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Insrument Lighting

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jlinga(at)mchsi.com
Guest

Posted: Wed Jul 05, 2006 6:54 pm Post subject: Insrument Lighting

Hey Guys,

     Thanks to Eric, Ken ,  and Charlie for your suggestions.  However, I don't have any idea on how to  build a PWM or variable duty cycle circuit.  Do you guys have any  schematics or more info?  Thanks Charlie for including the  link.

     I don't plan on  disconnecting the instrument or covering it up.  I have the g-meter lit for  aesthetics and symmetry.  I paid extra to have it lit, so I plan on using  it. 

     I called the  manufacturer of the g-meter.  The reason the instrument is so bright is  that it actually has three bulbs drawing a total of 0.56.  The company  verified my amp draw correct for a 12 v unit.  So at least I know I have  the right bulbs.  I still need to dim it down a bit to make the brightness  similar to the rest of the instruments.  Bob K., do you have any  ideas?

  

 Thank you,

 Jerry

  

 --> AeroElectric-List message posted by:  Ken <klehman(at)albedo.net ([email]klehman(at)albedo.net?subject=Re:%20Instrument%20lighting&replyto=44A5201A.9050100(at)albedo.net[/email])>



Hi Jerry

I'd say you did it all correctly but you are just  surprised at how much 

the 2.5 watts heats up a resistor. A 5 watt bulb is  about what 

incandescent children's night lights are and does seem ridiculous  for an 

instrument so I agree that is is the wrong bulb. I would leave it as  is 

with your resistor. Second choice would be change the bulb to one that  

is really 12 volts. Third choice is a variable duty cycle circuit that  

pulses short 12 volt pulses to the lamp so that it averages the same  

power as running it on 5 volts. That avoids heating up a resistor and  

dumping the 2.5 watts but I doubt it is worth the trouble. Fourth choice  

is kind of silly but if you had another similar instrument you could  

wire them is series...

Ken



Jerry & Ledy Esquenazi  wrote:



 	  Quote: 	
		   Hey Guys,

     I have a simple  problem that most likely has a simple solution.  

 The solution,  however, eludes me.  I have an internally lit g-meter on 

 my  instrument panel (Don't ask me why ).  The g-meter's lighting is  

 internal to the instrument, i.e. it's not a lighting tray that is  

 screwed to the top.  The instrument would have to be opened up to  get 

 to the lamp.

  

     I  purchased the g-meter from Chief a while back ago, and when I 

 received  it, I realized it was a 5v unit.  Chief didn't have any other 

  lighting option listed or available.  I thought about dropping the 

  voltage with a resistor.  Before doing this I called the manufacturer  

 Wultrad (aka Falcon Gauge).  They said they had a 12v unit in  stock 

 that they could swap for mine.  I thought... "great problem  solved."  

 They shipped me one back with a 12v label over the  original label.  In 

 testing my instrument panel lighting, I  discovered that the g-meter is 

 considerably brighter than the other  instruments to the point it would 

 be annoying at night.  The  interesting thing is the light is nice and 

 white and very uniform  though out the face of the instrument.  Anyway, 

 I thought... "gee  I'm back to putting in a resistor to dim the light!"

   

     "OK, no problem.  I'll figure out what  size resistor I need and 

 move on," I thought.  The problem is the  resistance of any 

 incandescent lamp changes whether it hot or  cold.  The lamp is drawing 

 0.56 A at 12.0 v.  Seem's like a  lot to me.  From that I deduced the 

 lamp's resistance at 21.3  ohm.  The problem is that when I figure out 

 what size resistor I  need to get say a 7 or 8 v voltage drop across 

 the lamp and add that  resistor to the circuit, the current changes and 

 so does the resistance  of the lamp.  So how does one figure this stuff 

 out?  I  decided to purchase a potentiometer and install it in my 

 circuit,  adjust it 'till I got the brightness I wanted and then 

 measure the  resistance of the pot.  In doing this I began to smell 

 smoke, the  little pot was beginning to glow red as I dimmed down the 

 light in the  instrument.  I went back and purchased a heavier pot.  

 This  did the trick.  I decided a 20 ohm resistor in series would be 

  perfect.  I purchased a 22 ohm, 2 W resistor, temporarily installed  

 it, and the light was perfect.  The problem was I was still  smelling 

 that familiar acrid smell.  I had a 7.4 v drop across the  resistor and 

 a .34 A current giving me 2.5 W to dissipate.  I  later tried two 10 

 ohm, 2 W resistors in series.  Still, they got  too hot.  I purchased a 

 ceramic 22 ohm, 5 W resistor and it still  got too hot to touch.  The 

 small battery I was using for testing  was putting out 12.2 v under the 

 load.  I had a 7.4 v drop across  the resistor, So I deduced I must be 

 getting a 4.8 v drop across the  lamp.  The light was just right.  I 

 wonder if I still have a  5v lamp inside the instrument!  I measured 

 0.34 A in the  circuit.  The 5 W resistor ought to be handling the 2.5 

 W I need  to dissipate just fine.  Something is wrong.  Do any of you 

  smart guys know what I'm doing wrong?

  

 Jerry

  "Smelling smoke in Georgia

FLYaDIVE(at)aol.com
Guest

Posted: Thu Jul 06, 2006 4:11 am Post subject: Insrument Lighting

Jerry:



I hate the place, but take a ride to Radio Shack.  Get an LM-317 voltage 

regulator, right on the packaging there is a schematic of how to build and what 

parts are required for a very effective voltage regulator.



The hardest and most frustrating part is dealing with the total mental 

midgets behind the counter.  They don't know the difference between a diode, 

resistor or a capacitor.  And god forbid, they get off their ass and look for 

something or say anything more than, "If you don't see it we don't have it."  Or, 

"Want to buy a cell phone?"



Barry

"Chop'd Liver"

jschroeder(at)perigee.net
Guest

Posted: Thu Jul 06, 2006 4:49 am Post subject: Insrument Lighting

Amen, brother.



It is a shame that they have migrated so far off the hobbyist pathways. In  

fact, it is hard to find any electronics store fronts these days. There  

are none in the Charlotte area anymore.



Cheers,



John



DO NOT ARCHIVE



On Thu, 6 Jul 2006 08:04:50 EDT, <FLYaDIVE(at)aol.com> wrote:



 	  Quote: 	
		   The hardest and most frustrating part is dealing with the total mental

 midgets behind the counter.  They don't know the difference between a  

 diode,

 resistor or a capacitor.  And god forbid, they get off their ass and  

 look for

 something or say anything more than, "If you don't see it we don't have  

 it."  Or,

 "Want to buy a cell phone?"


	


--

kayce33(at)earthlink.net
Guest

Posted: Thu Jul 06, 2006 6:54 am Post subject: Insrument Lighting

I live on the wrong coast, but I've been to FRYS south of Portland, seems as 

if they have something for everyone.

Harold

deej(at)deej.net
Guest

Posted: Thu Jul 06, 2006 8:25 am Post subject: Insrument Lighting

On Thu, 6 Jul 2006, Harold wrote:



 	  Quote: 	
		   



 I live on the wrong coast, but I've been to FRYS south of Portland, seems as 

 if they have something for everyone.

 Harold


	


 	If I remember correctly, the ILS 18 approach to Lebanon NH (KLEB) 

is HAMMM, BURGR, FRYYS...  *grin*



-Dj



do not archive

Jerry Cochran

Joined: 10 Jan 2006
Posts: 111
Location: Wilsonville, OR

Posted: Fri Jul 07, 2006 6:20 am Post subject: Insrument Lighting

I live 10 minutes from Fry's but when needing  electronic stuff  and want advice from someone who actually knows about it, I go to Norvac. http://www.norvac.net/

 They have everything including stuff like shielded wire that gets you a  blank stare at Fry's... 

  

 My .10, do not archive.

  

 Jerry Cochran

 Wilsonville, OR

  	  Quote: 	
		  From:    "Harold" <kayce33(at)earthlink.net>

Subject: Re: AeroElectric-List: RE:    Insrument Lighting



--> AeroElectric-List message posted by: "Harold"    <kayce33(at)earthlink.net>



I live on the wrong coast, but I've been    to FRYS south of Portland, seems as 

if they have something for    everyone.

Harold

plaurence

Joined: 22 May 2006
Posts: 15

Posted: Fri Jul 07, 2006 6:04 pm Post subject: Insrument Lighting

Jerry,   

   

If you have a combination of incandescent and LEDs you can control the brightness with a unit made by A and T labs. You can daisy-chain the modules and control the overall brightness with a master. Obviously it will also level out different intensities of incandescenst. You can find them at http://www.a-and-t-labs.com/  

   

   

Peter  

         

  

From: owner-aeroelectric-list-server(at)matronics.com [mailto:owner-aeroelectric-list-server(at)matronics.com] On Behalf Of Jerry & Ledy Esquenazi

 Sent: Wednesday, July 05, 2006 10:52 PM

 To: AeroElectric-List(at)matronics.com

 Subject: RE: Insrument Lighting  

  

     

Hey Guys,  

    

    Thanks to Eric, Ken , and Charlie for your suggestions.  However, I don't have any idea on how to build a PWM or variable duty cycle circuit.  Do you guys have any schematics or more info?  Thanks Charlie for including the link.  

    

    I don't plan on disconnecting the instrument or covering it up.  I have the g-meter lit for aesthetics and symmetry.  I paid extra to have it lit, so I plan on using it.   

    

    I called the manufacturer of the g-meter.  The reason the instrument is so bright is that it actually has three bulbs drawing a total of 0.56.  The company verified my amp draw correct for a 12 v unit.  So at least I know I have the right bulbs.  I still need to dim it down a bit to make the brightness similar to the rest of the instruments.  Bob K., do you have any ideas?  

    

   

    

Thank you,  

    

Jerry

_________________
Peter Laurence
RV9A Fuse

harley(at)AgelessWings.co
Guest

Posted: Sat Jul 08, 2006 3:50 am Post subject: Insrument Lighting

Morning, Peter...

 

 >>www.a-and-t-labs.com/<<

 

 Great website! Not only do they sell the kits, or just the PC board (the parts list states that they are all available at Digi-Key), but they have the complete circuit description, block diagrams, schematic diagrams and all the artwork for a PC board on the site for those who want to home brew it! 

 

 Note that the dimmer also has a photocell option to turn on the lights when the cockpit gets too dark.  Looks like they thought of everything...good link, thanks, Peter. 

   

 Harley Dixon

 

 

 Peter Laurence wrote:  	  Quote: 	
		           v\:* {behavior:url(#default#VML);} o\:* {behavior:url(#default#VML);} w\:* {behavior:url(#default#VML);} .shape {behavior:url(#default#VML);}  <![endif]-->          <![endif]-->       <![endif]-->      

Jerry,    

    

If you have a combination of incandescent and LEDs you can control the brightness with a unit made by A and T labs. You can daisy-chain the modules and control the overall brightness with a master. Obviously it will also level out different intensities of incandescenst. You can find them at http://www.a-and-t-labs.com/   

    

    

Peter   

          

   

From: owner-aeroelectric-list-server(at)matronics.com (owner-aeroelectric-list-server(at)matronics.com) [mailto:owner-aeroelectric-list-server(at)matronics.com (owner-aeroelectric-list-server(at)matronics.com)] On Behalf Of Jerry & Ledy Esquenazi

   Sent: Wednesday, July 05, 2006 10:52 PM

   To: AeroElectric-List(at)matronics.com (AeroElectric-List(at)matronics.com)

   Subject: RE: Insrument Lighting   

   

       

Hey Guys,   

      

    Thanks to Eric, Ken , and Charlie for your suggestions.  However, I don't have any idea on how to build a PWM or variable duty cycle circuit.  Do you guys have any schematics or more info?  Thanks Charlie for including the link.   

      

    I don't plan on disconnecting the instrument or covering it up.  I have the g-meter lit for aesthetics and symmetry.  I paid extra to have it lit, so I plan on using it.    

      

    I called the manufacturer of the g-meter.  The reason the instrument is so bright is that it actually has three bulbs drawing a total of 0.56.  The company verified my amp draw correct for a 12 v unit.  So at least I know I have the right bulbs.  I still need to dim it down a bit to make the brightness similar to the rest of the instruments.  Bob K., do you have any ideas?   

      

    

      

Thank you,   

      

Jerry

FLYaDIVE(at)aol.com
Guest

Posted: Sat Jul 08, 2006 5:14 am Post subject: Insrument Lighting

In a message dated 7/8/06 7:52:41 AM Eastern Daylight Time, 

harley(at)AgelessWings.com writes:



 	  Quote: 	
		   Note that the dimmer also has a photocell option to turn on the lights 

  when the cockpit gets too dark.  Looks like they thought of 

  everything...good link, thanks, Peter.

   

  Harley Dixon

  

=======================
	


Hey Guys ...



Are you really willing to spend $75 for a simple dimmer?  As I stated before, 

as much as I dislike Radio Shack you can build this dimmer for $15 to $20 

with all parts and instructions available from the $hit Shack.



LQQK for the LM-317



Barry

"Chop'd Liver"

harley(at)AgelessWings.co
Guest

Posted: Sat Jul 08, 2006 5:41 am Post subject: Insrument Lighting

FLYaDIVE(at)aol.com (FLYaDIVE(at)aol.com) wrote:  	  Quote: 	
		      	  Quote: 	
		  --> AeroElectric-List message posted by: FLYaDIVE(at)aol.com (FLYaDIVE(at)aol.com)



In a message dated 7/8/06 7:52:41 AM Eastern Daylight Time, 

harley(at)AgelessWings.com (harley(at)AgelessWings.com) writes:



        	  Quote: 	
		  Note that the dimmer also has a photocell option to turn on the lights 

 when the cockpit gets too dark.  Looks like they thought of 

 everything...good link, thanks, Peter.

  

 Harley Dixon

 

    	
   =======================

Hey Guys ...



Are you really willing to spend $75 for a simple dimmer?  As I stated before, 

as much as I dislike Radio Shack you can build this dimmer for $15 to $20 

with all parts and instructions available from the $hit Shack.



LQQK for the LM-317



Barry

"Chop'd Liver"

  	
 	
 

 Morning, Barry (or, are we supposed to call you Chop'd Liver? <G>)...

 

 >>spend $75 for a simple dimmer?<<

 

 That's why I supported Peter's choice of that link...the web site doesn't limit one to purchasing their unit.  It has a complete schematic, block diagram, parts list, etc..., and mentions that all the parts can be purchased from Digi-key...but, of course, one can buy them wherever you'd like, Radio Shack not excluded. Mouser being my first choice.

 

 The PDF for the description and schematic for it is here:

 www.a-and-t-labs.com/K11_Dimmer/Dimmer_with_figs.pdf

 

 Includes instructions for construction on a perf board, or a pc board which you can make yourself from their artwork or buy from them and add the parts, installation instructions, etc. 

 

 Their feature list in the above document says:

 ·  Multiple outputs with tracking capability

 ·  Day time full brightness over-ride capability

 ·  Reliability

 ·  Current limiting/short circuit protection

 ·  Thermal protection

 ·  Low drop-out voltage (ability to adjust the dimmer bus up as close to the battery

    voltage as possible)

 ·  Photocell light sensor automatic control capability

 ·  Low cost

 

 A little more than the Radio shack dimmer.

 

 It's beginning to sound like I'm affiliated with A&T Labs in some way...I assure you, I am not.  I just appreciate a company that offers the option to build or buy...and makes nothing off of it if you build.  

 

 After all, that's why I have a Long EZ <G>. 

 

 Harley

FLYaDIVE(at)aol.com
Guest

Posted: Sat Jul 08, 2006 8:26 am Post subject: Insrument Lighting

In a message dated 7/8/06 9:44:29 AM Eastern Daylight Time, 

harley(at)AgelessWings.com writes:



 	  Quote: 	
		   Morning, Barry (or, are we supposed to call you Chop'd Liver? <G>)...

  

Harley:
	




You can call me Barry 

You can call me Chop'd Liver 

You can call me Gimp

But don't call me Johnson!



Chop'd Liver and Gimp are my Callsigns.  Flight callsign is NUGGET

If I'm working ATC then it is NUGGET 01



Barry

"Chop'd Liver"

Eric M. Jones

Joined: 10 Jan 2006
Posts: 565
Location: Massachusetts

Posted: Sun Jul 09, 2006 4:47 pm Post subject: Re: Insrument Lighting

An instrument with internal tungsten lamps should be easy to convert to LEDs. This has many benefits, and the LEDs are available in exact replacement sizes. (Ledtronics and others places).



I  sell the "Extremely General Purpose Adjustable Voltage Regulator" that is used for dimming purposes and is smaller and lighter than anything you could build from a kit. For $99 for four of them, it's hard to beat the price. too. Share them with a fellow builder.

EGPAVR.pdf

Description:

Download

Filename:

EGPAVR.pdf

Filesize:

172.32 KB

Downloaded:

513 Time(s)

_________________
Eric M. Jones
www.PerihelionDesign.com
113 Brentwood Drive
Southbridge, MA 01550
(508) 764-2072
emjones(at)charter.net

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