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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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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. |
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 |
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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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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 |
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 |
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. |
WigWag with BD Squadron Pro lights
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Ed Holyoke |
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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 |
Another option is to use either of these wig-wag flashers that are solid state and don't care about the loads if you go to lower power LED lamps. They do need an inrush limiter for lamps over 85W though -
http://www.periheliondesign.com/wigwagdmnl.htm http://www.periheliondesign.com/wigwagmnl.htm It is small enough to just clamp right behind the lighting switches on my panel - |
Still working to find the right resistance
Copy that Larry. I might try that flasher. My circuit has the flasher wired hot and the outputs switched per the 2 switch Aeroelectric drawing. Is the thing going to be clicking all the time if it isn't switched to a light? If it will flash one light at a time I'd have turn signals. That might come in handy for the occasional head on on the taxiway. ;-)
So, I had success with a pair of 75ohm 5w resistors in parallel on each side. Resistors ran kinda warm, but it did operate for 20 minutes with no hiccups. Then I went with 50ohm 10w and it works for about 2 minutes and then hangs and buzzes the flasher. I think the sweet spot is somewhere around 40ohms. That works out to .36 amps and about 5w. Ed Quote:
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Panel is already marked
Howdy Gil,
Already silkscreened my panel for 2 switches with w/w in the center position. Don't want to change that now. Ed Quote:
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Larry |
Hey Larry
PM sent
Ed |
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