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Circuit needed

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jonlaury

Joined: 06 Nov 2006
Posts: 336

Posted: Fri Feb 02, 2007 10:43 am Post subject: Circuit needed

I have auxillary fuel  tanks that are pumped  to a header tank for use. I plan to use an OFF-ON-(ON) switch coupled with a  pressure switch (NC, and already in my parts bin) to activate a blinking LED  when there's no pressure and to activate the pump. When the pump pressurizes the  line and opens the p-switch, the LED goes to steady on. 

  

 Does one use a capacitor to get the LED to blink?  and is there a "null" between the  ON-(ON) positions?

  

 Obviously I need help on the circuit  design.

  

 Thanks for any help you can offer.

  

 John

   [quote][b]

nuckollsr(at)cox.net
Guest

Posted: Fri Feb 02, 2007 11:10 am Post subject: Circuit needed

At 10:17 AM 2/2/2007 -0800, you wrote:



 	  Quote: 	
		  I have auxillary fuel  tanks that are pumped to a header tank for use. I 

plan to use an OFF-ON-(ON) switch coupled with a pressure switch (NC, and 

already in my parts bin) to activate a blinking LED when there's no 

pressure and to activate the pump. When the pump pressurizes the line and 

opens the p-switch, the LED goes to steady on.



Does one use a capacitor to get the LED to blink?


	


    You can buy leds that flash . . . but it

    looks like you need the same led to light

    steady too. This will take some electronics.



    How does the pump develop and magnitude

    of pressure? Fuel transfer pumps generally

    operate into an open line to another tank

    with a very low order of pressure.



    You say you have a pressure switch. What

    pressure level causes it to change states?

 	  Quote: 	
		    and is there a "null" between the  ON-(ON) positions?


	


   No . . . not if it's a really good good switch . . .



 	  Quote: 	
		  

Obviously I need help on the circuit design.


	


    Need more 'input' . . .



        Bob . . .



        ----------------------------------------

        ( IF one aspires to be "world class",  )

        ( what ever you do must be exercised   )

        ( EVERY day . . .                      )

        (                  R. L. Nuckolls III  )

        ----------------------------------------

fvalarm(at)rapidnet.net
Guest

Posted: Fri Feb 02, 2007 11:31 am Post subject: Circuit needed

There are 12V LED's that come ready made to blink. Check  digikey.

  

 Bevan

 RV7A

 Egg H6 on order



   From:  owner-aeroelectric-list-server(at)matronics.com  [mailto:owner-aeroelectric-list-server(at)matronics.com] On Behalf Of John  Burnaby

Sent: Friday, February 02, 2007 10:18 AM

To:  aeroelectric-list(at)matronics.com

Subject: Circuit  needed

 

 I have auxillary fuel  tanks that are pumped  to a header tank for use. I plan to use an OFF-ON-(ON) switch coupled with a  pressure switch (NC, and already in my parts bin) to activate a blinking LED  when there's no pressure and to activate the pump. When the pump pressurizes the  line and opens the p-switch, the LED goes to steady on. 

  

 Does one use a capacitor to get the LED to blink?  and is there a "null" between the  ON-(ON) positions?

  

 Obviously I need help on the circuit  design.

  

 Thanks for any help you can offer.

  

 John

[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



[b]

jonlaury

Joined: 06 Nov 2006
Posts: 336

Posted: Fri Feb 02, 2007 10:12 pm Post subject: Circuit needed

 	  Quote: 	
		  Bob,The aux pump pushes fuel into an EFI return line, open to the header tank, via a check valve. The pressure switch that I have isa one psi oil pressure switch, hence NC. It seems to me that it's necessary to not have a null betweenOn and (On) so that pressure is maintained to keep the P-switch open as that open switch is what should keep the pump energized. So what does a "good, good" switch cost? or who makes one? If having the NC switch is causing grief, I could buy a NO switch. Upon first search, I was so happy with finding a one psi switch that I didn't think about it being an Oil Press. switch which would be normally closed to light the idiot light. The idiot light went on when I realized what I had done. At 10:17 AM 2/2/2007 -0800, you wrote:



 	  Quote: 	
		  I have auxillary fuel  tanks that are pumped to a header tank for use. I 

plan to use an OFF-ON-(ON) switch coupled with a pressure switch (NC, and 

already in my parts bin) to activate a blinking LED when there's no 

pressure and to activate the pump. When the pump pressurizes the line and 

opens the p-switch, the LED goes to steady on.



Does one use a capacitor to get the LED to blink?


	


    You can buy leds that flash . . . but it

    looks like you need the same led to light

    steady too. This will take some electronics.



    How does the pump develop and magnitude

    of pressure? Fuel transfer pumps generally

    operate into an open line to another tank

    with a very low order of pressure.The aux pump pushes fuel into an EFI return line, open to the header tank, via a check valve. The pressure switch that I have is 	
0 	  Quote: 	
		  The aux pump pushes fuel into an EFI return line, open to the header tank, via a check valve. The pressure switch that I have is 	
1 	  Quote: 	
		  The aux pump pushes fuel into an EFI return line, open to the header tank, via a check valve. The pressure switch that I have is 	
2

   [quote][b]

nuckollsr(at)cox.net
Guest

Posted: Sat Feb 03, 2007 9:20 am Post subject: Circuit needed

At 10:09 PM 2/2/2007 -0800, you wrote:

 	  Quote: 	
		  Bob,



The aux pump pushes fuel into an EFI return line, open to the header tank, 

via a check valve. The pressure switch that I have is



a one psi oil pressure switch, hence NC.


	


     Against what resistance to flow is the 1 psi expected to

     develop? Is the cracking pressure of the check valve

     greater than 1 psi?



 	  Quote: 	
		  It seems to me that it's necessary to not have a null between

On and (On) so that pressure is maintained to keep the P-switch open as 

that open switch is what should

keep the pump energized.


	


     Switches come in a host of characteristics that

     can define operating pressures +/- errors and

     drift, hysteresis, transfer times, etc.



 	  Quote: 	
		  So what does a "good, good" switch cost? or who makes one?

If having the NC switch is causing grief, I could buy a NO switch. Upon first

search, I was so happy with finding a one psi switch that I didn't think 

about it being an Oil Press.

switch which would be normally closed to light the idiot light. The idiot 

light went on when I realized

what I had done.


	


    Hmmmm . . . let me see if I really understand. You

    want a switch to operate when a pump develops a pressure

    against the back side of a check valve. Is it the

    purpose of this switch do de-energize the pump when

    the pressure drops below the desired switch point

    (i.e. is no longer moving fluid)?.



    Know that off-the-shelf oil pressure switches can have

    very wide tolerances to setpoint. Their purpose is

    to annunciate gross failures of oil pressure, not to

    warn of impending failure due to some reduction in

    oil pressure.



    There are some alternatives to oil pressure switches

    but I need to fully understand the task.



    Bob . . .

jonlaury

Joined: 06 Nov 2006
Posts: 336

Posted: Sun Feb 04, 2007 9:58 am Post subject: Circuit needed

I think the problem here is that I haven't  communicated what I want this circuit to do.

  

 When I power up the aux fuel pump switch  {Off-On-(On)}, I want an LED to flash, indicating power on and no fluid being  pumped. When I switch to (On) the pump should energize, pump fuel and pressurize  the line and P-switch upstream of the check valve. The P-switch should now take  over the power delivery to the pump, as long as it's closed/open under pressure,  and light a steady ON LED, indicating fluid being pumped. When the pump exhausts  the aux tank fuel, pressure should go to 0psi, P-switch opens/closes, pump  stops, LED flashes indicating no more fuel in line.

  

 Downstream, of the check valve, is the EFI return  line flow, with some marginal amount of pressure, that I think will add to and  be sufficient to actuate the P-switch.

  

 Sorry for the confusion.

 J

   [quote][b]

nuckollsr(at)cox.net
Guest

Posted: Sun Feb 04, 2007 12:25 pm Post subject: Circuit needed

At 08:59 AM 2/4/2007 -0800, you wrote:



 	  Quote: 	
		  I think the problem here is that I haven't communicated what I want this 

circuit to do.



When I power up the aux fuel pump switch {Off-On-(On)}, I want an LED to 

flash, indicating power on and no fluid being pumped. When I switch to 

(On) the pump should energize, pump fuel and pressurize the line and 

P-switch upstream of the check valve. The P-switch should now take over 

the power delivery to the pump, as long as it's closed/open under 

pressure, and light a steady ON LED, indicating fluid being pumped. When 

the pump exhausts the aux tank fuel, pressure should go to 0psi, P-switch 

opens/closes, pump stops, LED flashes indicating no more fuel in line.



Downstream, of the check valve, is the EFI return line flow, with some 

marginal amount of pressure, that I think will add to and be sufficient to 

actuate the P-switch.



Sorry for the confusion.


	


   Okay, I think I got it. Here's a cartoon of the concept.



http://www.aeroelectric.com/Pictures/Schematics/Fuel_Pump_Controller.pdf



   Moving switch from OFF to ON puts power on a 555 timer

   arranged to flash an LED but the pump remains un-powered.

   Holding the switch in the (ON) position applies power to

   pump and biases the flasher to "stick" in the steady-on

   state. If pressure comes up sufficiently to close the

   pressure switch, then the pump will continue to run, the

   light will stay steady after the switch is released. When

   pressure drops below set point on switch, power is removed

   from the pump and the flasher is allowed to resume its

   transitions between states.



   This begs for a microcontroller to allow use of either

   a normally open or normally closed switch. Further, while

   holding the switch in the (ON) position, the light should

   not be allowed to stop flashing UNLESS pressure comes up

   indicating that the system will stay in the fuel transfer

   mode after the switch is released.



   Keep in mind that this is a simplified diagram intended

   to speak to operating concept. It needs to be fleshed out

   for parts values and system interface details . . .



   Do I have it right?



   Bob . . .

        ----------------------------------------

        ( IF one aspires to be "world class",  )

        ( what ever you do must be exercised   )

        ( EVERY day . . .                      )

        (                  R. L. Nuckolls III  )

        ----------------------------------------

jonlaury

Joined: 06 Nov 2006
Posts: 336

Posted: Mon Feb 05, 2007 10:33 am Post subject: Circuit needed

[quote]EXACTLY! John    Okay, I think I got it. Here's a cartoon of the concept.



http://www.aeroelectric.com/Pictures/Schematics/Fuel_Pump_Controller.pdf



   Moving switch from OFF to ON puts power on a 555 timer

   arranged to flash an LED but the pump remains un-powered.

   Holding the switch in the (ON) position applies power to

   pump and biases the flasher to "stick" in the steady-on

   state. If pressure comes up sufficiently to close the

   pressure switch, then the pump will continue to run, the

   light will stay steady after the switch is released. When

   pressure drops below set point on switch, power is removed

   from the pump and the flasher is allowed to resume its

   transitions between states.



   This begs for a microcontroller to allow use of either

   a normally open or normally closed switch. Further, while

   holding the switch in the (ON) position, the light should

   not be allowed to stop flashing UNLESS pressure comes up

   indicating that the system will stay in the fuel transfer

   mode after the switch is released.



   Keep in mind that this is a simplified diagram intended

   to speak to operating concept. It needs to be fleshed out

   for parts values and system interface details . . .



   Do I have it right?[b]

john(at)ballofshame.com
Guest

Posted: Mon Feb 05, 2007 10:51 am Post subject: Circuit needed

re: computer control.  Interesting you should mention that.  I've been

fiddling around with the BASIC Stamp processors lately.



http://www.hobbyengineering.com/SectionBS.html#IX1024



These things ROCK and are very simple to program.  They're perfectly

suited to doing things like simple logic, monitoring, flashing LED's, etc

etc.



They run on 9V so you need a regulator or transformer of some sort.  You

will also have to build in some simple protection from spikes and maybe

low voltage.  I've been collecting a list of tons of different

applications for these things.  Everything from solid state interlocks to

annunciators.



Neat stuff and not too expensive.



-John

www.ballofshame.com



 	  Quote: 	
		   EXACTLY!John   Okay, I think I got it. Here's a cartoon of the concept.



 http://www.aeroelectric.com/Pictures/Schematics/Fuel_Pump_Controller.pdf



    Moving switch from OFF to ON puts power on a 555 timer

    arranged to flash an LED but the pump remains un-powered.

    Holding the switch in the (ON) position applies power to

    pump and biases the flasher to "stick" in the steady-on

    state. If pressure comes up sufficiently to close the

    pressure switch, then the pump will continue to run, the

    light will stay steady after the switch is released. When

    pressure drops below set point on switch, power is removed

    from the pump and the flasher is allowed to resume its

    transitions between states.



    This begs for a microcontroller to allow use of either

    a normally open or normally closed switch. Further, while

    holding the switch in the (ON) position, the light should

    not be allowed to stop flashing UNLESS pressure comes up

    indicating that the system will stay in the fuel transfer

    mode after the switch is released.



    Keep in mind that this is a simplified diagram intended

    to speak to operating concept. It needs to be fleshed out

    for parts values and system interface details . . .



    Do I have it right?

nuckollsr(at)cox.net
Guest

Posted: Mon Feb 05, 2007 6:35 pm Post subject: Circuit needed

At 10:51 AM 2/5/2007 -0800, you wrote:



 	  Quote: 	
		  



re: computer control.  Interesting you should mention that.  I've been

fiddling around with the BASIC Stamp processors lately.



http://www.hobbyengineering.com/SectionBS.html#IX1024



These things ROCK and are very simple to program.  They're perfectly

suited to doing things like simple logic, monitoring, flashing LED's, etc

etc.



They run on 9V so you need a regulator or transformer of some sort.  You

will also have to build in some simple protection from spikes and maybe

low voltage.  I've been collecting a list of tons of different

applications for these things.  Everything from solid state interlocks to

annunciators.



Neat stuff and not too expensive.


	


   That works. Right now we're working with one of the Stamp's little

   brothers, he PIC12F683. My software guy is getting really talented

   with this chip (costs just over $1 in hundreds) and has a lot

   of features for the cost. Programmers are dirt-cheap too.

   Of the ones we've tried so far, the PICkit-II is our favorite



http://www.digikey.com/scripts/DkSearch/dksus.dll?Detail?Ref 72536&Row=688347&Site=US



   It comes with an editor-assembler-debugger package for under

   $40. This chip is the core of our AEC9011 and about a dozen

   other products in the development pipe.



        Bob . . .



        ----------------------------------------

        ( IF one aspires to be "world class",  )

        ( what ever you do must be exercised   )

        ( EVERY day . . .                      )

        (                  R. L. Nuckolls III  )

        ----------------------------------------

nuckollsr(at)cox.net
Guest

Posted: Tue Feb 06, 2007 7:07 am Post subject: Circuit needed

At 10:18 AM 2/5/2007 -0800, you wrote:

 	  Quote: 	
		  EXACTLY!



John


	


  Okay, I can pop a uC chip with the code to nicely

  implement the idealized control scenario. The weakest

  link in the chain is pressure switch selection.

  Have you pressure tested the switch you have in hand?

  We can make a NC switch work in the software but

  it would be much better if you had an NO device.

  It would be even better if the switch were adjustable.

  Check out pages 4-5 of



http://content.honeywell.com/sensing/hss/hobbscorp/pdf/cat_pav.pdf



   Bob . . .

        ----------------------------------------

        ( IF one aspires to be "world class",  )

        ( what ever you do must be exercised   )

        ( EVERY day . . .                      )

        (                  R. L. Nuckolls III  )

        ----------------------------------------

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