Wireless Launch Control

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More like 'builds'. Yes and no. I appreciate your continued interest.

I've taken a segway in some ways. Working on other projects. Built a few rockets. Lately I have also been trying to finish the workbench in my basement. New top, and new pegboard for the tools and such. A project of several years off and on.

Over the summer I did order a mess of circuit boards to build a number of different configurations. I also ordered some top panels. I think I posted about those. The photo below is a stack of those circuit boards waiting for some attention. The second photo is the workbench project. As of today actually. The frames will be used up over the back of the bench to replace the temporary pegboards there now, and also cover that gap in the middle.

My new rocket builds all need paint and the workbench is still a work in progress, but I am also about ready to start putting parts on circuit boards again. Maybe by the new year.

The wireless launch control software is still a little bit buggy. I probably need to add some sort of prioritization scheme to the event handling. Even so it works great 99% of the time. But when it doesn't it really falls all over itself for a little while.

More to come. Cheerz.

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So a lot of time has passed and a lot of other projects done, time to start again on the next phase of this project.

Starting work on the 16 pad wireless controller. That's 4 clusters of 4 or 16 total. At the controller end that's 4 individual 4 pad modules.

There's really nothing special about this setup. Two independent 8 pad systems. One has the faceplate numbered 9-16. One of two.

Four PCBs built, many to go. These are the faceplates also.

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I remember reading you had some issues with the bugs in the system at one time. Did you get past that point?
 
I remember reading you had some issues with the bugs in the system at one time. Did you get past that point?

No not yet. But I will. It hasn't been a problem operationally. I have one system in the field, plus my own personal system which I test from time to time. All working ok.

The problem is only likely to appear with an inexperienced LCO. If one keeps flipping the enable switches and pushing the launch button repeatedly the system can experience a bit of brain freeze. Not normal usage. But it's still a problem and I'll work on it eventually.
 
That is awesome. I think a system like this would sell if it was made in volume. I think it might be useful for both pyro (fireworks) and rocketry.
 
Today's efforts. These boards are what I call LCO master controllers. Basically the wireless interface at the LCO end. Not much to them actually. Easy to build. It's basically a platform for a 40mhz CPU, and a wireless module plugs into the top.

Next I need six wireless modules. Not so easy to build. Two plug into these LCO modules. The rest go into field boxes.

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And a few more boards completed. Fronts and backs. These are wireless modules (as I call them) that act as a physical and electrical interface between the controller boards and the wireless modems. Not much more than a power supply, several indicators, and the mechanical connections.

A 16 pad system has two LCO controllers and four field boxes. So six of these are needed. Six wireless endpoints. This is where the cost really starts to go up. An 8 pad system only needed three.

Next are the relay controllers for the field boxes. Will need 4 of them. Big boards. Lots of small and large components.

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Another picture showing the wireless module connected to the LCO master controller. The double connectors on top are for the actual wireless modem. A similar arrangement will be found on the relay module that goes into the field box.

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Making some progress on the relay controller boards. But only on two of four boards so far. Obviously still missing are the four large power relays.

The third pic is the power section. The twin towers are two super capacitors that help keep the system powered and running even if the battery totally browns out during a launch initiation. Which happens.

As an aside, unfortunately my source for these great capacitors has dried up. I only have a few left. So I am looking elsewhere for them with little luck so far. I did find some smaller capacity ones that fit the same form factor. At about 1/3 the capacity they will power the circuit for 20-25 seconds vs 60-80 seconds for the larger ones. I like the larger ones.

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Finally done with the relay modules for 16 pads. Well almost. The one in the foreground shows the 40A power relays and 12awg terminal strip, but they're not soldered yet. It also shows the wireless module plugged in as well as the multipoint wireless modem on top. So you can see what that all looks like.

I really like this board because it does so much. Handles wired or wireless. For wired the RJ45 CatX plug can connect right to the board (3rd pic, center, is where the vertical RJ45 socket goes). For wireless obviously the daughterboards help a lot. Safety protocols are built in.

I like the power relays too. For low or mid power the terminal strip is a convenient place to connect 18awg or 16awg wires to whatever connector runs out to the pads. I like most people use an A/C outlet. 12v in, switched launch current out.

For mid or high power applications the best connections are to the spade terminals on top of the relays. Saves a few tenths of an ohm.

I'll probably take a break now. I'll have to program and test all the boards which takes a while. And I want to do some experimenting with LiPo vs Pb batteries at the pad end. I'd love to get a lighter weight/smaller LiPo inside the field boxes that will give a reliable day of low/mid power launching, or even high power. Vs the traditional (big and heavy) external Pb battery. Despite the clear cost advantage of the Pb battery.

So back in a few weeks.

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So I've been thinking about this LiPo thing. I bought a couple of 3.2Ah 3S 20C LiPo batteries and charged them up. 12+ volts fully charged, 11v or so nominal per specifications. They'll work fine for low and mid power. I want to put the batteries inside the field boxes. Nice and tidy.

But how to charge them.

Outside the box I have a smart balanced charger with an EC3 connector and a smaller 4 pin wire-to-board connector which taps the individual cells. So plug in the EC3, plug in the 4 pin connector and charge away. Below is a picture of the battery.

But I don't have easy access to the 4 pin connector when it is inside the field box.

So what I am thinking, is since the 4 pin connector is really 3 cell taps plus either ground or positive, I can use a mini stereo plug instead of the 4 pin which will be easy to install in the field box panel. And the ground or positive rail will be covered by the EC3 conection.

So it becomes a simple adapter cable problem which is easy.

Another option is to use two standard 2.5mm DC power entry connectors. And a pigtail adapter cable. Color coded, or maybe use a mix of .1 or .08 pin sizes for polarization. Still, getting the connections wrong could really mess up the battery if not noticed. I can also use a round DIN connector but that starts to get expensive.

Any thoughts about this from you who may know a lot more about RC battery charging and how it all really works under the covers???????

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I tested was built for fireworks. It worked well but would not do drag races. It used a 11.5 v 2.5 am 5o power the system and and 18.5 v 6 amp (?) battery to power the igniters. It lit every igniter I threw at it.

The problem I had was you could read the LEDs on it during the day so it appears the system would not power on during the day.

Chuck
 
I know a little more now about the the batteries but not much more about charging them. A 4S LiPo is nominal 14.8v which is good. A little more push for the ignitors. The price does go up.

If you're not a hardcore R/C racer, does it really matter if you balance the cells while charging? If you don't will battery performance still be "good enough"?
 
Balancing is needed when you more than one cell to prevent overcharging one cell. If you over charge one cell, you can destroy the battery and have a fire.
 
Balancing is needed when you more than one cell to prevent overcharging one cell. If you over charge one cell, you can destroy the battery and have a fire.

That much I understand. But anecdotal evidence suggests that a lot of R/Cers don't bother.

So I'm just wondering how important is it?
 
I have never had a fire or heard of one. I charge them in a fire resistant bag and never charge them my electronics.
 
Foremost, I love your controller; it's amazing.

When using lipos, IMHO, always balance the cells within .1 V per cell; it will prevent issues. This is not a proven theory, but having had a mid-air fire on an unbalanced pack, and a charge stand fire at the field, I just make it a rule.

Now, after several charger/balancer/adaptor trials, I've been using a Hyperion 15 series Duo, with great results. Zippy brand batteries from Hobbyking.com are also proven performers, and their price can't be beat.

Good luck with the wireless system.

PT
 
Agree on balancing. I would never chance it.

Flight4 have you though about selling kits to make the controllers.

I have to agree there things are fantastic. I would live to get my hans on one for our club. I may have to encourage the club to start saving.
 
Flight4 have you though about selling kits to make the controllers.

I do struggle with how to answer that question and others like it that I have received. I think the short answer is "no", at least for now. I'm just not in a position to provide a warranty or even support. Someone buying a kit or a built product will expect that.

The 8 pad wireless (LCO and field box) the way I build it costs about $1000 just for the parts. 16 pads like I am building now is twice that. Putting a kit together with detailed instructions will bump up that cost. No one in their right mind is going to make that kind of financial committment without some guarantee of support, at least.

Taking away the enclosure, custom milled and engraved panels, and rechargable batteries can reduce a kit cost quite a lot. But the basic problem is the same. My goals here are simply to entertain and inform, maybe inspire. Not to make a buck, or provide service.

If a serious hobbyist were to approach me privately about sharing schematics or parts lists or whatever I would consider that. I've done some of that already.
 
So I've been thinking about this LiPo thing. I bought a couple of 3.2Ah 3S 20C LiPo batteries and charged them up. 12+ volts fully charged, 11v or so nominal per specifications. They'll work fine for low and mid power. I want to put the batteries inside the field boxes. Nice and tidy.

But how to charge them.

Outside the box I have a smart balanced charger with an EC3 connector and a smaller 4 pin wire-to-board connector which taps the individual cells. So plug in the EC3, plug in the 4 pin connector and charge away. Below is a picture of the battery.

But I don't have easy access to the 4 pin connector when it is inside the field box.

So what I am thinking, is since the 4 pin connector is really 3 cell taps plus either ground or positive, I can use a mini stereo plug instead of the 4 pin which will be easy to install in the field box panel. And the ground or positive rail will be covered by the EC3 conection.

So it becomes a simple adapter cable problem which is easy.

Another option is to use two standard 2.5mm DC power entry connectors. And a pigtail adapter cable. Color coded, or maybe use a mix of .1 or .08 pin sizes for polarization. Still, getting the connections wrong could really mess up the battery if not noticed. I can also use a round DIN connector but that starts to get expensive.

Any thoughts about this from you who may know a lot more about RC battery charging and how it all really works under the covers???????

Your voltage indicated on lipo batteries is the low end--they charge up above that and you have to recharge before it reaches the indicated low volts in any one cell. You can use a balancer like this: 2-6 cells. Here's a good overview of the different types of batteries available: rchelicopterfun.

It will be difficult to tell how long a battery would last without recharging until you use it. I have to wonder if a lipo would last all day, but you can get chargers that work off a car battery in the field.
 
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The Pad 1-16 consoles are completed. MCUs (ten of them) are all programmed. Wireless is working. Pretty sweet.

Now onto building four field boxes (groan).

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neat stuff, great quality of workmanship

my 50c tho:
- i would use a dc/dc converter for controller power supply(5V down from 9.6V) costs a bit but you would get nearly twice the battery life, much better than a linear regulator with a block of aluminium, murata makes some good ones pin compadible with the 78xx series
- cluster select switch instead of countless leds and switches, much less panel space, less leds switches wiring and less pcb-s, might be a matter of taste, some like as many leds and switches as they can get
- i like to use more smd components and would much rather prefer pcbs with mask, especially for a outdoor equipment that is meant to last, corrosion will be a problem in years to come

everything can always be made better but this is pretty damn good job as far as hobbyist equipment goes
 
Thanks for the tip on the DC-DC converter!!! I had researched some of those when I needed 15v for a very early version of this project. But they were all the brick type. Tiny but still bricks. I had no idea they could be found in a TO220 form factor. Awesome.

Yep, and they are about 20x the cost of my little $.27 LM7805. But what the heck. And I hated that aluminium block heat sink. I'm not doing that this time. Of course the old 7805 is virtually indestructible. But they do run wicked hot. We'll see how these guys do.

I would really love to do a solder mask but it really pushes up the cost of the boards. And that's a big enough cost as it is. I have systems that have been in the field almost 4 years now, including ones that sit out in the wet grass, and the boards inside are as shiny now as they were new. I do scrub them down pretty good after soldering them to remove any flux. I think if I thought I had a problem I would probably use a brush on conformal coating to protect the circuits and electronics. Something to file away for later.

I guess I'm a 'like the switches and LEDs' type. Though I'm actually considering a second console that would sit next to the 8 pad LCO controller. It would have 8 or more switches and would in effect be a wireless 'bank' controller, literally. The existing LCO master board and wireless boards could be used with no rework up to 8, even 10 bank switches. With slight rework even more. That would be cool. And also cheaper than even a second Pads 9-16 controller. Software might be simpler too. Someday maybe.

Thanks for your comments.
 
I had to open one of my wireless field boxes today so I dropped in a 14.8v 3.2AH LiPo to try it out. Good news was it fits in the box just fine. I then tried a number of home made high power ignitors and most lit right up. I say most because one just exploded--but they do that now and then on a 12v Pb system too.

But of course it worked. It's a battery. Question is will it last all day, and if it doesn't, how do you quickly swap in a good battery? Still thinking on that.
 
Well r2kordmaa 's suggestion about the DC to DC converter was right on the mark!!! I have obtained a number of these from my usual component supplier and have retrofitted the current project. They work great! And where the standard regulator would get quite uncomfortably hot during operations, wasting a lot of energy along the way, the DC to DC converter doesn't even get warm. Love it. The pics are views of the converter in the circuits in place of the LM7805. :smile:

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David, should we consider "upgrading" our older main controller and field boxes with the DC to DC converter? And, um, yes....I follow this thread with great interest.:rolleyes:
 
David, should we consider "upgrading" our older main controller and field boxes with the DC to DC converter? And, um, yes....I follow this thread with great interest.:rolleyes:

Hey Jorge, I had no idea.:rolleyes: Only Kyle has made his presence known so far.

To answer your question, in my opinion, no. Two reasons why, again, imo.

The main controller has significant internal volume, plus is vented to the rear, so internal heating is less an issue than the new small wireless consoles which are basically sealed. It's why I put a aluminium bar heatsink in the 8 pad controller. Works great but I hated it. Better to be without it.

The modules in the main controller are the first design which is not wireless. So the regulator doesn't have to support wireless on top of the MCU and various LEDs. So significantly less current and therefore less heat dissipation.

Finally (ok a third thought), to do the swap every PCB would have to be removed so the regulator could be de-soldered and replaced with the converter. That's close to a complete disassembly of the system, field boxes included. The effort involved and time aside, there's some risk in doing that.
 
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