board assembly.  The veteran ‘tech’ who had been testing these for years said that these things were suddenly failing right and left.  So I listened, then looked at the 20-year old design of the circuit and the specs on the DCDC.  Well, it turns out that the original design of the circuit (again, deployed now for decades) ignored the manufacturer’s safety instructions to ONLY connect one of 3 ground inputs to the external ground as the very sensitive circuitry connected all 3 internally and any external connections would cause ground loops and could blow the device.  Well, the client’s design grounded ALL 3 of these externally.

And so, my impression of what was happening was this ‘tech’ was suddenly testing these more recklessly than he had done in the past and ‘zapping’ these DCDCs due to this design flaw---had he been testing them this same way 2 decades ago, they’d have discovered the flaw---it’s best to fail early.

 

Anyway Cal, email me any info and I can give you my thoughts.

 

FWIW-

 

-Myles T

 

From: oregoncoots@groups.io [mailto:oregoncoots@groups.io] On Behalf Of Electri-Cal
Sent: Wednesday, November 25, 2020 8:52 AM
To: oregoncoots@groups.io
Subject: [oregoncoots] Latest depth camera stuff again !! New shielded wiring to come along

 

First off, I got a refund on the other underwater video cam yesterday.  It did not have the zoom lens as I wanted, and the screen was slightly damaged in shipping.  I keep it, so I can give it away which is better than a throwing it out, later this coming year most likely at a show.   New one from another source with ZOOM video will be here before boating season, good on that but slow China delivery.  Cost is $40., vs, $82,or more in US, sooo, in winter no contest.  New one will also have removable pickup, so I can take it inside, or have backup remote pickups for different uses. 

Docking, or fishing, or lost underwater gear searching come to mind.  Yes, the water needs to be clear, but new one has 8 -bright led and dimmable lights, plus a camera with chip slot chip built in, for underwater looking around.  Where did the sunken homes get to, the giant Salmon or Sturgeon in the Siuslaw --  or those darn pilings upstream of Toledo, that I hit  ???  I might even try threading the needle at east Dexter on a good day.

While I'm here, I added a 50 ft. roll of four shielded 18 ga. wires as upgraded instrument wiring, with the well grounded shield cover to be put in Surprise when the weather warms.  The electric drive throws off my depth finder picture over 1 mph.  Might not help the above camera either.  So, when done all essential electrics will be rewired inside shielded cabling. As an afterthought, I'm looking for a split shielding to cover depth finder factory sensor cabling.  All this is a grade A pain to do, but a good idea with all the electronics now coming along.  Probably need to call Bob Larkin or Myles Tweete on this subject, but I think the decent size wire will make this install robust enough.  Wish I could get the boat inside the garage for this, but gotta love the propane heater and wall tarp  !!

Days getting along, so me too,   Cal