Wireless Launch Control

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This is the bottom panel. Basic hardware holds the boards in place. The big screw at right middle is for all the ground wires.

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Another test fit. In the past I have left that gavlanized outlet cover unpainted (and the panel was also unpainted), and I have also painted it. It looks fine either way.

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Here's a bit of a segway. The field box top panel up to this point looks great, but after the last post and looking at the photo showing it mounted, I remembered I didn't really like the small gap on the right and left of the panel when it is in the field box. The gap is there because of the ribs on either side. The gap is the clearance. When this box was originally designed we were building out 8 field boxes for NSL 2008 and with everything else being built it was certainly more than good enough. But I like to tinker.

So I cleared off the table saw and made a mess. Cutting hardboard indoors always makes a mess. The first photo is the redesigned field box top panel. Not much is different except it is wider and has a few notches. Those are key. And the corner cuts have to be a little wider.

The second photo is the NEW fit of the panel in the field box. Not bad IMO.

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In case anyone is interested in how these are made. The first one in the prior post was a test and was cut by itself, obviously. But I wanted to use up the rest of my 2x4' hardboard panel. So I cut out some more.

The panel yielded 8 more blanks. All the same size of course. I taped together two gangs of 4 for cutting.

The second photo shows the cuts for the ribs. The first cut is centered, the others exactly 1-5/8" off center. 3/8" deep.

The wide notch along the bottom edge is rather tedious to cut. In the third photo I'm setting it up. The fourth photo shows some progress. This one is cut one blade width at a time. 4-3/16" x 1/2". Takes a few minutes.

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Juat a few more to finish things up. First photo shows the wide notch complete. Second photo I'm setting up for the 11/16" corner cuts.

Third photo is all done. Last shows all 9 blanks. The top one looks lighter because it is the prototype and I sanded all the extra pencil marks off the top.

Prototype and 8 boards took only 90 minutes (including photos). 10 minutes per board average. This is my new field box top panel.

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So now what? I'm going to re-do my field box top panels using the new design. Basically drill a bunch of holes--prime, sand, paint. That's going to take a few days.

The relay modules are mounted on the bottom panels already. Those aren't changing. So I can start with some of the wiring there.
 
Do you plan to replace or modify the hardboard in the old field box's with the new slotted and painted hardboard? I really like the look of these new tops. You do some great work.

Whoops... I guess you answered my question while I was typing.
 
If you're asking about replacing the panels in the club's existing field boxes then no, I'm in no rush to do that. But for my new boxes I do plan on using the new panels and not the older ones.

Attached is a pdf showing the new panel layout. Pretty much like before just a little wider.

View attachment Relay Box Top Panel 4 Pad Rev 2.1.pdf
 
Here we go again. Gang of two new version 2.1 field box top panels drilled. I'll spare the rest but basically just need to cut out the rectangle, sand, prime, paint.

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Finished the cutouts and a few more holes. Primed and drying.

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One more little update. These are the field box top panels painted. They still need to sit for a day or two but looking good.

I really like this new top panel design. I'm glad I did it.

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Oh it's dry enough to the touch. The usual rattle-can stuff. But if I start wielding tools and 12awg wires and all that around the top it's going to get all dinged up. Needs another day or so to dry properly. Preferably longer. But I can start working tomorrow or next day if I'm careful.
 
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What are the plans on using this new wireless setup? Just for the GRITS launch or for say... the G motor pad cell at our regular monthly launches.
 
No plans. SoAR owns the 4 pad wireless I built for them. They(we) will use it where they will.

This new system (8 pads) I'm building may or may not see light of day on a launch field. SoAR might use it sometimes, I might use it, or maybe I'll sell it and make another.

With the current form factor 8 pads scales to 16 pads pretty easily. Above that we're talking about a new enclosure. So the cost and time to deliver a larger system changes a lot. But it's doable.

So the answer to the question is, 'yes'.
 
I know of at least 1 club will to buy one if you consider selling them. I can't wait to see a 16 pad system if you decide to build one.
 
Here I'm starting to do some of the heavy wiring in the field box. Nothing fancy. 12ga wire between the power relays and the plug. 10ga would be better but I find the 12ga much easier to work with.

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Here I'm starting to do some of the heavy wiring in the field box. Nothing fancy. 12ga wire between the power relays and the plug. 10ga would be better but I find the 12ga much easier to work with.

Do you think there's a difference between 1mOhm/ft and 1.5mOhm per foot when doing this internal wiring? I realize all the voltage drop adds up within the igniter firing loop, but you'll only have significant current when the leads are shorted. In that case, it's good to have some distributed power dissipation especially if you're not including a thermal breaker. Besides, something like 16AWG is easier to assemble within a tight space. Just something to think about.
 
Two more showing the heavy wiring basically done. Just need to add the battery harness. The battery harness will connect to the top of the automotive relay and to the ground post. Now to repeat for the second box.

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The next and last set of wires to connect to the outlets is for the pad cable-end LEDs. Nothing fancy. They just connect to a header on the board. Also now the outlets can be secured to the panel.

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One more. This is the rest of the essential wiring. Not a whole lot going on. Power to the board, ground. Master arm to the relay. Heartbeat LED. Sonalert. The RCA connector for the beacon hangs off the MA relay. Still needs the battery harness.

What may be significant, if you have seen the innards of relay boxes before, is the lack of way more complex wiring. This is it. This box works.

The second photo is a detail I always forget. And did again. Supression diode on the external relays. Maybe I should put it on the main board and be done with it. Just a fast switching diode across the relay coil. Nothing special. If you arm the node and the CPU reboots, you forgot the diode. Duh. Edit: disarm actually. It's the coil field collapsing that creates the surge that needs to be supressed.

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Another diversion. After getting everything wired up nice and pretty, power up to test and the node would not sync to the master controller. But sometimes it seemed to work ok. Well that's inconvenient. Long story short I had to move the new relay boards to the test bed to figure it out.

The first photo is the field box with the relay module removed for troubleshooting. Nice to have some portability. Second photo is my test bed which sits on my computer table. Mainly for software development but it did help in this situation.

So bottom line is the super capacitors which are the backup power supply take a brief but distinct amount of time to charge. So the active components such as the relay module MCU and the wireless module will initialize when they will and at slightly different times.

My code, sometimes, apparently fails to detect the wireless module within a certain timeframe (very short) and defaults to wired point-to-point communication. Which doesn't work if communication is not point-to-point.

Easy to fix. Back to the build.

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The panel is back together and I've re-connected the RF cable. This is a 16" or so cable I had to fabricate myself because I had such a terrible time finding a source for short RP-SMA extension cables. They just don't exist.

An expensive part since the RP-SMA connectors are $4-$5 each, and plus I needed a $40 crimp tool to finish them. So be it.

The second photo is the field box basically complete. I tweaked the code so everything is working properly now. The connection to the external battery is still missing. And I need to do some labeling. But aside from that this product is ready to go out to the field and launch rockets.

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Multiple options for the external battery connection. In the past I have used plain old battery clips. The kind you find at Home Depot. And more recently Powerpole connectors. The issue is not so much the connector but how you connect to the box. Basically I have done the wires hanging out thing.

I've looked at alternatives but the price goes up. For example, in the photo there are 20A Powerpole connectors and 20A Powercon connectors. Same current rating. Big price difference. Like 10x+. Nice thing about the Powercon is the panel connector. No wires hanging out. Powerpole is simple, inexpensive. Plus Powerpole can go up in rating. Powercon tops out at 32A and that's a very expensive set.

So I'm doing the Powerpole. A 2 foot 12ga twin lead to a 20A Powerpole. And that connects to the battery. I'll post a photo when I actually do it. It will make more sense. Wires hanging out.

Anybody want a 20A Powercon connector?

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This is the battery harness. Nothing fancy since I am using the powerpole connectors. Second photo shows the box connected to a battery.

I know this thead is really slowing down. Time soon to wrap it up I think.

Was this useful to anyone?

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This is the battery harness. Nothing fancy since I am using the powerpole connectors. Second photo shows the box connected to a battery.

I know this thead is really slowing down. Time soon to wrap it up I think.

Was this useful to anyone?

Pretty cool.

Please give a field report when you get the opportunity.

Greg
 
I don't know when this specific box will hit the field, but I can say that this design has been in the field for awhile.

The wired version (prior version), a 32 pad configuration, has been supporting all our club launches, basically monthly, since summer/fall 2008.

The wireless version debuted at our GRITS regional launch last month. And all went well.

This build is a refinement on the prior wireless build. I'll probably build a few more. We'll see how that goes.
 
I built the second field box today. Identical to the first so no new pictures. Amazing how much faster the build goes when you don't stop to take a picture every step of the way. It still took a few hours.

It booted up just fine and started talking over wireless to the LCO controller like they were already best friends. I cristened it by igniting an eMatch.

I'll have a family portrait soon.
 
I made a few squibs and put them on the field box in the back yard. Then went up the road a hundred yards or so with the now highly mobile LCO controller. Check with observers and pop - pop -pop. Everything working good.
 
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