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RPM Sensor

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Mike Welch

Joined: 13 Feb 2011
Posts: 272

Posted: Wed Jun 20, 2012 9:46 am Post subject: RPM Sensor

Jim, Bob, list members,



  Thank you for your responses.  My initial request was brief, in an attempt to pay respect to the Matronics rules, since obviously my needs are not aviation related.  They are, however, electronic in nature, and I, for one, always enjoy every electronic post, aviation or not, because I always enjoy learning from the best!!  Since Bob suggests bringing the subject onto the this list,  I hope those that read this topic are able to glean some electronic knowledge and, or share their skills.

  So, with an understanding this topic is not aero-electric, but yet it certainly is electronic, so it may help educate some of us electronic novices, here goes;

  My recently submitted, patent-pending invention (UNDERWATER GOLD PROCESSOR) is essentially an underwater, remotely powered Bobcat style, ocean floor, skidloader/material sifter.  ALL functions are hydraulically powered, and the means (pump, controls, etc) remain onboard the (floating) dredge, and at the control of the operator.  Hydraulic lines, air lines, electric cords, etc, etc, combine in conjunction with the suction hose, that goes down to the machine, at an approx. depth between 10 to 30 feet.  (although 100' depth may be a consideration)





  My invention is essentially a "tractor" (sort of), that clears big boulders out of the way, scoops up tremendous amounts of sea floor dirt, classifies the dirt to discard the rocks and unwanted gravel, and sends the remaining gold ore concentrate up to the dredge in phenomenal amounts.  The dredge then processes this gold ore in traditional sluicebox methods.  The present method, known as 'state of the art',  in use today is a diver walking along the seafloor with a suction hose.  This diver and the dredge operator frequently pull in 1/2 oz/day.   My machine replaces this diver, and is anticipated to produce at least 20 to 50 times (or MUCH more) his daily gold tally.

 Initial calculations, with my machine progressing forward at an easy, and likely "1/2 mph", suggest processing 4 cubic yards of sea floor dirt PER MINUTE.  Since much of the coast off 

of Nome has gold assayed at .01 oz AU per cu/yd, that equates close to 4/100 oz./minute ($72/min), or, on a productive day, 10 hrs  X  60 minutes/hr  X  .04 oz/min    =  24 oz AU per day.   These calculations are for the "personal" size machine.  The commercial model is off the charts! (30 cu/yds per minute  {that's an ounce every three minutes).  As with many things, the bigger the machine, the better it operates.

    My invention does not require a human operator controlling it "hands-on" underwater, but rather, the dredge operator still need to be able to monitor the various implement functions (rotating shaft's speed)from the boat.  Of all the various rotating parts, two are of primary importance.  The first one is sort of a rototiller style rock remover, and the second function is the revolving scoops conveyor.  Although underwater video cameras are expected to assist the operator in monitoring the machine's efficiency, through practice and experience, he would be greatly augmented by knowing how fast the two primary implements are turning.  "Extremely precise" readings are not likely needed.  For instance, once the operator gets used to working the machine, he may find that 215 rpm seems to work well with most seafloor regions.  So, when he sets himself up for the beginning of his daily run, he can set the speed of that at a "proven-to-be-successful" 215 rpms, or something close to that.  Obviously, rpms in the range of 200-230 are probably 'close enough' to watch the action, and he can make adjustments as needed.

  I am convinced my invention can, and will, make some people very wealthy.  There are unique features about it that I have not discussed so far.  

  My intention is to either license it to a fabrication plant, or maybe even begin making them myself, (if I could find an investor).  I just put together a website this past weekend, and is a "work-in progress".  (I don't have anything on it yet)  However, I am building a 1/4 scale, fully functioning model, too, and am about 60% finished with the model.  I will video the model in action, and post it on my website as soon as I can.  My wife just conceded she "may" actually agree to me building the very first one, and go use it!  If I were to build one, I'd need those rpm circuits figured out, for sure.

If I were ever to fabricate them on a commercial level, the monitoring circuits would need to be in a "plug & play" package.  

  Shaft rpm's would be needed for 5 separate functions.  Underwater salt environment.  20' average depth.   rpm ranges around 0-

300.  I'd prefer digital accuracy.   

  Thank to all for their tolerance to this non-aviation subject.  Please feel free to contribute any suggestions regarding the rpm circuitry.  However,  if anyone is interested in further discussions regarding my invention itself, please contact me OFF-LIST, as appropriate.

Mike Welch 

  



On Jun 20, 2012, at 8:52 AM, Jim Hausch wrote:

[quote]

Sounds like a neat project.  My last "out of the ordinary" project was DARPA funded.  It was to test the idea for an automated winch to deploy a soldier on a parachute from an autonomous jetski.  The idea is that the jetski would pull him to altitude and then he would disconnect and glide to shore or "wherever".  I worked on the winch controls.  It is certainly more fun than the usual factory applications I work on.

Your application just might beat that one out for "cool factor with the ability to actually make some money!"  

At what depth do the sensors need to survive?

It sounds like the displays are to help the operator of the tractor know what his manipulation of the proportional valves are doing.  If you think he might ever actuate the motors to turn very slowly, we might want to display RPM with at least one digit to the right of the decimal point and want more "data" than one pulse per rev.

Are there any other system readouts that would be of value to the operator (pressures, levels, depths, etc)?  I ask because if you get up to more than 4 individual meters, looking at a single larger programmable display starts to make more sense.

Let me know the answer to at least the depth question and I will work first on the simple RPM display.

Jim Hausch

 Power/mation

 Cell - 414-254-1857

 Office - 262-408-6146 On Jun 20, 2012 8:25 AM, "Michael Welch" <mdnanwelch7(at)hotmail.com (mdnanwelch7(at)hotmail.com)> wrote: 	  Quote: 	
		   Hi Jim,



  Thank you for your response and interest in my post regarding an rpm meter.

This reply is also off Matronics, mostly because my need is non-aero, but it certainly is 

 electric. 

  So, unless we get sort of an invite from Bob, I think it is courtesy to stay off-list.  So, I thank you.

  Now, to answer your questions, but first, some background info on why I need the rpm circuits;  

   For the last 3+ months, I have been working on an invention.  It is in the field of gold prospecting, 

and very specifically, underwater offshore gold prospecting.  About a month ago, I submitted my 

 completed application for a "non-provisional patent" to the US Patent & Trademark Office (USPTO).

  My invention replaces the typical underwater diver (lugging an 8" suction hose).  It is essentially an

 underwater remotely operated tractor.  My calculations predict between 20 to 50 times 

his productivity. (picture the comparison between a guy digging a ditch with a shovel, and an excavator)

   At any rate, my invention relies on hydraulic motors to perform its sundry motions.  I don't have any

detailed designs of the particular shafts, but if I knew what the rpm circuit(s) would look like, I would

 make accommodations as necessary.  In all likeliness, the shafts(s) will be simple rotating axles,

where an attachment (magnet?) can be mounted to give a rotational pulse.  The environment is

underwater, (sea water).

 



  See below for additional answers adjacent to the question.

Thanks for your help,

Mike Welch



On Jun 20, 2012, at 5:52 AM, Jim Hausch wrote:

 

 	  Quote: 	
		  Mike,

I am a lurker on Aero-Electric.  I noticed your post (and Bob's reply) looking for some RPM meters.  I work in factory automation, so this is right up our alley.  I am sending this from my work email so if we start a conversation I have the record "where i need it".  

  



Bob (CC'd on this message), 

If you would prefer I recap this on the Matronics list, please let me know.

Mike, 

What is on the shaft that the sensor will sense? Is there a key, flat, or other feature we can sense with a simple inductive prox?  If you have a drawing or picture of the shaft, please send it along.  (assume a simple 1 1/2" dia., full-length woodruff keyed, rotating steel shaft, in an underwater environment)  
How many shafts need to be measured simultaneously?  (two separate,independent circuits, at least, with two displays.  However, depending on the design, I could use as many as 6) 
How large would you like the display to be?  (if gauges are individual, 2" or so, each.  If multiple displays per single screen, maybe 1/4" to 3/8" high numbers) 
What sort of environment does the system need to live in?  (sensors live in salt water, displays live in dry, above water, console)
What is the available power (115 from a wall outlet, or is there an existing panel with lower voltage AC or even a 24Vdc supply in it)?  (the dredge (support boat) will have any form of necessary power.  115 ac will be available, BUT, due to the water hazards, I would greatly prefer to stay with something no more dangerous than 24Vdc.  12Vdc would be my most preferred, but 24Vdc would be fine if a circuit operated better with it) 

 

Let me know and I can give you a proposal.

Regards,Jim Hausch

Power/mation

Cell - [url=tel:414-254-1857]414-254-1857[/url]

 Office - [url=tel:262-408-6146]262-408-6146[/url]

 Interesting Information and Random Updates



 



 	






	


 [b]

nuckolls.bob(at)aeroelect
Guest

Posted: Thu Jun 21, 2012 2:55 pm Post subject: RPM Sensor

At 12:43 PM 6/20/2012, you wrote:

 Jim, Bob, list members,



   Thank you for your responses.  My initial request was brief, in an attempt to pay respect to the Matronics rules, since obviously my needs are not aviation related.  They are, however, electronic in nature, and I, for one, always enjoy every electronic post, aviation or not, because I always enjoy learning from the best!!  Since Bob suggests bringing the subject onto the this list,  I hope those that read this topic are able to glean some electronic knowledge and, or share their skills.



   So, with an understanding this topic is not aero-electric, but yet it certainly is electronic, so it may help educate some of us electronic novices, here goes;

   

   <snip>



  Okay, 100' water pressure (50 PSI is no sweat). Digital display with say 1 RPM resolution and 0.5 RPM accuracy at 300 RPM maximum. Jim was asking about how the shaft speed to be measured was made available for electronic inspection . . . it could be as simple as counting passages of a woodruff key. In your case, the relatively slow speed combined with 1 part in 300 resolution probably precludes looking at one-count-per-rev signal sources . . . jitter in spacing of the counting edges can make an otherwise smoothly rotating shaft appear to be unstable.



  What length and diameter of the shaft is available to mount say a disk of magnets to be counted? Jim may have other ideas to offer but my first thought was based on a hall switch watching an array of 10 magnets. This could easily be made water proof to those pressures. Jim may be aware of an off the shelf, programmable instrument that would convert 300 counts per minute into a 300.0 RPM display. Such a device could be built too . . . the electronics is easy, PACKAGING is the hard part . . . especially for salt water service.

  Is this machine to be processor or computer guided? Would you want a tachometer to computer interface capability to know the current RPM?

  Except for the salt-water under pressure requirement and decidedly non-aircraft style motor shaft, this tachometer display task is not unlike that for aircraft applications. After selecting and interfacing a suitable sensor, one needs to know the 'scale factor' (pulses-per-revolution) from the sensor so that the readout can be appropriately configured.

    Bob . . .    [quote][b]

Mike Welch

Joined: 13 Feb 2011
Posts: 272

Posted: Thu Jun 21, 2012 3:54 pm Post subject: RPM Sensor

Bob,



  See below for the answers to your questions.

 	  Quote: 	
		  

  Okay, 100' water pressure (50 PSI is no sweat). Digital display with say 1 RPM resolution and 0.5 RPM accuracy at 300 RPM maximum. Jim was asking about how the shaft speed to be measured was made available for electronic inspection . . . it could be as simple as counting passages of a woodruff key. In your case, the relatively slow speed combined with 1 part in 300 resolution probably precludes looking at one-count-per-rev signal sources . . . jitter in spacing of the counting edges can make an otherwise smoothly rotating shaft appear to be unstable.



	
             Regarding the pressure needed to work well, good (50 psi).  The digital display with 1 rpm and .5rpm accuracy sounds perfect.  

             I anticipate a splined shaft of approx. 1.75" diameter (for sprockets).  If I need to add an extra couple of inches to allow for a rotating

            wheel, that would be no problem at all!!  Are we talking about roughly 10 strong magnets, say...on a 6" diameter wheel?  If so, that

            would be VERY easy to fabricate a fiberglass disc, encapsulating said magnets near the rim.  

 	  Quote: 	
		  

  What length and diameter of the shaft is available to mount say a disk of magnets to be counted? Jim may have other ideas to offer but my first thought was based on a hall switch watching an array of 10 magnets. (Mine, too, and this would be an easy task to build)

This could easily be made water proof to those pressures. Jim may be aware of an off the shelf, programmable instrument that would convert 300 counts per minute into a 300.0 RPM display. Such a device could be built too . . . the electronics is easy, PACKAGING is the hard part . . . especially for salt water service.



	
                 Other than the sensor to read those rotating magnets, what else would 

                 need to be underwater?  The sensor?  That should be a sealed unit, no?

                 Other than the 10-magnet disc and sensor, all other item are topside.

                 The gauge/display unit would be in a water-tite console.

 	  Quote: 	
		    Is this machine to be processor or computer guided? Would you want a tachometer to computer interface capability to know the current RPM?

  Except for the salt-water under pressure requirement and decidedly non-aircraft style motor shaft, this tachometer display task is not unlike that for aircraft applications. After selecting and interfacing a suitable sensor, one needs to know the 'scale factor' (pulses-per-revolution) from the sensor so that the readout can be appropriately configured.

	
                No, not computer guided or driven.  Hands on operation, but requiring only occasional

                adjustment, from information from the various rpm gauges. 

                I think 10 pulses per rev is plenty good resolution.  If we can read these magnets by way

               of a familiar sensor you have in mind, I'll make a parts order tomorrow, and get going making the disc.

               Bob, back a year ago when we were talking neodymium magnets & Hall Effect sensors

               for an airspeed indicator, I bought a handful of 1/8" x 1/8" x 1/2".  They be small, but they be

               purdy strong!  Will they work?  Any ideas for the sensor?

[quote]  

  Bob . . .     	  Quote: 	
		  



href="http://www.matronics.com/Navigator?AeroElectric-List">http://www.matronics.com/Navigator?AeroElectric-List

href="http://forums.matronics.com/">http://forums.matronics.com

href="http://www.matronics.com/contribution">http://www.matronics.com/contribution



	


[b]

Mike Welch

Joined: 13 Feb 2011
Posts: 272

Posted: Thu Jun 21, 2012 4:02 pm Post subject: RPM Sensor

Bob,

  Is there any way we can make these display units work with our design?  I REALLY like their products,

I have two of them in my plane.  One for turbo boost (from a MAP sensor), and one of their EGT gauges

and senders.  Nice stuff!

http://www.auberins.com/index.php?main_page=product_info&cPath=16&products_id=212

 The displays units are easy to mount, and are bright in sunlight.

Mike Welch



 [quote][b]

Mike Welch

Joined: 13 Feb 2011
Posts: 272

Posted: Fri Jun 22, 2012 5:24 am Post subject: RPM Sensor

Mornin' Jim,



    I think you've found the sensor we're looking for!  By any chance, do you or Bob know if the little

neodymium magnets I have on hand will work with this one?  (they are 1/8" x 1/8" x 1/2" long).  If

they're too small, I get can bigger ones.

  When you say "5mm or less from a mild steel target", are you talking about the magnets, or will

literally 'any' steel work?  I envision whatever 'target' we end up with will be 100% encapsulated

into the fiberglass disc.  Making a bracket to have the sensor maintain a <5mm distance is no

problem at all.  I'd shoot for 2mm, and can't see why that would be an easy task.

  I still haven't understood what it is that we are calling targets.  Can these be Neodymium magnets?  

Some guidance would be appreciated, please.

  Aside from "the targets, the sensor, and the gauge itself.....we would still need some sort of circuitry

to interrogate the pulses, right?

  I'm looking forward to seeing your display(s), and your 'other suggestion.  Thanks,

Mike Welch

On Jun 22, 2012, at 7:11 AM, Jim Hausch wrote:

[quote]I've found some proximity sensors:



BI 5-P18-AP6/S139-S90 

[url=http://www.turck-usa.com/illustrations/M1660350%20(sheet_1).pdf]http://www.turck-usa.com/illustrations/M1660350%20(sheet_1).pdf[/url] 



This example only has a 2 meter cable, but longer are available

 Special housing with PUR cable.

oil and seawater resistant to 500 meters (1641 ft)and 725 PSI. 

I have displays similar to what you posted.  I have another suggestion, too.

 I will put some stuff together for you this weekend.  That sensor needs to be 5mm or less from a mild-steel target.  Less to SS.  Think about how you can give that sensor 4 targets per rev and I think you will be happy with the system performance.

 Regards,Jim Hausch



 

 



On Wed, Jun 20, 2012 at 5:48 PM, Jim Hausch <jim.hausch(at)powermation.com (jim.hausch(at)powermation.com)> wrote:

 	  Quote: 	
		    OK, thanks.  I can refer to this in my files now as the Dsog project... perfect.



I understand the response re hyd flow monitoring.  Thanks for the info.  I will continue to look for the 12 or 24Vdc submersible solution.

   Regards,Jim Hausch

Power/mation

Cell - [url=tel:414-254-1857]414-254-1857[/url]

Office - [url=tel:262-408-6146]262-408-6146[/url]

  



Interesting Information and Random Updates

 

 

On Wed, Jun 20, 2012 at 4:09 PM, Michael Welch <mdnanwelch7(at)hotmail.com (mdnanwelch7(at)hotmail.com)> wrote:

   	  Quote: 	
		   Hi Jim,



  A)  I don't think the hydraulic flow, or even the pressure will be very useful, especially due to the varying loads in use.  I think what it is infinitely more useful is the implement's rotational

   speed, which can be tapped off of a drive axle or motor shaft.

2)  Yes, I have a name for my invention.  It's called the Dsog.  See my attached company logo;

Mike Welch

   



<Test3.gif>



On Jun 20, 2012, at 3:59 PM, Jim Hausch wrote:

   

 	  Quote: 	
		  Great.  Thanks.  I am no hydraulics expert, but would monitoring flow rate on the hyd lines feeding the motors be an accurate way to monitor speed, or do these motors have built-in bypasses to protect from overload?  I only mention this because it would keep the speed sensors above the surface....    Regards,Jim Hausch

Power/mation

Cell - [url=tel:414-254-1857]414-254-1857[/url]

Office - [url=tel:262-408-6146]262-408-6146[/url]

   



Interesting Information and Random Updates

 

 



On Wed, Jun 20, 2012 at 3:54 PM, Michael Welch <mdnanwelch7(at)hotmail.com (mdnanwelch7(at)hotmail.com)> wrote:

 	  Quote: 	
		      Jim,



  The 1 1/2" shaft is for the 'real' model.  The scale model is not intended to be that detailed such

that it would would require monitors.

    



Mike



On Jun 20, 2012, at 3:32 PM, Jim Hausch wrote:



 	  Quote: 	
		  The 1.5" shaft diameter spec from a previous email - is that for both the 1/4 scale model and the actual unit?  If not, what is the shaft diameter you need today?  

    Regards,Jim Hausch

 Power/mation

Cell - [url=tel:414-254-1857]414-254-1857[/url]

Office - [url=tel:262-408-6146]262-408-6146[/url]

    



Interesting Information and Random Updates

 

 



On Wed, Jun 20, 2012 at 12:43 PM, Michael Welch <mdnanwelch7(at)hotmail.com (mdnanwelch7(at)hotmail.com)> wrote:

 	  Quote: 	
		       Jim, Bob, list members,



  Thank you for your responses.  My initial request was brief, in an attempt to pay respect to the Matronics rules, since obviously my needs are not aviation related.  They are, however, electronic in nature, and I, for one, always enjoy every electronic post, aviation or not, because I always enjoy learning from the best!!  Since Bob suggests bringing the subject onto the this list,  I hope those that read this topic are able to glean some electronic knowledge and, or share their skills.

     



  So, with an understanding this topic is not aero-electric, but yet it certainly is electronic, so it may help educate some of us electronic novices, here goes;

     



  My recently submitted, patent-pending invention (UNDERWATER GOLD PROCESSOR) is essentially an underwater, remotely powered Bobcat style, ocean floor, skidloader/material sifter.  ALL functions are hydraulically powered, and the means (pump, controls, etc) remain onboard the (floating) dredge, and at the control of the operator.  Hydraulic lines, air lines, electric cords, etc, etc, combine in conjunction with the suction hose, that goes down to the machine, at an approx. depth between 10 to 30 feet.  (although 100' depth may be a consideration)

     



  My invention is essentially a "tractor" (sort of), that clears big boulders out of the way, scoops up tremendous amounts of sea floor dirt, classifies the dirt to discard the rocks and unwanted gravel, and sends the remaining gold ore concentrate up to the dredge in phenomenal amounts.  The dredge then processes this gold ore in traditional sluicebox methods.  The present method, known as 'state of the art',  in use today is a diver walking along the seafloor with a suction hose.  This diver and the dredge operator frequently pull in 1/2 oz/day.   My machine replaces this diver, and is anticipated to produce at least 20 to 50 times (or MUCH more) his daily gold tally.

     



 Initial calculations, with my machine progressing forward at an easy, and likely "1/2 mph", suggest processing 4 cubic yards of sea floor dirt PER MINUTE.  Since much of the coast off 

     of Nome has gold assayed at .01 oz AU per cu/yd, that equates close to 4/100 oz./minute ($72/min), or, on a productive day, 10 hrs  X  60 minutes/hr  X  .04 oz/min    =  24 oz AU per day.   These calculations are for the "personal" size machine.  The commercial model is off the charts! (30 cu/yds per minute  {that's an ounce every three minutes).  As with many things, the bigger the machine, the better it operates.

     



    My invention does not require a human operator controlling it "hands-on" underwater, but rather, the dredge operator still need to be able to monitor the various implement functions (rotating shaft's speed)from the boat.  Of all the various rotating parts, two are of primary importance.  The first one is sort of a rototiller style rock remover, and the second function is the revolving scoops conveyor.  Although underwater video cameras are expected to assist the operator in monitoring the machine's efficiency, through practice and experience, he would be greatly augmented by knowing how fast the two primary implements are turning.  "Extremely precise" readings are not likely needed.  For instance, once the operator gets used to working the machine, he may find that 215 rpm seems to work well with most seafloor regions.  So, when he sets himself up for the beginning of his daily run, he can set the speed of that at a "proven-to-be-successful" 215 rpms, or something close to that.  Obviously, rpms in the range of 200-230 are probably 'close enough' to watch the action, and he can make adjustments as needed.

     



  I am convinced my invention can, and will, make some people very wealthy.  There are unique features about it that I have not discussed so far.  

     



  My intention is to either license it to a fabrication plant, or maybe even begin making them myself, (if I could find an investor).  I just put together a website this past weekend, and is a "work-in progress".  (I don't have anything on it yet)  However, I am building a 1/4 scale, fully functioning model, too, and am about 60% finished with the model.  I will video the model in action, and post it on my website as soon as I can.  My wife just conceded she "may" actually agree to me building the very first one, and go use it!  If I were to build one, I'd need those rpm circuits figured out, for sure.

     If I were ever to fabricate them on a commercial level, the monitoring circuits would need to be in a "plug & play" package.  

  Shaft rpm's would be needed for 5 separate functions.  Underwater salt environment.  20' average depth.   rpm ranges around 0-

     300.  I'd prefer digital accuracy.   

  Thank to all for their tolerance to this non-aviation subject.  Please feel free to contribute any suggestions regarding the rpm circuitry.  However,  if anyone is interested in further discussions regarding my invention itself, please contact me OFF-LIST, as appropriate.

     



Mike Welch 

  



On Jun 20, 2012, at 8:52 AM, Jim Hausch wrote:



 	  Quote: 	
		  

    Sounds like a neat project.  My last "out of the ordinary" project was DARPA funded.  It was to test the idea for an automated winch to deploy a soldier on a parachute from an autonomous jetski.  The idea is that the jetski would pull him to altitude and then he would disconnect and glide to shore or "wherever".  I worked on the winch controls.  It is certainly more fun than the usual factory applications I work on.

Your application just might beat that one out for "cool factor with the ability to actually make some money!"  

At what depth do the sensors need to survive?

It sounds like the displays are to help the operator of the tractor know what his manipulation of the proportional valves are doing.  If you think he might ever actuate the motors to turn very slowly, we might want to display RPM with at least one digit to the right of the decimal point and want more "data" than one pulse per rev.

Are there any other system readouts that would be of value to the operator (pressures, levels, depths, etc)?  I ask because if you get up to more than 4 individual meters, looking at a single larger programmable display starts to make more sense.

Let me know the answer to at least the depth question and I will work first on the simple RPM display.

Jim Hausch

 Power/mation

 Cell - [url=tel:414-254-1857]414-254-1857[/url]

 Office - mdnanwelch7(at)hotmail.com (mdnanwelch7(at)hotmail.com)> wrote: 	  Quote: 	
		        Hi Jim,



  Thank you for your response and interest in my post regarding an rpm meter.

This reply is also off Matronics, mostly because my need is non-aero, but it certainly is 

      electric. 

  So, unless we get sort of an invite from Bob, I think it is courtesy to stay off-list.  So, I thank you.

  Now, to answer your questions, but first, some background info on why I need the rpm circuits;  

        For the last 3+ months, I have been working on an invention.  It is in the field of gold prospecting, 

and very specifically, underwater offshore gold prospecting.  About a month ago, I submitted my 

      completed application for a "non-provisional patent" to the US Patent & Trademark Office (USPTO).

  My invention replaces the typical underwater diver (lugging an 8" suction hose).  It is essentially an

      underwater remotely operated tractor.  My calculations predict between 20 to 50 times 

his productivity. (picture the comparison between a guy digging a ditch with a shovel, and an excavator)

        At any rate, my invention relies on hydraulic motors to perform its sundry motions.  I don't have any

detailed designs of the particular shafts, but if I knew what the rpm circuit(s) would look like, I would

      make accommodations as necessary.  In all likeliness, the shafts(s) will be simple rotating axles,

where an attachment (magnet?) can be mounted to give a rotational pulse.  The environment is

underwater, (sea water).

      



  See below for additional answers adjacent to the question.

Thanks for your help,

Mike Welch



On Jun 20, 2012, at 5:52 AM, Jim Hausch wrote:

      

 	  Quote: 	
		  Mike,

I am a lurker on Aero-Electric.  I noticed your post (and Bob's reply) looking for some RPM meters.  I work in factory automation, so this is right up our alley.  I am sending this from my work email so if we start a conversation I have the record "where i need it".  

       



Bob (CC'd on this message), 

If you would prefer I recap this on the Matronics list, please let me know.

Mike, 

What is on the shaft that the sensor will sense? Is there a key, flat, or other feature we can sense with a simple inductive prox?  If you have a drawing or picture of the shaft, please send it along.  (assume a simple 1 1/2" dia., full-length woodruff keyed, rotating steel shaft, in an underwater environment)       
How many shafts need to be measured simultaneously?  (two separate,independent circuits, at least, with two displays.  However, depending on the design, I could use as many as 6)      
How large would you like the display to be?  (if gauges are individual, 2" or so, each.  If multiple displays per single screen, maybe 1/4" to 3/8" high numbers)      
What sort of environment does the system need to live in?  (sensors live in salt water, displays live in dry, above water, console)
What is the available power (115 from a wall outlet, or is there an existing panel with lower voltage AC or even a 24Vdc supply in it)?  (the dredge (support boat) will have any form of necessary power.  115 ac will be available, BUT, due to the water hazards, I would greatly prefer to stay with something no more dangerous than 24Vdc.  12Vdc would be my most preferred, but 24Vdc would be fine if a circuit operated better with it)      

 

Let me know and I can give you a proposal.

Regards,Jim Hausch

Power/mation

Cell - [url=tel:414-254-1857]414-254-1857[/url]

      Office - [url=tel:262-408-6146]262-408-6146[/url]

 Interesting Information and Random Updates



 



 	






	


 	




	


 	




	


 	




	






 	




 

 [b]

nuckolls.bob(at)aeroelect
Guest

Posted: Fri Jun 22, 2012 5:36 am Post subject: RPM Sensor

Regarding the pressure needed to work well, good (50 psi).  The digital display with 1 rpm and .5rpm accuracy sounds perfect. I anticipate a splined shaft of approx. 1.75" diameter (for sprockets).  If I need to add an extra couple of inches to allow for a rotating wheel, that would be no problem at all!!  Are we talking about roughly 10 strong magnets, say...on a 6" diameter wheel?  If so, that would be VERY easy to fabricate a fiberglass disc, encapsulating said magnets near the rim.



   Doesn't need to be that "hoggy" except for general mechanical robustness. If the magnet disk is subject to being struck during normal ops, handling or maintenance then it needs to be shielded or perhaps enclosed. Diameter could be just large enough to fit over the shaft and leave room for mounting magnets. Sensor would be potted into a non-magnetic housing not unlike a pipe-threaded thermowell temperature sensor. This is one of thousands of Hall switches that could be considered to the task.



   http://tinyurl.com/77pmvke

 



 Other than the sensor to read those rotating magnets, what else would 

 need to be underwater?  The sensor?  That should be a sealed unit, no?

 Other than the 10-magnet disc and sensor, all other item are topside.

 The gauge/display unit would be in a water-tite console.



   Just the magnet disk and sensor.

 



 Is there any way we can make these display units work with our design?  I REALLY like their products, I have two of them in my plane.  One for turbo boost (from a MAP sensor), and one of their EGT gauges and senders.  Nice stuff!



  http://www.auberins.com/index.php?main_page=product_info&cPath=16&products_id=212

 

 The displays units are easy to mount, and are bright in sunlight.



   Sure, the counter seems to offer a customer programmed multiply by N divide by K feature for calibrating odd pulse-per-rev values into other units like rpm, fps, etc. But then, your 'operator' probably doesn't give a toot about RPM . . . you could simply display the speed counts raw and write an operator manual that suggests unitless values as opposed to RPM.

    Bob . . .    [quote][b]

Mike Welch

Joined: 13 Feb 2011
Posts: 272

Posted: Fri Jun 22, 2012 5:44 am Post subject: RPM Sensor

Hi Jim,



  Four targets is fine with me.  Can we count on say, a 6" diameter fiberglass disc, with four 

steel target, equally spaced near the outer edge, and a fixture that securely hold the 

sensor 2mm away from the rotating disc?

Mike



On Jun 22, 2012, at 8:30 AM, Jim Hausch wrote:

[quote]

This inductive proximity sensor does not use a magnet as a target.  SS or mild steel would work.  You could use an of the shelf gear or sprocket ant sense the teeth.  You just dont want the teeth too close together so the sensor can have an OFF condition between the ON conditions.  In the case of this sort of sensor, a "barrel diameter" between teeth is more than enough.

The datasheet shows the max switching freq.  Speed should not be a problem, but we can confirm once you tell me how many targets we have on the disk we will be sensing (such as how many teeth if you use a sprocket)

Jim [b]

Mike Welch

Joined: 13 Feb 2011
Posts: 272

Posted: Fri Jun 22, 2012 6:37 am Post subject: RPM Sensor

Bob,



 	  Quote: 	
		  "But then, your 'operator' probably doesn't give a tootabout RPM . . . you could simply display the speed countsraw and write an operator manual that suggests unitlessvalues as opposed to RPM."

	




        Exactly!! (to the above quote)  All our operator needs is a consistent and 

reasonably accurate reading, so that he/she can 'learn' what numbers do what.

       Yes, I can picture the sensor/wheel enclosed in a protective cover.  Too many

rough scenarios to not expect to protect it all under some sort of guard.

       Thanks for your expertise and help.  Jim said he has some more stuff he'll work

on this weekend.  I'll wait on him and see what he comes up with before I order any parts.

Best regard,

Mike





On Jun 22, 2012, at 8:35 AM, Robert L. Nuckolls, III wrote:

[quote]  Regarding the pressure needed to work well, good (50 psi).  The digital display with 1 rpm and .5rpm accuracy sounds perfect. I anticipate a splined shaft of approx. 1.75" diameter (for sprockets).  If I need to add an extra couple of inches to allow for a rotating wheel, that would be no problem at all!!  Are we talking about roughly 10 strong magnets, say...on a 6" diameter wheel?  If so, that would be VERY easy to fabricate a fiberglass disc, encapsulating said magnets near the rim.



   Doesn't need to be that "hoggy" except for general mechanical robustness. If the magnet disk is subject to being struck during normal ops, handling or maintenance then it needs to be shielded or perhaps enclosed. Diameter could be just large enough to fit over the shaft and leave room for mounting magnets. Sensor would be potted into a non-magnetic housing not unlike a pipe-threaded thermowell temperature sensor. This is one of thousands of Hall switches that could be considered to the task.



   http://tinyurl.com/77pmvke

 



 Other than the sensor to read those rotating magnets, what else would 

 need to be underwater?  The sensor?  That should be a sealed unit, no?

 Other than the 10-magnet disc and sensor, all other item are topside.

 The gauge/display unit would be in a water-tite console.



   Just the magnet disk and sensor.

 



 Is there any way we can make these display units work with our design?  I REALLY like their products, I have two of them in my plane.  One for turbo boost (from a MAP sensor), and one of their EGT gauges and senders.  Nice stuff!



  http://www.auberins.com/index.php?main_page=product_info&cPath=16&products_id=212

 

 The displays units are easy to mount, and are bright in sunlight.



   Sure, the counter seems to offer a customer programmed multiply by N divide by K feature for calibrating odd pulse-per-rev values into other units like rpm, fps, etc. But then, your 'operator' probably doesn't give a toot about RPM . . . you could simply display the speed counts raw and write an operator manual that suggests unitless values as opposed to RPM.



  

  Bob . . .     	  Quote: 	
		  



href="http://www.matronics.com/Navigator?AeroElectric-List">http://www.matronics.com/Navigator?AeroElectric-List

href="http://forums.matronics.com/">http://forums.matronics.com

href="http://www.matronics.com/contribution">http://www.matronics.com/contribution



	


[b]

nuckolls.bob(at)aeroelect
Guest

Posted: Fri Jun 22, 2012 6:46 am Post subject: RPM Sensor

 	  Quote: 	
		          Thanks for your expertise and help.  Jim said he has some more stuff he'll work

 on this weekend.  I'll wait on him and see what he comes up with before I order any parts. 	


    Sounds a like a plan. Thanks for the heads-up

    on those counters. That user programmable

    scale factor feature is slick.



 

   Bob . . .    [quote][b]

Mike Welch

Joined: 13 Feb 2011
Posts: 272

Posted: Fri Jun 22, 2012 7:12 am Post subject: RPM Sensor

Bob,



  Regarding Auber Instruments, I especially like the programmable relays that are included in them, too.

  On my EGT gauge, for instance, I have it set at 1200 deg F to switch on an adjustable fuel enrichment feature,

in conjunction with a activated LED flashing alarm, to let me know the circuit is active.

  Similar story with my boost gauge.  Since I ONLY want 6 psi max boost, and no more, I have the boost gauge's relay

activate a 19 LED alarm strobing flashing system.   It sort of looks like those mobile highway light signs that strobe

an arrow to change lanes.  Can't miss it.

Mike  





 

On Jun 22, 2012, at 9:44 AM, Robert L. Nuckolls, III wrote:

 	  Quote: 	
		     	  Quote: 	
		          Thanks for your expertise and help.  Jim said he has some more stuff he'll work

 on this weekend.  I'll wait on him and see what he comes up with before I order any parts. 	


    Sounds a like a plan. Thanks for the heads-up

    on those counters. That user programmable

    scale factor feature is slick.



 

   Bob . . .     	  Quote: 	
		  



href="http://www.matronics.com/Navigator?AeroElectric-List">http://www.matronics.com/Navigator?AeroElectric-List

href="http://forums.matronics.com/">http://forums.matronics.com

href="http://www.matronics.com/contribution">http://www.matronics.com/contribution



	


	


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