Designing a custom launch controller?

Ok...I got this from Radio Shack (really nice quality by the way), and I'm wondering...do I use the ground?

Mr Jello,

That switch has an led and a switch. You will wire +terminal of battery to power, -terminal of battery to ground, and the swtiched signal to ACC. Basically, when the switch is "on" the circuit between power and ACC is completed.

Kevin

Oh, I found this https://www.instructables.com/id/remote-model-rocket-ignitor/ which is using the same switch.

Kevin

Cool! Thanks so much. I'm not entirely sure how to use it in the "Arming Switch" section of this diagram though:

View attachment 108314

"Power" is on the right - connected to +.

"ACC" is on the left - connected to the rest of the circuit.

If you want the light on the switch to be on, then you wire the "ground" back to the - terminal of the battery. This isn't in your drawing but you can probably figure out how.

kevin

Green Jello said:

Cool! Thanks so much. I'm not entirely sure how to use it in the "Arming Switch" section of this diagram though:

View attachment 108314

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Hey, Mr. Jello,

There's a small problem in your circuit which isn't too hard to fix.

You have a yellow "battery on" light. This guy should not have a path to - terminal through the igniter. The reason is, you will only have the power light on when the igniter is installed. You really want the power light on no matter.

Kevin

kruland said:

Hey, Mr. Jello,

There's a small problem in your circuit which isn't too hard to fix.

You have a yellow "battery on" light. This guy should not have a path to - terminal through the igniter. The reason is, you will only have the power light on when the igniter is installed. You really want the power light on no matter.

Kevin

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That was the suggestion of Luke. I think that way it's a continuity light. I bought other LEDs to wire for power lights. Or maybe the light in the arming switch can be that one.

Green Jello said:

That was the suggestion of Luke. I think that way it's a continuity light. I bought other LEDs to wire for power lights. Or maybe the light in the arming switch can be that one.

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The continuity light is the red one on the left in parallel with the buzzer.

I don't know how the RadioShack switch is really wired - though I have one at home and will check it out tonight. It could be the LED (in the switch) is always on when there is power to the "Power" terminal. If this is the case, you can use that LED as the "battery is live" indicator. It could also be that the LED in the switch is only lite when the switch is "on". if that's the case, you can use this either as your continuity led, or as an indicator the controller is armed. Your choice.

Did you buy "12v LEDs" as well (which usually come with wires) or just the single components (which look like plastic bulbs with bare metal legs)?

Kevin

Use 18g "lamp cord" - it's stranded and flexible. You can buy it in bulk from Home Depot, Lowes, Ace. Get 40 feet or so. You want the battery on the ground - the controller in your hand, and your hand 30 feet or so from the rocket. Plus you'll have some waste.

Green Jello said:

What gauge wire should be used for this? I assume stranded copper as well?

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Very likely not - but it depends on what you're trying to do. 100' (the wire goes out and back) of 18g stranded wire has about .7ohms resistance. This does "eat" some of the power supplied by the battery which doesn't go into making the igniter burn. My opinion is you'll do just fine. You probably can't ignite a 50motor cluster, but all the normal stuff will work ok.

Why 50'? Safe launch distance for up to G motors is 30'. But for H motors it's 100'. I'm not going to argue with you if you want to be further back though.

Green Jello said:

Is there a run length issue with a 12V system like this? The Aerotech Interlock is 30' and I'd actually like to be even further away. I was thinking 50'.

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Good to know. I want to be further away now too. If you want to be 50' back, plan on having 55'-60' of wire between the controller and the clips. The wire will never be straight on the ground, and you'll want some slack on both ends to clip the igniter and lift the controller to a comfortable height.

Green Jello said:

Two reasons. One...most of the button pressing for launch is done by my 7 year old and he's still a little gun shy with the mid power motors. I won't ever use this for anything above a G. The other reason is this summer I had an Estes E9 blow up on the pad and it was so loud, one of my ears had hearing loss for 2 weeks.

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I can't give any voltage or amperage specifics, but mine works great with 100' of speaker wire. I use a small ATV/lawn tractor type battery, it's never had an issue lighting any igniter or cluster I've hooked to it. I usually never unroll the whole 100', but it's there if it's needed.

Hey Green,

I checked out my switch and this is what I found. The LED lights when the switch is "on" (closed) only. That is, when the cover is down and the switch off, the light is off. When the cover is up, and the switch on, the light is on.

There's a few ways to use this:

1) it could be your continuity light - but you would only know if there is continuity when the pad is armed.
2) it could be used for a general "hey it's armed" light. You would want to have a separate light for continuity.

Let me know how you want to use it, and I'll draw up a simple diagram of what to wire where.

Also, let me know what other components you have or features and I'll work them in there too. Do you want a "battery ok" light? Do you want a light or buzzer when the battery is hooked up backwards (this makes a differences when you use LEDs for the continuity light - the pad might be hot and you can launch, but the continuity light would never go on.)

One thing to think about, if you're waking 50' to the pad, you might want to know if you have continuity before walking back. This kind of feature could be added later with a little box containing a 9v. I can draw a circuit for you to think about.

Kevin

Green Jello said:

Is there a run length issue with a 12V system like this? The Aerotech Interlock is 30' and I'd actually like to be even further away. I was thinking 50'.

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I took mine and ran a wire from the launch system to a relay at the pad, there I have a kids 4-wheeler 12 volt battery which is switched on when I push the launch system button. Since I have done this, my rockets fire up very quickly compared to when I just ran a wire from the launch system, 50ft. out to the pad.

Green Jello said:

Luke, just to make sure in case it wasn't 100% obvious, I was joking about what you did to my crappy diagram. Thanks for the help.

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Hehehe... okay...

My "sarcasm meter" has been off-scale low lately...

Later! OL JR

Green Jello said:

That was the suggestion of Luke. I think that way it's a continuity light. I bought other LEDs to wire for power lights. Or maybe the light in the arming switch can be that one.

Click to expand...

Yep, that was my goof... sorry... in this configuration it WOULD work as a continuity light, but it would burn ANY TIME a good ignitor was connected to the system, as it is wired here...

Basically I was trying to keep the diagram as simple as possible, but didn't pay as much attention to what I should have been doing-- course fighting with the stupid paint program the whole time doesn't help.

Really you don't want it wired this way, because it will screw up the works... you don't want a continuity light to come on until you actually insert the safety key (throw the lock switch). Otherwise it just gets confusing... These things CAN be made overcomplicated...

I'll see if I can find my old diagram and post it...

Later! OL JR

Here's the pics... most of them anyway... Wiring diagrams and a component interior diagram of the (modified) Estes Electron Beam controller...

Disregard my previous hack job to Greenjello's diagram... :wink:

Hope this helps! OL JR

Green Jello said:

What gauge wire should be used for this? I assume stranded copper as well?

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Yep... I'd use "regular lamp cord"... it's cheap and readily available (a greenback at the Dollar Store will get you a 10-20 foot roll of the stuff). OR, I'd use between 12, 14, or 16 guage auto electrical wiring (standard size auto wiring for most applications). Multistrand can "technically" carry more electricity than single-strand, because the electrons physically move along the SURFACE of the wire; very little actually moves THROUGH it... (as I was taught in mechanic's school anyway) Besides, single strand wire is VERY stiff and will RAPIDLY work-harden from any bending or flexing and break (like bending a coat hangar back and forth over and over until it snaps.) Multistrand is usually quite flexible.

Later! OL JR

Green Jello said:

Is there a run length issue with a 12V system like this? The Aerotech Interlock is 30' and I'd actually like to be even further away. I was thinking 50'.

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Not really.... kicking it up to 12 volts on the supply side means you're delivering the same wattage to the ignitor with only have the amperage you would be with a 6 volt system. (volts times amps equals watts). The more amperage you push through a wire (current) the more resistance, or the larger the wire needs to be. Of course the longer the wire, the more resistance there is, and of course some voltage drop because of that (at the load, or ignitor) but basically if you're using a 12 volt system and lamp cord or extension cord, you can run a LONG lead without "running out of power" at the ignitor...

That's why I wired my controller with male/female standard 110 volt electrical lamp cord repair plugs, so that I can use a STANDARD 25-50 foot extension cord between the controller and the pad... That way, I don't have to roll up and store a HUGE mass of lamp cord around the controller and try to fit it in the box... I just have about 3 feet going to the battery, and another couple feet coming out to the pad, with a female plug on the end into which the extension cord plugs, and then a "clip whip" with the male cord plug on its end to plug into the extension cord near the pad, and the other end of it has the ignitor clips... When I'm ready to go, I unplug the clips cord from the extension cord, unplug the extension cord from the controller, plug the clip cord into the controller, and roll the four feet of the two lamp cords going to the battery and to the clips up around the controller, and put it in the toolbox (range box). The extension cord gets crochet-looped to prevent tangling and tossed into the back of the truck... easy peasy...

Later! OL JR

Green Jello said:

The last thing I need to get is a turn key switch. I looked at one place and they wanted $25 for one, so I hope they aren't all that much. The whole thing will be hooked up to a car jump battery just like I used the Aerotech Interlock.

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The only key switches I have found are pretty expensive. In mine I chose not to use one for just that reason. Instead I bought a mono headphone jack and mono headphone plug to use. In the headphone plug, you solder a wire bridge across the two terminals so it operates as a short. When the plug is in the jack, the circuit is complete.

Kevin

Green Jello said:

So something like this?

https://www.radioshack.com/product/index.jsp?productId=2103454

https://www.radioshack.com/product/index.jsp?productId=2062464

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The first one will work, the second is wrong. You need this:

https://www.radioshack.com/product/index.jsp?productId=2103992

I cobbled together this schematic which will work for you. The program I use (expressSCH) doesn't have that 3-prong switch thing, so I used a standard spst switch, drew an extra line and labelled the contacts.

Are you planning on soldering it, or using crimp connectors? If you are going to solder, you might want to twist the wires and test the schematic before committing I've never tried putting a "launching" light in the circuit, since leds draw about 20mA I can't imagine it would adversely effect the launch circuit.

Kevin

View attachment ExpressSCH.pdf