COPIS MEG and VR3 Deco

**Monkey** · 3rd January 2007, 22:26

Quote: (Originally Posted by henckell)

One way of looking at it could be from an economical point of view. A COPIS plus HH is not much more expensive than a standard Meg plus a VR3, and it will have more capabilities and features.

If/When the Apecs 3 comes out it will probaly be the most expensive variant.

and correct me if I am wrong but would that not give me a backup head if the HH takes a dump?

fredrik · 3rd January 2007, 22:30

Quote: (Originally Posted by Blomman)

What is the point in buying a "KISS-style rebreather" just to rebuild it to a eCCR? It sounds to me that you have bought the wrong rebreather from the beginning. It would be more logical to buy a standard MEG and then use your VR3 to keep track of deco.

// Blomman

I can think of severel reasons.

If it shows that rebreather wasn´t your bag, this is a cheaper "buy and try"
Constant oxygene massflow, Kiss, Copies, rEvo is a easy way to learn rebrether diving and to understand the gas flow before getting more advanced.
If you like and/or trust everything about the Meg except the electronics, then it will be cheaper to use the Copies than the "Regular" to build on.
Hammerhead got integrated deco computer.

***jradomski*** · 3rd January 2007, 23:21

Quote: (Originally Posted by bgpartri)

It's not quite that simple. For example, if one of the devices has some other failure mode like a short battery life, having a second device that has a long battery life can increase overall redundancy.

It is important to look at various failure modes to determine whether redundancy is increased or decreased.

For most sensor failures like current limited sensors, wet sensor faces, wet sensor connectors, wet banana plugs, and broken sensor wires, isolation provides no benefit. All of the connected devices will be affected.

Even for a shorted device, it has to fail in a particular way to make all of the op-amps attack all of the sensors. I've never seen this in practise, but it could happen.

With rebreathers that only have one display, redundancy is increased unless you believe that cut wires that end up shorted is the most common failure.

Although resistor networks were common with analogue electronics, rnodern designs like the Inspiration, Meg and KISS use op-amp isolation as does the Shearwater.

If in the end you decide that shorted wires is what you are most worried about, the Shearwater works just fine stand-alone or on a fourth sensor.

Bruce You are overlooking the most likely failure when using fischer connectors.. a flooded connector.. This shorts the leads and onloy isolation resistors at the cells weill prevent this from altering the other cells..

also what about a cut or nicked cable... again the only thing that works is isolation resistors at the cells.. High Isolation op amps are good for isolating the electronics from each other but does no good in protecting the other controllers from 2 forseeable failures..

If you had all the electronics near each other and the leads to the sensors could be short and protected, opamp only isolation isnt bad.. but when the signals must be carried by a cable, and especially through a connector, not so good..

A secod paralleled device can help for a bad battery or something that crashes due to a software bug or maybe a miscalibration (but this one should be caught on the surface)

It doest take alot to add in some isolation for the cable..

The meg Isolates it in the Head (and in the same enclosure), there is no chance that an outside force would effect the sensors between handsets so a resister network isnt needed, although it could be added..

When the electronics are away from the cells this is a totally different condition..

I agree using the shearwater as a 4th cell is a good idea, adding a few resitors also would make it a good idea paralleling it.. (assuming you keep the load correct otherwise you alter the accuracy of the temperature compensating ckt in the cell - this I consider a small error especially if the loop is calibrated around 20c-30c).

bgpartri · 4th January 2007, 03:16

Joe,

The fact is that resistor isolation networks aren't used by the KISS, APECS, COPIS, Inspiration, VR3, or HS-Explorer electronics. The Shearwater is an add-on product. Since the COPIS Meg uses op-amp isolation, the Shearwater has to as well if it is going to be compatible. It's the only way they can co-exist.

I'm not against resistor networks. Implemented properly, so they protect the cable from the sensor connector to the electronics, they can be useful.

That's the beauty of choice. If you don't like Fischer connectors, don't use them. If you want to parallel the sensors, use a 4th sensor, or use a stand-alone computer, you can do that. Each user can evaluate their situation and choose accordingly.

***jradomski*** · 4th January 2007, 04:22

Quote: (Originally Posted by bgpartri)

Joe,

The fact is that resistor isolation networks aren't used by the KISS, APECS, COPIS, Inspiration, VR3, or HS-Explorer electronics. The Shearwater is an add-on product. Since the COPIS Meg uses op-amp isolation, the Shearwater has to as well if it is going to be compatible. It's the only way they can co-exist.

I'm not against resistor networks. Implemented properly, so they protect the cable from the sensor connector to the electronics, they can be useful.

That's the beauty of choice. If you don't like Fischer connectors, don't use them. If you want to parallel the sensors, use a 4th sensor, or use a stand-alone computer, you can do that. Each user can evaluate their situation and choose accordingly.

Bruce,
Te high impedience of the input stage of the op amp do not preclude the addition of a resistor isolation at the sensors.. This increases impedience is small compared to the imput impedience of the op amp..

I don;t know the COPIS electronics on what they preent to the cell, but I'll ssume 10k load since thats whats presented on the APECs..

I dont know what you present acroos the cell, and if you make it different if its going to be a stand alone or of its meant to be an addition (The inspiration electronics present the wrong load across the cells - Its not matched for the temp ckt but the error is small)

Lets say you want the load to be small so you add a 100k ((if you added 10k you slightly mismatch the temp compensating ckt for the r22d- I have run temp sweeps on cells using different loads, with the correct loading I usually see about a 2% max (full scale) error due to temp (other have told me they have seen 5% erors), the wrong applied impedience adds another 1-2% on average) across the inputs, adding another ~2.5k at the cell is not going to have an effect (100k case) on the readings, on the 10k case it can slightly improve temp response.. Its a win win.. easy to add and no down side..

On the copis making a simple adapter with a molex plug, header and a few resistors would allow isolation of both and no permanent changes... You could even isolate one side.. leaving the added computer/monitor thats couldn;t effect the origina;, but the original could effect the additional..

The fischer connectors work if you take care of them.. I ran the HH for several years without any problem dives, but I know plenty of others that flooded their connectors multiple times.. With a hard plumbed, water block cable and potted electronics, the resister network becomes much less needed..

I'm not claiming to be a Mr. Know It all, but I firmly believe risks should be minimized if possible.. In my mind something that takes a very simple modification/addition is a no brainer..

You have come out with what appears to be a solid product and I hope that you do well with it..

cameron · 4th January 2007, 08:47

Question here...

Say you had the shearwater computer and HUD instaled in parallel as per the website. If you were to have a fischer fail or the cable cut, would all three displays be affected on BOTH the computer and the HUD?

What would happen if you lost one sensor? Could the display for all three cells for both units be affected?

Or is this a big MABEY?

remember.. big 'ol layman here...

***jradomski*** · 4th January 2007, 10:05

Quote: (Originally Posted by cameron)

Question here...

Say you had the shearwater computer and HUD instaled in parallel as per the website. If you were to have a fischer fail or the cable cut, would all three displays be affected on BOTH the computer and the HUD?

What would happen if you lost one sensor? Could the display for all three cells for both units be affected?

Or is this a big MABEY?

remember.. big 'ol layman here...

First question, Are you using solenoid control or not.. This makes a difference..

If yes, a flooded fischer connecter would pass several volts to the cells every time the controller tries to fire the solenoid.. A cell outputs 7mv to about 200mv... What do you think the other device would read each time the solenoid was fired.. There are also other possibilities here as well..

I can speak from what I have seen on the HH.. A flooded fischer connector maxed out the AD converter in the hadset (that connector flooded) and displayed the max po2, but due to isolation, the other handset was un effected.... when the solenoid wasnt firing the po2 readings (on the flooded handset connector) were not accurate (usually lower than actual) but if you were conservative it would be enough to keep a breathable loop.. on a paralled system I would expect to see the same on both devices. on The HH primary a high voltage could be generated by the signal for firing the solenoid, on the secondary a high voltage would be generated by the signals going to the head and eventually the HUD and vibrator.. Each system will have its own pitfalls.

I am not trying to scare anyone or discourage the purchase of any product.. Just point out a potential failure mode so an honest evaluation can be made and if specific precautions should be looked at.. Do away with the fischer connectors and any other connectors (hard plumb) and the only thing that would be of concern is a damaged cable which is much less likely than flooding the fischer connector.. Which most people would consider an acceptable risk (low probability)..

The only reason I brought this up in the first place is the frequency that I have seen fischer connectors flooded..

Search the archives on the various web boards and see how many of the HH isues/complaints were from flooded connectors during a dive..

How bad a flooded connector effects the system also depends on what other signals are in the cable and the proximity of these signals (pin arrangement) to each other.. There is no one answer here....

bgpartri · 4th January 2007, 14:18

The Shearwater is not available with a solenoid and a Fischer connector.

Mark Chase · 4th January 2007, 15:48

Quote: (Originally Posted by bgpartri)

The Shearwater is not available with a solenoid and a Fischer connector.

Yes but does this concern adding a computer to the cells of a unit that does have a solenoid?

The only Fischer connector on my rig will be the one between the Shearweater and the cable leading to the cells. I don't expect that cable to have ANY voltage in it except for the cell out put voltage.

If the Fischer connector on the Shearwater failed and flooded shorting out all 7pins how would this affect the readings on my primary system?

I cant see an issue unless the voltage from the internal battery of the Shearwater somehow shorts and connects to the Fischer connector sending battery voltage down the line.

Id like to add when using my VR3 via the Uri HUD I suffered two or three flooded Fischer connector issues and one where the Fischer lock failed and it fell out altogether. The end result was absolutely nothing happened. The primary hand sets carried on working fine without even a flicker.

ATB

Mark Chase

RonMicjan · 4th January 2007, 18:48

So, again, what it comes down to is: fischer connectors suck! at least for underwater applications. I will never buy another unit that uses them.

If you must have your dive computer tied into your loop, do so with a fourth cell that is independent of your stock cells and have it hardwired. this provides redundancy of cells and complete isolation of circuits.

3rd January 2007, 22:26	#31 (permalink)
Monkey Supporting Member Current Rebreather/s: Megalodon Other Rebreather/s: Join Date: Dec 2006 Location: Lauderdale By The Sea Florida Posts: 338	Re: COPIS MEG and VR3 Deco Quote: (Originally Posted by henckell) One way of looking at it could be from an economical point of view. A COPIS plus HH is not much more expensive than a standard Meg plus a VR3, and it will have more capabilities and features. If/When the Apecs 3 comes out it will probaly be the most expensive variant. and correct me if I am wrong but would that not give me a backup head if the HH takes a dump?
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3rd January 2007, 22:30	#32 (permalink)
fredrik Rekodeko. Sweden Current Rebreather/s: Classic Kiss Other CCR Other Rebreather/s: Other CCR Join Date: Apr 2005 Location: Sweden Posts: 190	Re: COPIS MEG and VR3 Deco Quote: (Originally Posted by Blomman) What is the point in buying a "KISS-style rebreather" just to rebuild it to a eCCR? It sounds to me that you have bought the wrong rebreather from the beginning. It would be more logical to buy a standard MEG and then use your VR3 to keep track of deco. // Blomman I can think of severel reasons. If it shows that rebreather wasn´t your bag, this is a cheaper "buy and try" Constant oxygene massflow, Kiss, Copies, rEvo is a easy way to learn rebrether diving and to understand the gas flow before getting more advanced. If you like and/or trust everything about the Meg except the electronics, then it will be cheaper to use the Copies than the "Regular" to build on. Hammerhead got integrated deco computer.
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3rd January 2007, 23:21	#33 (permalink)
*jradomski* Moderator Current Rebreather/s: Inspiration Classic Sport Kiss Optima rEvo Other CCR Other Rebreather/s: Inspiration Vision Evolution Megalodon Classic Kiss rEvo Other CCR Join Date: Mar 2005 Location: "Da" Bronx Posts: 3,113	Re: COPIS MEG and VR3 Deco Quote: (Originally Posted by bgpartri) It's not quite that simple. For example, if one of the devices has some other failure mode like a short battery life, having a second device that has a long battery life can increase overall redundancy. It is important to look at various failure modes to determine whether redundancy is increased or decreased. For most sensor failures like current limited sensors, wet sensor faces, wet sensor connectors, wet banana plugs, and broken sensor wires, isolation provides no benefit. All of the connected devices will be affected. Even for a shorted device, it has to fail in a particular way to make all of the op-amps attack all of the sensors. I've never seen this in practise, but it could happen. With rebreathers that only have one display, redundancy is increased unless you believe that cut wires that end up shorted is the most common failure. Although resistor networks were common with analogue electronics, rnodern designs like the Inspiration, Meg and KISS use op-amp isolation as does the Shearwater. If in the end you decide that shorted wires is what you are most worried about, the Shearwater works just fine stand-alone or on a fourth sensor. Bruce You are overlooking the most likely failure when using fischer connectors.. a flooded connector.. This shorts the leads and onloy isolation resistors at the cells weill prevent this from altering the other cells.. also what about a cut or nicked cable... again the only thing that works is isolation resistors at the cells.. High Isolation op amps are good for isolating the electronics from each other but does no good in protecting the other controllers from 2 forseeable failures.. If you had all the electronics near each other and the leads to the sensors could be short and protected, opamp only isolation isnt bad.. but when the signals must be carried by a cable, and especially through a connector, not so good.. A secod paralleled device can help for a bad battery or something that crashes due to a software bug or maybe a miscalibration (but this one should be caught on the surface) It doest take alot to add in some isolation for the cable.. The meg Isolates it in the Head (and in the same enclosure), there is no chance that an outside force would effect the sensors between handsets so a resister network isnt needed, although it could be added.. When the electronics are away from the cells this is a totally different condition.. I agree using the shearwater as a 4th cell is a good idea, adding a few resitors also would make it a good idea paralleling it.. (assuming you keep the load correct otherwise you alter the accuracy of the temperature compensating ckt in the cell - this I consider a small error especially if the loop is calibrated around 20c-30c). __________________ Joe Radomski CCR Trimix Instructor Trainer ANDI Instructor Trainer Director #10 All posts are personal opinions and DO NOT reflect any affiliated agency unless specifically stated. Last edited by jradomski : 4th January 2007 at 00:13.
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4th January 2007, 03:16	#34 (permalink)
bgpartri CEO-Shearwater Current Rebreather/s: Megalodon Other Rebreather/s: Inspiration Classic Sport Kiss Classic Kiss Titan Join Date: Apr 2005 Location: Vancouver, Canada Posts: 423	Re: COPIS MEG and VR3 Deco Joe, The fact is that resistor isolation networks aren't used by the KISS, APECS, COPIS, Inspiration, VR3, or HS-Explorer electronics. The Shearwater is an add-on product. Since the COPIS Meg uses op-amp isolation, the Shearwater has to as well if it is going to be compatible. It's the only way they can co-exist. I'm not against resistor networks. Implemented properly, so they protect the cable from the sensor connector to the electronics, they can be useful. That's the beauty of choice. If you don't like Fischer connectors, don't use them. If you want to parallel the sensors, use a 4th sensor, or use a stand-alone computer, you can do that. Each user can evaluate their situation and choose accordingly. __________________ http://www.shearwaterresearch.com Good judgment comes from experience. Experience comes from bad judgment.
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4th January 2007, 04:22	#35 (permalink)
*jradomski* Moderator Current Rebreather/s: Inspiration Classic Sport Kiss Optima rEvo Other CCR Other Rebreather/s: Inspiration Vision Evolution Megalodon Classic Kiss rEvo Other CCR Join Date: Mar 2005 Location: "Da" Bronx Posts: 3,113	Re: COPIS MEG and VR3 Deco Quote: (Originally Posted by bgpartri) Joe, The fact is that resistor isolation networks aren't used by the KISS, APECS, COPIS, Inspiration, VR3, or HS-Explorer electronics. The Shearwater is an add-on product. Since the COPIS Meg uses op-amp isolation, the Shearwater has to as well if it is going to be compatible. It's the only way they can co-exist. I'm not against resistor networks. Implemented properly, so they protect the cable from the sensor connector to the electronics, they can be useful. That's the beauty of choice. If you don't like Fischer connectors, don't use them. If you want to parallel the sensors, use a 4th sensor, or use a stand-alone computer, you can do that. Each user can evaluate their situation and choose accordingly. Bruce, Te high impedience of the input stage of the op amp do not preclude the addition of a resistor isolation at the sensors.. This increases impedience is small compared to the imput impedience of the op amp.. I don;t know the COPIS electronics on what they preent to the cell, but I'll ssume 10k load since thats whats presented on the APECs.. I dont know what you present acroos the cell, and if you make it different if its going to be a stand alone or of its meant to be an addition (The inspiration electronics present the wrong load across the cells - Its not matched for the temp ckt but the error is small) Lets say you want the load to be small so you add a 100k ((if you added 10k you slightly mismatch the temp compensating ckt for the r22d- I have run temp sweeps on cells using different loads, with the correct loading I usually see about a 2% max (full scale) error due to temp (other have told me they have seen 5% erors), the wrong applied impedience adds another 1-2% on average) across the inputs, adding another ~2.5k at the cell is not going to have an effect (100k case) on the readings, on the 10k case it can slightly improve temp response.. Its a win win.. easy to add and no down side.. On the copis making a simple adapter with a molex plug, header and a few resistors would allow isolation of both and no permanent changes... You could even isolate one side.. leaving the added computer/monitor thats couldn;t effect the origina;, but the original could effect the additional.. The fischer connectors work if you take care of them.. I ran the HH for several years without any problem dives, but I know plenty of others that flooded their connectors multiple times.. With a hard plumbed, water block cable and potted electronics, the resister network becomes much less needed.. I'm not claiming to be a Mr. Know It all, but I firmly believe risks should be minimized if possible.. In my mind something that takes a very simple modification/addition is a no brainer.. You have come out with what appears to be a solid product and I hope that you do well with it.. __________________ Joe Radomski CCR Trimix Instructor Trainer ANDI Instructor Trainer Director #10 All posts are personal opinions and DO NOT reflect any affiliated agency unless specifically stated. Last edited by jradomski : 4th January 2007 at 04:25.
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4th January 2007, 08:47	#36 (permalink)
cameron RBW Member Current Rebreather/s: Classic Kiss Other Rebreather/s: Join Date: Apr 2005 Location: Toronto, Ontario, Canada Posts: 262	Re: COPIS MEG and VR3 Deco Question here... Say you had the shearwater computer and HUD instaled in parallel as per the website. If you were to have a fischer fail or the cable cut, would all three displays be affected on BOTH the computer and the HUD? What would happen if you lost one sensor? Could the display for all three cells for both units be affected? Or is this a big MABEY? remember.. big 'ol layman here... Last edited by cameron : 4th January 2007 at 08:49.
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4th January 2007, 10:05	#37 (permalink)
*jradomski* Moderator Current Rebreather/s: Inspiration Classic Sport Kiss Optima rEvo Other CCR Other Rebreather/s: Inspiration Vision Evolution Megalodon Classic Kiss rEvo Other CCR Join Date: Mar 2005 Location: "Da" Bronx Posts: 3,113	Re: COPIS MEG and VR3 Deco Quote: (Originally Posted by cameron) Question here... Say you had the shearwater computer and HUD instaled in parallel as per the website. If you were to have a fischer fail or the cable cut, would all three displays be affected on BOTH the computer and the HUD? What would happen if you lost one sensor? Could the display for all three cells for both units be affected? Or is this a big MABEY? remember.. big 'ol layman here... First question, Are you using solenoid control or not.. This makes a difference.. If yes, a flooded fischer connecter would pass several volts to the cells every time the controller tries to fire the solenoid.. A cell outputs 7mv to about 200mv... What do you think the other device would read each time the solenoid was fired.. There are also other possibilities here as well.. I can speak from what I have seen on the HH.. A flooded fischer connector maxed out the AD converter in the hadset (that connector flooded) and displayed the max po2, but due to isolation, the other handset was un effected.... when the solenoid wasnt firing the po2 readings (on the flooded handset connector) were not accurate (usually lower than actual) but if you were conservative it would be enough to keep a breathable loop.. on a paralled system I would expect to see the same on both devices. on The HH primary a high voltage could be generated by the signal for firing the solenoid, on the secondary a high voltage would be generated by the signals going to the head and eventually the HUD and vibrator.. Each system will have its own pitfalls. I am not trying to scare anyone or discourage the purchase of any product.. Just point out a potential failure mode so an honest evaluation can be made and if specific precautions should be looked at.. Do away with the fischer connectors and any other connectors (hard plumb) and the only thing that would be of concern is a damaged cable which is much less likely than flooding the fischer connector.. Which most people would consider an acceptable risk (low probability).. The only reason I brought this up in the first place is the frequency that I have seen fischer connectors flooded.. Search the archives on the various web boards and see how many of the HH isues/complaints were from flooded connectors during a dive.. How bad a flooded connector effects the system also depends on what other signals are in the cable and the proximity of these signals (pin arrangement) to each other.. There is no one answer here.... __________________ Joe Radomski CCR Trimix Instructor Trainer ANDI Instructor Trainer Director #10 All posts are personal opinions and DO NOT reflect any affiliated agency unless specifically stated.
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4th January 2007, 14:18	#38 (permalink)
bgpartri CEO-Shearwater Current Rebreather/s: Megalodon Other Rebreather/s: Inspiration Classic Sport Kiss Classic Kiss Titan Join Date: Apr 2005 Location: Vancouver, Canada Posts: 423	Re: COPIS MEG and VR3 Deco The Shearwater is not available with a solenoid and a Fischer connector. __________________ http://www.shearwaterresearch.com Good judgment comes from experience. Experience comes from bad judgment.
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4th January 2007, 15:48	#39 (permalink)
Mark Chase RBW Member Current Rebreather/s: Classic Kiss Other Rebreather/s: Inspiration Classic Join Date: Jan 2005 Location: Kent Posts: 2,858	Re: COPIS MEG and VR3 Deco Quote: (Originally Posted by bgpartri) The Shearwater is not available with a solenoid and a Fischer connector. Yes but does this concern adding a computer to the cells of a unit that does have a solenoid? The only Fischer connector on my rig will be the one between the Shearweater and the cable leading to the cells. I don't expect that cable to have ANY voltage in it except for the cell out put voltage. If the Fischer connector on the Shearwater failed and flooded shorting out all 7pins how would this affect the readings on my primary system? I cant see an issue unless the voltage from the internal battery of the Shearwater somehow shorts and connects to the Fischer connector sending battery voltage down the line. Id like to add when using my VR3 via the Uri HUD I suffered two or three flooded Fischer connector issues and one where the Fischer lock failed and it fell out altogether. The end result was absolutely nothing happened. The primary hand sets carried on working fine without even a flicker. ATB Mark Chase __________________ See my "Doing It Chasey" video where I'm locked into a padded room, naked, with two ball bearings and within an Hour, I manage to lose one and break the other!!! Kevin Juergensen 16/11/08 [/quote]
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4th January 2007, 18:48	#40 (permalink)
RonMicjan Cap Ron scourge of the NW Current Rebreather/s: Megalodon Dolphin Home Build Other Rebreather/s: Sport Kiss Classic Kiss Dolphin Home Build Join Date: Feb 2005 Location: Cape Disapointment, The Graveyard of the Pacific Posts: 1,120	Re: COPIS MEG and VR3 Deco So, again, what it comes down to is: fischer connectors suck! at least for underwater applications. I will never buy another unit that uses them. If you must have your dive computer tied into your loop, do so with a fourth cell that is independent of your stock cells and have it hardwired. this provides redundancy of cells and complete isolation of circuits. __________________ Marine rescue, towing and salvage. Interfering with natural selection since 1983. www.tmishop.com Diving bits etc. www.seatowpdx.com The Summer Job
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