VansAirForceForums  
Home > VansAirForceForums

- POSTING RULES
- Donate yearly (please).
- Advertise in here!

- Today's Posts | Insert Pics


Go Back   VAF Forums > Main > RV General Discussion/News
Register FAQ Members List Calendar Search Today's Posts Mark Forums Read

Reply
 
Thread Tools Search this Thread Display Modes
  #271  
Old 04-06-2018, 12:50 PM
Aluminum Aluminum is offline
 
Join Date: Jul 2017
Location: San Jose, CA
Posts: 278
Default

Quote:
Originally Posted by rocketbob View Post
For the last few years I've been flying with the flashlight drop-ins in the -6 and like them. Far superior to the Baja's. At night with these lights I've had to land on our grass runway when the PCL box failed and didn't have a problem. There were noise problems initially but that problem has been completely solved.

The drop-ins being now used are these:

http://www.kaidomain.com/p/S025575.3...3T6-Flashlight

These units, coupled with an adjustable DC-DC converter set to 10.3V, operate noise-free:

http://a.co/eyWVBwd

Noise levels were validated with a spectrum analyzer.
Bob, is the reason for the DC-DC converter noise suppression?

I just received these inserts from Kaidomain (slow shipping) and they appear to be regulated internally for constant power. They kick in around 6V and draw over 3A, then drop down to 1.2A at 12V. It would seem that running them straight off the bus would produce less heat in the internal regulator?

I didn't try them at 14.8V yet.
__________________
Dan V
'91 Zodiac flying since 2013
RV-14A in progress
Reply With Quote
  #272  
Old 04-06-2018, 12:59 PM
rocketbob's Avatar
rocketbob rocketbob is offline
 
Join Date: Jun 2006
Location: 8I3
Posts: 3,564
Default

Quote:
Originally Posted by Aluminum View Post
Bob, is the reason for the DC-DC converter noise suppression?

I just received these inserts from Kaidomain (slow shipping) and they appear to be regulated internally for constant power. They kick in around 6V and draw over 3A, then drop down to 1.2A at 12V. It would seem that running them straight off the bus would produce less heat in the internal regulator?

I didn't try them at 14.8V yet.
Affirmative. They will run cooler also.
__________________

Please don't PM me! Email only!

Bob Japundza CFI A&PIA
N9187P PA-24-260B Comanche, flying
N678X F1 Rocket, under const.
N244BJ RV-6 "victim of SNF tornado" 1200+ hrs, rebuilding
N8155F C150 flying
N7925P PA-24-250 Comanche, restoring
Not a thing I own is stock.
Reply With Quote
  #273  
Old 04-06-2018, 01:03 PM
rocketbob's Avatar
rocketbob rocketbob is offline
 
Join Date: Jun 2006
Location: 8I3
Posts: 3,564
Default

Quote:
Originally Posted by Bill Boyd View Post
I'm looking to wig and wag, not just flash
Picky aren't we!

With the short wingspan of an RV flashing is good enough for me. Since you want to wig-wag you're getting above the $2.00 range.
__________________

Please don't PM me! Email only!

Bob Japundza CFI A&PIA
N9187P PA-24-260B Comanche, flying
N678X F1 Rocket, under const.
N244BJ RV-6 "victim of SNF tornado" 1200+ hrs, rebuilding
N8155F C150 flying
N7925P PA-24-250 Comanche, restoring
Not a thing I own is stock.
Reply With Quote
  #274  
Old 04-06-2018, 01:49 PM
Bill Boyd's Avatar
Bill Boyd Bill Boyd is offline
 
Join Date: Sep 2006
Location: Landing field "12VA"
Posts: 1,530
Default from the installation documents at Crazed Pilot

Pins 6 & 8 MUST be wired direct to the LED?s, no local
grounding of the LED?s is permitted or LED will not function!
__________________
Bill Boyd

Hop-Along Aerodrome (12VA)
RV-6A - N30YD - Built '98 / sold '20
RV-10 - N130YD reserved - under construction

donating monthly to the VAF - thanks, Doug
Reply With Quote
  #275  
Old 04-06-2018, 01:51 PM
Bill Boyd's Avatar
Bill Boyd Bill Boyd is offline
 
Join Date: Sep 2006
Location: Landing field "12VA"
Posts: 1,530
Default

Quote:
Originally Posted by rocketbob View Post
Picky aren't we!

With the short wingspan of an RV flashing is good enough for me. Since you want to wig-wag you're getting above the $2.00 range.
Shucks, mister... all I gots left is a dollar ninety-eight. That's the end of muh dreams.

ETA: the -10 wing is long enough that I'll have to modify the door to the hangar I built for the -6A just to get it to fit through. IOW it's long enough to cause problems.
__________________
Bill Boyd

Hop-Along Aerodrome (12VA)
RV-6A - N30YD - Built '98 / sold '20
RV-10 - N130YD reserved - under construction

donating monthly to the VAF - thanks, Doug

Last edited by Bill Boyd : 04-06-2018 at 01:53 PM.
Reply With Quote
  #276  
Old 04-07-2018, 01:40 PM
rv7charlie rv7charlie is offline
 
Join Date: May 2006
Location: Pocahontas MS
Posts: 3,884
Default

Just for a few data points. This has been a very long thread, so I might be repeating something already mentioned.

A reviewer on the Kaidomain site mentions exaggerated lumen ratings. No doubt these are very bright, but here's a link to the Cree XML-2 LEDs used in this lamp:
http://www.cree.com/led-components/p...te/xlamp-xm-l2

Cree rates each LED at around 500 lm (calculated; not measured) with a 2 amp drive current. The data sheet says max 3A drive current, but doesn't spec output at that level.

Forward voltage varies between 2.85V @ 700mA up to 3.3V @ 3A.

All the above numbers are per-device (3 devices in the product being discussed).

Based on Aluminum's recent post, it would appear that the product actually has in internal current-source driver for the LEDs, so we don't really know how much voltage is being applied to each LED. Does brightness seem to vary any if raised above the level that 'turns it on'? If not, there should be a 'sweet spot' of voltage fed into the product to minimize current and heat (the internal driver's most efficient operating point).

To the issue of local grounding: Most will probably get away with it; it almost always works with lights. But with switcher type power supplies, if the plane has, let's say less than ideal, grounding practices on the rest of the avionics, noise producers like old style strobes and newer stuff like switchers can push noise into other stuff via ground paths. There is lots of griping on this forum about LEDs causing noise in avionics, with little way of us knowing how the rest of the complainer's plane is wired. So an extra run of wire might not be a deal killer with that wig wag.

Charlie
Reply With Quote
  #277  
Old 04-07-2018, 03:29 PM
rv7charlie rv7charlie is offline
 
Join Date: May 2006
Location: Pocahontas MS
Posts: 3,884
Default

For the wigwag, try googling '555 wig wag flasher' & wander around the images section, if you're willing to do a bit of soldering. Here's one of the 1st I landed on; it includes a version using a SPDT relay (which is probably what I'd do; easy to handle any reasonable current), and a version that's all solid state, but only good for 5 watts or so of load.

https://www.spudstalker.ninja/electronics/wigwag/

Same circuit could probably be used with higher power transistors to do what you want, but spending a bit more time with the google would probably reveal one with the right components for higher power. You could build close to a dozen of those for $90 (plus labor, of course).
Reply With Quote
  #278  
Old 04-07-2018, 05:02 PM
Aluminum Aluminum is offline
 
Join Date: Jul 2017
Location: San Jose, CA
Posts: 278
Default

Quote:
Originally Posted by rv7charlie View Post
A reviewer on the Kaidomain site mentions exaggerated lumen ratings.
Gasp! Someone is lying on teh internetz!

These do draw about 14W per enclosure, which could produce about 1500 lm out of those Cree LEDs at nominal specs. If I were designing the controller, I'd run those LEDs in excess of nominal current at low duty cycle to squeeze out maximum light output within the heat removal budget. No, I don't have a high-speed camera to test this, but they sure are plenty bright. A halogen car headlight is 1200 lm at high beam. For $17 and change I'll take those lumens and laugh all the way to the bank (or AVGAS pump lol).


Quote:
Originally Posted by rv7charlie View Post
it would appear that the product actually has in internal current-source driver for the LEDs, so we don't really know how much voltage is being applied to each LED. Does brightness seem to vary any if raised above the level that 'turns it on'? If not, there should be a 'sweet spot' of voltage fed into the product to minimize current and heat (the internal driver's most efficient operating point).
No change in brightness from 12V down to 4V at input, at which point it abruptly turns off. Bob's experiments indicate 10.3V for sweet spot.
__________________
Dan V
'91 Zodiac flying since 2013
RV-14A in progress
Reply With Quote
  #279  
Old 04-24-2018, 04:13 PM
Paul Eckenroth Paul Eckenroth is offline
 
Join Date: Apr 2005
Posts: 102
Default

I am planning to use rocketbobs suggested Kaidomain flashlight heads and DC voltage adjuster along with Mike Bullocks Aeroelectric wiring schematic with added resistors for the LEDs. I have checked one of the lights with the voltage adjusted to 10.3 and ended with a heat sink temperature of 170 F after .5 hour. This seems pretty hot to me so I wanted to find out if this temperature is typical. Should the light survive running at this temperature. Also I am planning on 10 W, 50 Ohm resistors wired in parallel with the lights. Any advice on what type of resistor would be appreciated. Is this a substantial heat generator?

Paul
Reply With Quote
  #280  
Old 04-24-2018, 06:07 PM
rv7charlie rv7charlie is offline
 
Join Date: May 2006
Location: Pocahontas MS
Posts: 3,884
Default

If you parallel the resistor with the LED device and are feeding them with 10V, the power dissipated in the resistor is: E^2 /R, or 100/50=2 watts.

What's the reason for paralleling a resistor across the load? It increases power consumption, heat, and....well, that's it.

While there's a relationship between voltage and current, with LEDs you'd be better served to measure the current in the circuit than voltage. The data sheet (see link in previous posts) says the *max* current on that LED is 3 amps. But also note that none of the performance numbers on that sheet show anywhere near that much current. Max shown in the charts is 2 amps (2000mA). Note that if the LEDs are in series (they almost certainly are), the current in the circuit will remain the same whether there's one device or several in the circuit. What would change is the voltage, to maintain that current. That is the reason that LED drivers are current regulators instead of voltage regulators. (That basically means they vary voltage to hit their current setpoint.)

Charlie
Reply With Quote
Reply


Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

vB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Forum Jump


All times are GMT -6. The time now is 04:26 AM.


The VAFForums come to you courtesy Delta Romeo, LLC. By viewing and participating in them you agree to build your plane using standardized methods and practices and to fly it safely and in accordance with the laws governing the country you are located in.