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Van's Ammeter

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rhdudley1(at)bellsouth.ne
Guest

Posted: Wed Feb 28, 2007 5:31 pm Post subject: Van's Ammeter

Listers,

I have a Van's - 0 + ammeter. It is very sensitive to rapidly changing 

loads, especially to the strobe load. The needle is in constant 

vibration while the strobes are on and/or the landing/taxi light wig-wag 

is wig-wagging .  Is there a reasonable means (preferably connected 

externally)  for increasing its response time. Its external connections 

are gnd, power, and  two terminals to the shunt.



Thanks in advance for suggestions.



Richard Dudley

RV-6A flying

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nuckollsr(at)cox.net
Guest

Posted: Wed Feb 28, 2007 6:15 pm Post subject: Van's Ammeter

At 08:30 PM 2/28/2007 -0500, you wrote:



 	  Quote: 	
		  

<rhdudley1(at)bellsouth.net>



Listers,

I have a Van's - 0 + ammeter. It is very sensitive to rapidly changing 

loads, especially to the strobe load. The needle is in constant vibration 

while the strobes are on and/or the landing/taxi light wig-wag is 

wig-wagging .  Is there a reasonable means (preferably connected 

externally)  for increasing its response time. Its external connections 

are gnd, power, and  two terminals to the shunt.



Thanks in advance for suggestions.



Richard Dudley

RV-6A flying


	


   This instrument is a very low-impedance device (40mv full

   scale as I recall) in terms of adding damping. The really

   slick way to damp these devices is to put a drop of hi-viscosity

   silicone oil in the pivot bearings. We experimented with this

   at Cessna about 1965 . . . it worked really well. I think

   we had Stewart-Warner do that mod on future units but I

   don't recall now. There's a 50,000 cts "differential lock"

   oil that's popular with the electric race car crowd that costs

   about $5.00 for a 1 oz bottle. One drop on each bearing

   would damp it very nicely.



   The problem with doing the job electrically is that the

   source impedance for the driving signal is VERY low . . .

   like a few milliohms. It takes a whopping capacitor to

   add much time-constant at this low level. Try putting say

   a 10 ohm resistor in series with one of the shunt leads

   and the parallel the instrument with the biggest capacitor

   you can find. I've got some 330uf/6v tantalums you could

   try. About three of those in parallel would get 1000uF.

   This MIGHT be useful to try.



   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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rhdudley1(at)bellsouth.ne
Guest

Posted: Thu Mar 01, 2007 6:45 am Post subject: Van's Ammeter

Bob,

Thanks for the reply.

I would prefer trying the external experiment before considering opening 

the meter.

So, I'd like to take you up on your offer of the loan your capacitors to 

do the experiment. If it works, I'll replace your caps.

Earlier, I tried to surpress RF which pinned the meter when I 

transmitted. A ferrite clamp on  one lead did reduce the reaction.

My address is

RH Dudley

8425 Littleleaf Ct.

Orlando, FL 32835

Thanks.

Regards,

Richard Dudley

Robert L. Nuckolls, III wrote:

 	  Quote: 	

 <nuckollsr(at)cox.net>

 At 08:30 PM 2/28/2007 -0500, you wrote:

> 

> <rhdudley1(at)bellsouth.net>

>

> Listers,

> I have a Van's - 0 + ammeter. It is very sensitive to rapidly 

> changing loads, especially to the strobe load. The needle is in 

> constant vibration while the strobes are on and/or the landing/taxi 

> light wig-wag is wig-wagging .  Is there a reasonable means 

> (preferably connected externally)  for increasing its response time. 

> Its external connections are gnd, power, and  two terminals to the 

> shunt.

>

> Thanks in advance for suggestions.

>

> Richard Dudley

> RV-6A flying

   This instrument is a very low-impedance device (40mv full

   scale as I recall) in terms of adding damping. The really

   slick way to damp these devices is to put a drop of hi-viscosity

   silicone oil in the pivot bearings. We experimented with this

   at Cessna about 1965 . . . it worked really well. I think

   we had Stewart-Warner do that mod on future units but I

   don't recall now. There's a 50,000 cts "differential lock"

   oil that's popular with the electric race car crowd that costs

   about $5.00 for a 1 oz bottle. One drop on each bearing

   would damp it very nicely.

   The problem with doing the job electrically is that the

   source impedance for the driving signal is VERY low . . .

   like a few milliohms. It takes a whopping capacitor to

   add much time-constant at this low level. Try putting say

   a 10 ohm resistor in series with one of the shunt leads

   and the parallel the instrument with the biggest capacitor

   you can find. I've got some 330uf/6v tantalums you could

   try. About three of those in parallel would get 1000uF.

   This MIGHT be useful to try.

   Bob . . .

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

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

        ( what ever you do must be exercised   )

        ( EVERY day . . .                      )

        (                  R. L. Nuckolls III  )

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

- The Matronics AeroElectric-List Email Forum -

Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:

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nuckollsr(at)cox.net
Guest

Posted: Thu Mar 01, 2007 8:58 am Post subject: Van's Ammeter

At 09:44 AM 3/1/2007 -0500, you wrote:



 	  Quote: 	
		  

<rhdudley1(at)bellsouth.net>



Bob,

Thanks for the reply.

I would prefer trying the external experiment before considering opening 

the meter.

So, I'd like to take you up on your offer of the loan your capacitors to 

do the experiment. If it works, I'll replace your caps.

Earlier, I tried to surpress RF which pinned the meter when I transmitted. 

A ferrite clamp on  one lead did reduce the reaction.


	


    ????? an RF sensitive ammeter ????



    This doesn't sound like the instrument I looked at

    several years ago that came from Vans. Is this a powered

    device? More than two wires that only come from a shunt?

 	  Quote: 	
		  My address is

RH Dudley

8425 Littleleaf Ct.

Orlando, FL 32835

Thanks.



Regards,

Richard Dudley

- The Matronics AeroElectric-List Email Forum -

Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:

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rhdudley1(at)bellsouth.ne
Guest

Posted: Thu Mar 01, 2007 9:13 am Post subject: Van's Ammeter

Bob,

Yes, as I mentioned in my first e-mail, there are four connections, two 

in addition to the shunt for power and ground.



Robert L. Nuckolls, III wrote:



 	  Quote: 	
		   

 <nuckollsr(at)cox.net>



 At 09:44 AM 3/1/2007 -0500, you wrote:



> 

> <rhdudley1(at)bellsouth.net>

>

> Bob,

> Thanks for the reply.

> I would prefer trying the external experiment before considering 

> opening the meter.

> So, I'd like to take you up on your offer of the loan your capacitors 

> to do the experiment. If it works, I'll replace your caps.

> Earlier, I tried to surpress RF which pinned the meter when I 

> transmitted. A ferrite clamp on  one lead did reduce the reaction.

    ????? an RF sensitive ammeter ????



    This doesn't sound like the instrument I looked at

    several years ago that came from Vans. Is this a powered

    device? More than two wires that only come from a shunt?

> My address is

> RH Dudley

> 8425 Littleleaf Ct.

> Orlando, FL 32835

> Thanks.

>

> Regards,

> Richard Dudley

- The Matronics AeroElectric-List Email Forum -

Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:

http://www.matronics.com/Navigator?AeroElectric-List

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