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06-02-2013, 09:46 AM
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Join Date: Jan 2011
Location: Carl Junction, MO
Posts: 172
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Resistor for wig wag flasher unit
Hello all,
I bought a simple flasher module from B&C and instructions call for a 75ohm 2 watt resistor to be used if led or hid lamps are used. I am using a hid landing light so I went to radio shack for this resistor. They don't have it of course. So I have questions. First, will a 1 watt 100 ohm resistor work? And two, why does the duck works hid lamp require one in the first place?
Thanks!
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06-02-2013, 10:33 AM
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Join Date: Nov 2005
Location: Asheville, NC
Posts: 2,692
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Quote:
Originally Posted by Kato's 8
instructions call for a 75ohm 2 watt resistor
will a 1 watt 100 ohm resistor work?
And two, why does the duck works hid lamp require one in the first place?
Thanks!
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The gents that made the instructions probably knew what they were doing.
I suggest following them.
The 75 ohm resistor specified will be loaded to approx 2 watts so the power callout is appropriate.
A 100 ohm would be approx 1.5 watts so a 1 watt is too small. Secondarily, it will allow less current to pass. I imagine there is a particular current needed (as would be inherent in an incandescent bulb and not replicated by LED and HID power supplies) for the flasher for it to do the switching. Bimetalic beam switches work on this principle although this unit could be solid state. The reduced current passed by the 100 ohm may not allow the flasher to work.
__________________
Bill Pendergrass
ME/AE '82
RV-7A: Flying since April 15, 2012. 850 hrs
YIO-360-M1B, mags, CS, GRT EX and WS H1s & A/P, Navworx
Unpainted, polished....kinda'... Eyeballin' vinyl really hard.
Yeah. The boss got a Silhouette Cameo 4 Xmas 2019.
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06-02-2013, 10:40 AM
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Join Date: Jan 2005
Location: NC25
Posts: 3,508
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What Bill said.
It is OK to get a resistor that has a HIGHER wattage rating but do not get one that has a lower wattage rating. Lower wattage rating will get HOT and may burn up like a fuse. A higher wattage rating will be cooler, larger in size, but still work.
Here is a link to a vendor that sales what you spec.
http://www.vetco.net/catalog/product...oducts_id=8610
Link to 75 Ohm 5 Watt Resistor.
http://www.vetco.net/catalog/product...att%20resistor
__________________
Gary A. Sobek
NC25 RV-6 Flying
3,400+ hours
Where is N157GS
Building RV-8 S/N: 80012
To most people, the sky is the limit.
To those who love aviation, the sky is home.
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06-02-2013, 11:13 AM
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Join Date: Sep 2012
Location: Omaha, NE (KMLE)
Posts: 2,247
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Mouser and Digikey will also have what you seek. The Digikey link is for a 5W chassis mount - just a little extra margin.
__________________
Dale
Omaha, NE
RV-12 # 222 N980KM "Screamin' Canary" (bought flying)
Fisher Celebrity (under construction)
Previous RV-7 project (sold)
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06-02-2013, 12:13 PM
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Join Date: Jul 2006
Location: Longmont, CO
Posts: 215
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Use 2 resistors in parallel
The previous posters are all correct, hover, you could use 2 1-watt resistors in parallel. Putting 2 150 ohm resistors in parallel will yield a 75 ohm resistance as seen by the circuit. Since they are in parallel, they each take half the current, so each of them could be 1 watt. Of course, this does add weight, but this is a solution that you could accomplish locally.
I am guessing that the resistor limits in rush current, but am not certain.
Send me a PM if you need further details.
David
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David Dalton
Longmont, CO
RV-7 Complete,
Flies like a dream!
Lifetime VAF Member
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06-02-2013, 12:24 PM
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Senior Curmudgeon
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Join Date: Sep 2005
Location: Dayton Airpark, NV A34
Posts: 15,420
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Quote:
Originally Posted by Kato's 8
And two, why does the duck works hid lamp require one in the first place?
Thanks!
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It is not the DW HID lamp that requires the resistor, it is the flasher unit that requires it when using the lower current lights like HID or LED. Picky distinction, but helps to understand how the system works. The resistors help load the flasher.
My guess is the flasher unit is using bi-metal switching or something functionally similar. Bi-metal strips bend in use, due to the heat generated by a high enough current going through them, and the bending action opens up a set of contact points. It is the open and closing of these contacts that make the wig and wag.
http://en.wikipedia.org/wiki/Bimetallic_strip
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Mike Starkey
VAF 909
Rv-10, N210LM.
Flying as of 12/4/2010
Phase 1 done, 2/4/2011 
Sold after 240+ wonderful hours of flight.
"Flying the airplane is more important than radioing your plight to a person on the ground incapable of understanding or doing anything about it."
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06-02-2013, 01:06 PM
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Join Date: Sep 2007
Location: BC
Posts: 1,674
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Hi Bill,
I just installed the BNC flasher with the resistors using HID (55watt) lamps. It works well but the resistors get pretty hot. You do not want to go down in wattage rating. Also, when installing the resistors, do not use any shrinkwrap over them to make a nice secure joint as the heat cannot get out fast enough.
I found the resistors online, and bought a bunch. Surprisingly, BNC doesn't sell them. Personally, I think they should include them with each flasher. Send me your address and I'll send you some.
Bevan
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RV7A Flying since 2015
O-360-A1F6 (parallel valve) 180HP
Dual P-mags
Precision F.I. with AP purge valve
Vinyl Wrapped Exterior
Grand Rapids EFIS
Located in western Canada
Last edited by Bevan : 06-02-2013 at 01:11 PM.
Reason: spelling
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06-02-2013, 02:39 PM
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Join Date: Jan 2007
Location: Billings, MT
Posts: 50
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Lower the resistor value, up the Watts
Bill,
I have had a lot of experience with this SSF-1 flasher from B&C. We have been using it in our panel builds for years. With the HID and LED's becoming so popular we began seeing issues using these flashers. They utilize the ground path thru the lamps filiment to WigWag. Although sold thru B&C this flasher was designed by Bob Nuckolls. He came up with the 75 ohm,2 Watt resistor to simulate the path to ground to activate the flasher. I have had problems with this value being low enough for the flasher to actually work. Last week I gave Bob a call and discussed this with him. We agreed on 50 ohm 10Watt was a better setup. The 75ohm 2 Watt just gets too hot and sometimes just won't cut it. I'd suggest verifying this with him if you are at all concerned, however this has been working for us.
Jason Smith
Aerotronics Inc.
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08-10-2016, 11:51 AM
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Join Date: Oct 2012
Location: LA, California
Posts: 323
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WigWag with BD Squadron Pro lights
Quote:
Originally Posted by Jason
Bill,
I have had a lot of experience with this SSF-1 flasher from B&C. We have been using it in our panel builds for years. With the HID and LED's becoming so popular we began seeing issues using these flashers. They utilize the ground path thru the lamps filiment to WigWag. Although sold thru B&C this flasher was designed by Bob Nuckolls. He came up with the 75 ohm,2 Watt resistor to simulate the path to ground to activate the flasher. I have had problems with this value being low enough for the flasher to actually work. Last week I gave Bob a call and discussed this with him. We agreed on 50 ohm 10Watt was a better setup. The 75ohm 2 Watt just gets too hot and sometimes just won't cut it. I'd suggest verifying this with him if you are at all concerned, however this has been working for us.
Jason Smith
Aerotronics Inc.
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To update an old thread - I'm using the Knuckolls designed wigwag circuit with a pair of Baja Designs 4300 lumen LED lights in Duckworks mounts. B&C doesn't seem to sell the flasher anymore. It is available at various places online. Search for Tridon EL 13A2 I was unable to get the lights to flash using his 75 ohm, 5w callout. I paralleled the resistors for 37.5 ohms and got solid flashing for the 20 minutes that I ran it. The resistors get too hot to grip between fingers but not too hot to touch lightly. I think it's a go. For the purists who think that it's a lot of wasted amperage, it calcs out to about a third of an amp on top of the 3.5a (measured) that the LED draws. That's not so much compared to the 100w halogens at 8 amps. I might buy some 50 ohm, 10w resistors to try out and save maybe a tenth of an amp, and likely run a little cooler.
Ed Holyoke
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09-01-2016, 01:26 PM
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Join Date: Oct 2013
Location: Schaumburg, IL
Posts: 5,298
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Quote:
Originally Posted by Bicyclops
To update an old thread - I'm using the Knuckolls designed wigwag circuit with a pair of Baja Designs 4300 lumen LED lights in Duckworks mounts. B&C doesn't seem to sell the flasher anymore. It is available at various places online. Search for Tridon EL 13A2 I was unable to get the lights to flash using his 75 ohm, 5w callout. I paralleled the resistors for 37.5 ohms and got solid flashing for the 20 minutes that I ran it. The resistors get too hot to grip between fingers but not too hot to touch lightly. I think it's a go. For the purists who think that it's a lot of wasted amperage, it calcs out to about a third of an amp on top of the 3.5a (measured) that the LED draws. That's not so much compared to the 100w halogens at 8 amps. I might buy some 50 ohm, 10w resistors to try out and save maybe a tenth of an amp, and likely run a little cooler.
Ed Holyoke
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I am using that same flasher (from amazon) with my Baja lights and resistors are not required if wired properly. this type of flasher, unlike traditional alternating flashers, does not use current to the light to activate the coil (most use a coil and not bi-metallic springs). It has a timer IC and transistor. It starts alternating as soon as you put 12 volts on the "X" input. You don't want the resistors if you don't need them, as they increase your current draw and produce heat.
Edit: I apologize, it was the EL13A2 that I replaced. It was a CEC X000S6CHHB flasher that operates as I describe above. The EL13 would require resistors.
Larry
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N64LR - RV-6A / IO-320, Flying as of 8/2015
N11LR - RV-10, Flying as of 12/2019
Last edited by lr172 : 09-01-2016 at 05:26 PM.
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