andrew.d.zachar(at)gmail.
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 Posted: Mon Oct 18, 2010 6:27 am Post subject: Rolling my own WigWag Circuit (with timer)...need help. |
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Warning: The following is LONG and may be borderline too clever and complicated for an OBAM airplane, but I'm having fun with the experiment for now...
(Also, you can read the following with embedded pictures/video at http://n999za.wordpress.com/2010/10/11/rolling-my-own-wig-wag-circuit/ and then http://n999za.wordpress.com/2010/10/17/wig-wag-fail/)
Let's get started.
Over the last couple months, I’ve been eyeing various landing and taxi light setups, trying to figure out what I want to do for my airplane. I’m not super keen on the leading edge landing/taxi light setup right now, so I want to focus on putting all the lights in the wingtips. There is a Van’s wingtip landing light kit that puts two MR16 sized bulbs in each wingtip. Supposedly, you can aim one set forward for landing (also recognition) lights, and aim the other set down for taxi. I’ve read on the forums that people haven’t been too thrilled with this setup using the standard 35W and 50W halogens that van’s provides (Is that what they provide?). Something about not getting enough light on the centerline of the aircraft, where you need it for landing. I have also read, however, that with the MR16 HID upgrades from somewhere like www.planelights.com or duckworksav.com, there is plenty of light to go around.
But then we come to wig-wag. I think wig-wag (pulsing lights) for the landing lights is a requirement safety wise (for me), so I am planning on incorporating a wig-wag circuit into my landing lights.
I could just wire them in parallel, so you turn the landing lights on, and either wig-wag them or not depending on wig-wag switch position, but because these are going to be HID bulbs, one needs to warm the bulbs up before pulsing. (I’ve read that 25 seconds was used previously on HID flashing circuits, so I’m going to use 30 seconds for now, but I may bump that up based on a crude bulb temperature test I may set up in the future.)
Procedurally, I could just wait 30 seconds after turning the landing lights on before turning on the other switch, pulsing them, but who can remember that 100% of the time? 30 seconds is just about the time it takes between turning the lights on for takeoff and liftoff. This is not the right time to be reaching down for another switch. I’d rather flip both switches ON, and have them automatically warm up before starting to pulse.
Enter xevision. They have a multiple-hundred-dollar HID flasher box that will work great for this application. Except I’m an engineer, and I love a good problem to solve, and I don’t have hundreds of dollars laying around for their unit. (And, I want to mess around a little with timer circuits, etc.)
Enter Microsoft Visio and B&C. Using Bob N’s Low Cost Wing Wag Alternative document (page 2.0) as a starting point, I drew up a concept for a landing and wig-wag circuit with a delay timer (haven’t figured out the timer circuit yet, but it’s just going to trigger a relay, so I’m going to simulate it with a switch for now).
Keep in mind, I could combine the functions into a 2-10 switch (similar to page 3.0 of the wig-wag document), but then I couldn’t use the switch-breaker I’m planning to use in place of the regular switch I have depicted. Maybe this circuit is a good candidate for an inline fuse…I’ll sort that out later.
Anyway, here’s the circuit for now (since I am a wiring novice, I’ll have to figure out how to connect 5 wires to one switch terminal later…I know you can’t just bolt them all on there.)
Oh, and I’ve shown the HID lights here as just normal lights. You get the idea, though.
http://n999za.files.wordpress.com/2010/10/wigwagproposal-off1.jpg
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Okay, for the first iteration (see next picture), I’ve turned on the LDG LT switch. +12VDC is now available through the switch, and is going to the following places: 1) to the timer circuit, starting the 30s timer (mechanism TBD), 2) The COM terminal on the SPDT Relay (and therefore through the NC terminal to both of the WIGWIG ON terminals of that switch), and 3) to both of the WIGWIG OFF terminals of that switch.
Summary, the 30s timer as started, and both landing lights are on steady.
[url=http://n999za.files.wordpress.com/2010/10/wigwagproposal-ldgonlessthan30.jpg]http://n999za.files.wordpress.com/2010/10/wigwagproposal-ldgonlessthan30.jpg
At this point, if we turn the WIGWAG switch ON (see next picture), the landing lights are still getting power, but through the NC terminals of the relay, so they are both still on steady. This is good, because we don’t want them to pulse before the 30s of warm up time as elapsed.
http://n999za.files.wordpress.com/2010/10/wigwagproposal-ldgonwwonlessthan30.jpg
Okay, let’s turn the WIGWAG switch back off, and let the 30 seconds elapse. Now. +12VDC is now available through the switch, and is going to the following places: 1) to the timer circuit, which has now closed the relay, 2) The COM terminal on the SPDT Relay (and therefore through the NO terminal to the SSF flasher, and then to both of the WIGWIG ON terminals of that switch), and 3) to both of the WIGWIG OFF terminals of that switch.
Summary, the 30s timer has elapsed, but since the WIGWAG switch is off, we are still getting steady lights.
http://n999za.files.wordpress.com/2010/10/wigwagproposal-ldgongreaterthan30.jpg
Finally, we move the WIGWAG switch to ON, and the lights are being powered through the LDG LT switch, the trigger relay, which closes the SPDT relay, the SSF flasher, and the WIGWAG switches ON terminals.
Summary. Pulsing lights.
http://n999za.files.wordpress.com/2010/10/wigwagproposal-ldgonwwongreaterthan30.jpg
Basically, the timer won’t let power go through the flasher until 30s after the landing lights are turned on.
A couple problems, though.
FAIL.
Okay, so maybe FAIL is a little strong.
Last week sometime (can’t remember when, it was a rough week at work), I ordered some things from B&C to make the wig-wag circuit I’ve been dreaming up.
Anyway, a small box with all my goodies appeared on Thursday, so of course I stayed up late trying to put my circuit together.
All I have as far as electrical tools is one of those $5 combination crimper/stripper tools that really sucks. After an hour of wiring, my hands were killing me, frustration levels were really high, and I made the decision that I needed both an automatic stripper (I hope that doesn’t set off the google search alarms) and a professional crimper. More on those later.
Anyway, that night, I ended up with this:
http://n999za.files.wordpress.com/2010/10/20101017-008-large.jpg
+14V will come in to the left, and the lights will be connected to the center terminals of the 2-3 switch in the picture. the fast-on connector at the top of the picture will eventually be connected to a timer circuit that will close the relay (top left) after 30 seconds.
Since I had never used a Stripmaster before tonight, I snagged this. (I'm sure everyone else on this list is familiar with them.
http://videos.videopress.com/21Myv62x/20101017-014_dvd.mp4
Pretty slick, huh? This is instead of about 60 seconds worth of stupid tool-knife-stupid tool-hurt hand-knife again-stupid tool just to strip one end of one wire.
Okay, let’s hook up my circuit.
This is LDG ON and WIGWAG OFF.
http://n999za.files.wordpress.com/2010/10/20101017-010-large.jpg
But. This is where bad stuff starting happening.
I threw the WIGWAG switch to ON and then used the simulated timer circuit to close the relay. Nothing happened (lights stayed on).
After a little more investigation, I figured out that both the normally open (NO) and normally closed (NC) contacts were getting +14V all the time (The NO contact was at +14V because it was being backfed through the flasher. I don't know if this is a problem or not yet. Maybe this is where I need some diodes.
During the investigation, I wanted to make sure that everything works as advertised.
I wired up the flasher from B&C. I not sure it’s working correctly.
http://videos.videopress.com/uTQKDDyA/20101017-015_dvd.mp4
It’s making a weird buzzing noise, and the first light comes on and starts to dim just as then the second one starts to come on, but it doesn’t really finish a singe cycle.
Finally, I bypassed the B&C flasher and checked the relay operation back in the original circuit.
First, I turn on the lights. Then, I turn on the wigwag, and the lights stay constant (simulating timer less than 30 seconds). Third, I’ll close the relay (simulating 30 seconds has elapsed) so current flows through the flasher (although since it’s not hooked up, the lights should turn off.) It works as I expected it to.
http://videos.videopress.com/Dufybbyc/20101017-019_dvd.mp4
Next steps:
1) Figure out if the B&C wig-wag module is working correctly and I am making some sort of error.
2) Once I get that working, hook it back up.
3) Order a 2-10 switch to do the same thing on one switch per my second drawing:
http://n999za.files.wordpress.com/2010/10/2-10wigwagproposal-off.jpg
Any comments? Ideas?
--
Andrew Zachar
andrew.d.zachar(at)gmail.com (andrew.d.zachar(at)gmail.com)
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