Muti-Launch Controller Drag Race Master Switch Wiring Question

I have a simple wired launch controller that I'm working on. I have a four launch system. For the power (+) to get there, you cut on a master toggle switch then another toggle switch to each pad that is going to be used. The 12V passes to main fire button for each pad then when pressed it goes to the pad. I want to wire in a master drag race button that will allow you to fire all rockets and the push of one button.

What I have in mind is hooking four separate wires to the relay out, then run each thru a diode then to each of the pad + wires so there want be any bleed over power between pads.

Any recommendations would be great! There is a lot more to the controller such as LEDS and Door Bell Chime, relay for master drag button, but I left it out to keep it simple. I need to hook one fire control button to four pads.

System is powered by 12V battery, it is not a relay launch system, it is built on the order of a Estes style controller, four in one with more safeties.

If the Diode idea is correct, then I need a recommendation on diodes to please.

It should be simple. The safety interlock and launch switch are on the high side and the output goes to all pads. The low side is controlled by pad select switches. Flip a pad select switch to select a pad and press the launch button to launch one or many.

That other stuff you haven't detailed complicates things but without any details, I can't say how much.

I agree with UhClem. Put the + from the battery, through the safety interlock, through the momentary Launch button, and split it off to the four pad select switches. Select as many pads as you want and push the momentary Launch button and the selected pads go. Don't complicate things with diodes etc.

I understand what is being said and agree that would be the simple way to go but I really keep the four fire buttons for the four pads because most of the time the kids at my elementary school love to fire their own rocket 90 to 95% of the time but every once and a while a single fire button for drag racing would be great.

Any workable ideas that will allow me to keep the four buttons and allow me to add the single drag race button?

You can do this with one or two relays without needing any diodes. I prefer the two relay system as it prevents arcing on all four contacts of RL2. RL2 is a 4 pole relay rated at 10 amps per contact. You could eliminate RL1 and connect S3 between S2 Drag contact and the coil of RL2. Add LEDs and continuity checks as needed. The second version allows you to select individual pads for drag as needed.

Steve G

Awesome, this is something I can sink my teeth into. Not sure what kind of relays and where to get them. I only have used to 30-60amp four and five terminal automotive style relays knowledge for the most part for launch pads and for 1/24 Scale Slot Car Tracks.

https://www.mouser.com/ProductDetai...=sGAEpiMZZMsqIr59i2oRcsUGyUJ4Rgtzc4FdlyZQaZE=

Use 4 or 5 terminal auto relay for RL1.

Steve G

sghioto, do you recommend a base for the 4 pole relay or just soldier the wires in direct?

I guess there is four in, four out, then comm ground and 12V switch connections?

10 terminals total?

I would solder all of those connections.

Steve G.

Thank you so very much! I will post some picks of the finished product at the end of the month.

For high current, both crimp and solder.

So, why bother with a drag race switch? Why not just flip up all the switches and press the fire button? Did I miss something?

Elementary School kids never press buttons at the same time. Most of the time we don't drag, but when we do, it will be nice! Also, I have a fire button called "fire missiles" for that.

Flash said:

Elementary School kids never press buttons at the same time. Most of the time we don't drag, but when we do, it will be nice! Also, I have a fire button called "fire missiles" for that.

Click to expand...

OK, I think I get it. You have an ARM button per pad *and* a momentary launch pushbutton per pad? And you want to add a button to launch all pads, bypassing the individual pushbuttons?

If that's the case, you don't need any relays. Just use double-pole switches for pad select switches. And another pushbutton to make them all go.

Thank you and yes you are right but I like the relay one the best, less load on the drag fire button which is rated at 5amps.

Flash said:

Thank you and yes you are right but I like the relay one the best, less load on the drag fire button which is rated at 5amps.

Click to expand...

You can get pushbuttons with higher ratings. Or add only one relay.

Thank you to everyone for your advice and help! I will post the project at the end of the month!

Here are some pics of that launch controller. Hope to finish it tomorrow. I will hit everyone with full details later to. Enjoy the picks for now, more to follow.

Five more picks of my new launch controller, The yellow cable is my 12ga 12V supply cable hookup and the two orange 50' cables run from the controller to the metal sawhorse four rocket launch pad. Each cable provides power to two launchers with one shared ground. They have male connectors on each end and will plug into two boxes on the sawhorse launcher.

With this launcher, you can fire one to four rockets at the touch of a button or click the three way switch to drag, select the number of pads you want and just hit the fire missile button and they all are gone in one hit.

I used 12ga coming on then almost 16ga the rest of the way besides the LED battery gage, door chime and Fire Missiles button.

Tested everything Monday, all was very good. The LEDs are plenty bright even in direct sun light along with the Main power toggle switch, only the Battery LED is hard to see, so I will be adding a hood to it.

The Sawhorse that I'm using for the four 1/8" rod launcher came from Home Depot and cost $34.95. I mounted two low profile electrical boxes to plug the two 50' cables from the controller to the pad. Each cable provides power for two rockets with shared ground. They have a nice weight and open up wider as the photo shows.

I have two of the four 1/8" rods mounted with two to go. They are removable for transport by unscrewing them since they are mounted to the 3/8" connectors.

I also tested up to four LEDs daisy chained with 12v and they didn't fire a Estes igniter, so they are super low amp for sure. Haven't tested a quest igniter yet.

I use two Aerotech pads, one with 3/16 and the other with 1/4 inch rods for larger stuff. I have adapter I can plug into the main cable when these pads are needed.

School launch is Saturday 16th.

Last pic of launch pad with all its parts besides blast defectors.

Looks good Flash. Nice work.

Thank you, thank you once again for your help. The system got its first full shake down today with our first school launch of this year and worked great. Only thing I need to do is change the All missiles fire switch power wire that lights it up to only come on when selected.

Thank you again.

I hate to tell you this, but that yellow cord is a suicide cord. What's to stop a kid from plugging that thing into a wall outlet and put those clips on something/one else? You said this is for students, that cord will be in your classroom some time or another.

Your orange ones look to have male plugs on both ends? Yikes.

I'm not a fan of using extension cords for launch controllers, I get that they are handy, and everyone has 'em, hell we had everyone bring all they had and put 500' of them together in April to run the away pad for one project, but still, not a fan.

Zonie said:

I hate to tell you this, but that yellow cord is a suicide cord. What's to stop a kid from plugging that thing into a wall outlet and put those clips on something/one else? You said this is for students, that cord will be in your classroom some time or another.

Your orange ones look to have male plugs on both ends? Yikes.

I'm not a fan of using extension cords for launch controllers, I get that they are handy, and everyone has 'em, hell we had everyone bring all they had and put 500' of them together in April to run the away pad for one project, but still, not a fan.

Click to expand...

Cords with double male wall receptacle ends are also known as widow makers.

When I built our club launch systems I used telephone cord, aka silver satin. A 2000 foot spool was only $87 at the time. I used standard RJ ends on it too. It's sufficient to carry enough current to power the relays. The only load carrying wires in my system are 14 ga. rubber insulated zip cord, permanently attached to the pad boxes.

widow makers .... only when 110V outlets are around. Wish we had those out on our field....
About as dangerous as a gun when there are no bullets....I guess you could use it as a club....

Without that risk, they are robust and cheap...
Hard to beat the price and reliability of 100' molded extension cords.

Oh...and the "suicide cord" is a staple on my electrician's workbench....as it was my fathers...
Like any tool -- in the wrong hands it can be dangerous.
Also like any tool - you should learn to respect it and us it properly.

Suicide cords are an (iffy) staple in INDUSTRIAL situations. Not Classrooms... The problem is that when the system is NOT on the field and stored where non authorized persons (kids) may possibly access it is where the problem lies. There are many reverse gender connectors that work for this application. I also use Phone cord. Cheap and easy to extend/repair.


You don't have 110V outlets on your range? We do. Inverters, Generators, etc. LOL.

A safe way around is to use only the neutral (white) and ground (green) wires when wiring up the receptacles and igniter clips.

Steve G.

This is a good idea so long as there is no connection on the black wire and it is sealed off.

I think he is using all three, as it looks like he is using hot for one channel, Neutral for the other, and Ground as a common.

I think he is using all three, as it looks like he is using hot for one channel, Neutral for the other, and Ground as a common.

Click to expand...

Correct! In this case he would need to install another duplex receptacle and use four cords for the igniters but can modify the 12 volt power cable. Just a thought.

Steve G.

Thanks for concerns, these are personal and not storage at school. They are bagged after use along with other launch equipment. I have since found out that 12V gel batteries like used in alarm systems work great. Did 126 rockets off one battery and it didn't drop below 13.0 volts. I have three of these, they use shielded terminal connectors, so I'm going to do away with the alligator clips and use the shielded female connectors in place of these. They connect better to these batteries than the over sized battery clips to.

Steve is correct about the orange 50' leads, one side (white lead) for one pad, one side (black lead) for the other and green is a shared ground for the two pads. I decided to just share the common or ground with only two pads and not all four, kind of gives me a back up ground if something goes wrong. I can also see the concern about the male ends on both cables. These aren't ever left or storage at school, they are packed into my large launch bag and taken home and storage in my building. No kids around the house, he has been gone 12 years now, he's 31 and is a Lic. electrician of all things

Thanks again for the advice.