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IVO Prop Current Limiter/Electronic Circuit Breaker

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nuckolls.bob(at)aeroelect
Guest

Posted: Thu Apr 29, 2010 7:34 am Post subject: IVO Prop Current Limiter/Electronic Circuit Breaker

It took a bit more 'praying' than I anticipated

and I'm only 99.6% sure that my confidence in

having met design goals have been met. But I'll

invite other 'electron herders' on the List

to review the following and see if I've stubbed

my toe anywhere:



See:



http://aeroelectric.com/Pictures/Schematics/IVO-Prop_Pitch_Controller.pdf



Design goals:



Provide absolute current limit on the order of 9A:



   Q114 is a power FET that saturates with bias

   through R104, R105 and D109 when power is applied

   through "M" connections that sense motor power.



   Voltage drop across R117/R118 is monitored through

   R116 causing Q115 to turn on when drop across the

   R117/118 exceeds Vbe of Q115. This is approx .6

   volts. When Q115 turns on, it starves Q114 of gate

   drive and causes it to become a constant current

   generator with calibration set by the combination

   of R117/R118.



   Any time the constant current loop is active,

   LED D109 will be illuminated. D109 will flash

   each time the prop pitch motor is energized

   and the system becomes an active inrush current

   limiter.



Limit the duration of the current limit mode to

100-200 mS whereupon the system goes open circuit

and removes power from the motor:



   At any time the current limiter is active,

   Q115 collector current through R105 will turn

   on Q103 causing the collector to pull up to

   the supply rail. This causes C112 to charge

   through R106 until zener D110 conducts at about

   8V. This event will occur approximately 120 mS

   after onset of current limit.



   When D110 conducts, it pulls the base of Q115

   more positive causing the Q115/Q103 pair to

   "latch up" not unlike an SCR. When the latching

   event occurs, the collector of Q115 pulls to

   a few millivolts above ground depriving Q114

   of all gate drive.



Normal operation:



   D109 will flash each time the motor control switch

   is closed due to motor inrush current being

   electronically limited. D109 will also flash a

   bit longer (about 120 mS) when the prop pitch motor

   reaches the mechanical stop and the current limit is

   invoked.



   As long as the prop pitch motor is powered

   D108 will be illuminated. When the prop

   pitch system reaches a mechanical limit and

   the control switch is NOT relaxed,  D019 flashes

   for about 120 mS and D108 goes dark.



   Releasing the motor control switch removes

   power from the latching loop and discharges

   C112 through R119, R104, BC junction Q103,

   and R106.



   The system spends so little time in I-limit

   mode that Q114 does not require a heat-sink.

   D109 and D108 staying on together indicates

   a malfunction and the motor control switch

   needs to be released within a second or so

   to avoid over-heat damage to Q114.



   Don't anyone run out and build this yet. Let's

   thrash the bushes a bit for rats.



   Bob . . .

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dennis.glaeser(at)hp.com
Guest

Posted: Fri Apr 30, 2010 8:43 am Post subject: IVO Prop Current Limiter/Electronic Circuit Breaker

Bob,



The reed switch circuit is already in place and operational, so my initial goal has been achieved! 



I already have the parts for the first design - only half assembled at the moment (having to work for a living gets in the way of the 'important stuff' 



The latest design literally dummy-proofs the operation of the IVO, and will undoubtedly increase the MTBF of the motor and gearbox by limiting the motor electrically rather than mechanically jamming the gears!



I can follow your description on how it works, but my knowledge falls short of being able to analyze and comment.  When you declare the updated circuit complete, I'll build it (already have most of the components  and let you know how it works!



It was me who was doing the 'praying' for a solution!  You did the 'perspiration' part - per Thomas Edison.



Thanks,



	Dennis



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

From: Robert L. Nuckolls, III 



It took a bit more 'praying' than I anticipated

and I'm only 99.6% sure that my confidence in

having met design goals have been met. But I'll

invite other 'electron herders' on the List

to review the following and see if I've stubbed

my toe anywhere:



See:



http://aeroelectric.com/Pictures/Schematics/IVO-Prop_Pitch_Controller.pdf

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

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N20DG

Joined: 02 Jan 2008
Posts: 61
Location: lancaster, texas

Posted: Fri Apr 30, 2010 4:31 pm Post subject: IVO Prop Current Limiter/Electronic Circuit Breaker

Dennis

 Do you have a circuit diagram/photos of your installation that you can  share??

 Thanks

 Dick

  

  In a message dated 4/30/2010 11:44:48 A.M. Central Daylight Time,  dennis.glaeser(at)hp.com writes:

  	  Quote: 	
		  -->    AeroElectric-List message posted by: "Glaeser, Dennis"    <dennis.glaeser(at)hp.com>



Bob,



The reed switch circuit is    already in place and operational, so my initial goal has been achieved!    



I already have the parts for the first design - only half assembled at    the moment (having to work for a living gets in the way of the 'important    stuff' 



The latest design literally dummy-proofs the operation of    the IVO, and will undoubtedly increase the MTBF of the motor and gearbox by    limiting the motor electrically rather than mechanically jamming the    gears!



I can follow your description on how it works, but my knowledge    falls short of being able to analyze and comment.  When you declare the    updated circuit complete, I'll build it (already have most of the components     and let you know how it works!



It was me who was doing the    'praying' for a solution!  You did the 'perspiration' part - per Thomas    Edison.



Thanks,



       Dennis



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

From: Robert L. Nuckolls,    III 



It took a bit more 'praying' than I anticipated

and I'm only    99.6% sure that my confidence in

having met design goals have been met. But    I'll

invite other 'electron herders' on the List

to review the following    and see if I've stubbed

my toe    anywhere:



See:



http://aeroelectric.com/Pictures/Schematics/IVO-Prop_Pitch_Controller.pdf

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

========================= Use   utilities  Day  ================================================               - MATRONICS WEB FORUMS  ================================================             - List Contribution Web Site  sp;                             ===================================================



	


  [quote][b]

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user9253

Joined: 28 Mar 2008
Posts: 1927
Location: Riley TWP Michigan

Posted: Mon May 03, 2010 4:13 am Post subject: Re: IVO Prop Current Limiter/Electronic Circuit Breaker

 	  Quote: 	
		  Dennis

Do you have a circuit diagram/photos of your installation that you can  

share??

Thanks

Dick 	


Dick,

Did you see this picture that Dennis posted?

http://forums.matronics.com/viewtopic.php?t=70557&sid=1bdd10db5d3c9ab625b4465b86c3de08

No modification is required to the existing prop motor circuit.  Just find some slack in a wire going to the motor (hot or ground doesn't matter) and wrap 3 turns around a reed switch.  Then connect the reed switch in series with a power source and indicator LED.  The reed switch is made of glass and will break easily.  It should not be stressed by the lead wires or while wrapping with turns of wire.  Also, a heat-sink should be used if soldered because the switch will be damaged by heat.

Joe

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_________________
Joe Gores

N20DG

Joined: 02 Jan 2008
Posts: 61
Location: lancaster, texas

Posted: Mon May 03, 2010 8:31 am Post subject: IVO Prop Current Limiter/Electronic Circuit Breaker

Joe

 Dennis sent me some additional photos and a wiring diagram off line showing  what I wanted to know.

 I will be modifying the wiring some when I get to that project

 Thanks

 Dick

  

  In a message dated 5/3/2010 7:26:59 A.M. Central Daylight Time,  fran4sew(at)banyanol.com writes:

  	  Quote: 	
		  -->    AeroElectric-List message posted by: "user9253"    <fran4sew(at)banyanol.com>

 	  Quote: 	
		   Dennis

 Do you have a    circuit diagram/photos of your installation that you can  

    share??

 Thanks

 Dick


	


Dick,

Did you see this picture    that Dennis    posted?

http://forums.matronics.com/viewtopic.php?t=70557&sid=1bdd10db5d3c9ab625b4465b86c3de08

No    modification is required to the existing prop motor circuit.  Just find    some slack in a wire going to the motor (hot or ground doesn't matter) and    wrap 3 turns around a reed switch.  Then connect the reed switch in    series with a power source and indicator LED.  The reed switch is made of    glass and will break easily.  It should not be stressed by the lead wires    or while wrapping with turns of wire.  Also, a heat-sink should be used    if soldered because the switch will be damaged by    heat.

Joe



--------

Joe Gores





Read this topic    online    here:



http://forums.matronics.com/viewtopic.php?p=296570#296570===============================================

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  [quote][b]

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