Homebuilt Launcher (including pics schematic)

The Rocketry Forum

Help Support The Rocketry Forum:

OverTheTop

Well-Known Member
Joined
Jul 10, 2007
Messages
3,864
Reaction score
1,162
Location
Melbourne Australia
G'day All,
In case anyone was looking at making a launch controller, here are some pics and a schematic of one I built as a first attempt. I think it was Tim from the MMRG that said it might be good for me to put some info up on the forum about mine. Maybe I did go a little "over the top" with some of the features, but I was having fun!

The unit is powered by 10 AA Nicad batteries. These have nice low internal resistance so can give out some decent current to the igniters. These are charged by a plugpack that plugs into the mains. Only a simple constant current charge, limited by resistor R1, is used. Overnight charging results in a fairly full set of cells. But don't leave it on for days at a time or the cells will suffer!

The cells have a resettable circuit breaker (see the left side of the box) in series to protect the system from inadvertent shorts anywhere.

The safety key is worn around the neck of the person prepping at the launch pad. When ready to launch, it is put in the switch and turned. Once this is activated it is possible to launch the rocket. Operating the keyswitch turns on an audible beeper that alerts all in the area that something is happening. Power is also fed to the strobe at the launch site so there is no guessing which bird is about to fly!

There is a continuity test circuit that proves there is a return circuit through the igniter. No green is no continuity. This is quite useful to find out if my daughter hasn't plugged the cable in properly!

The actual "Launch" switch is a hooded ("missile launch" style) spring toggle, so there is no chance of bumping it accidentally. The red hood needs to be lifted first, then the toggle can be pushed up to launch.

The cable/connector I used were some parts that I had around already. Multiple cables in parallel are used to reduce voltage drop and to provide some redundancy. The cable is just a little longer than the required safety distance so there is no guessing how far away you need to be from the pad.

Using 4mm banana sockets on the pad end of things give flexibility about whether I use "standard" alligator leads, or add more (piggy-back style), or have a special set of leads for cluster work. They are usually rated for over 10A or more so are a good choice for a few reasons.

The actual pad was machined, drilled and tapped from some scrap I had lying around. It's just a round piece of aluminium with a flat plate screwed on. The launch rod is screwed into this. This allows me to change rods as I need to in the future. The whole thing mounts on a standard camera tripod which makes for great adjustability. It is sporting my daughter's Estes Moondog in the attached picture.

Wiring inside the boxes was just done point-to-point, not using any PCB or veroboard.

I guess when I get some spare time I'll get some nice engraved escutchions for the front, but for now it works. Ah, so much to do, so little time...

Enjoy!







 

CharlaineC

Well-Known Member
Joined
Jan 19, 2009
Messages
1,098
Reaction score
4
This is great. I would sugest mounting the beaken onto the lunch pad as wit the audio warning system. Switch out the AA batery system and replace it with a 12volt gel cell battery ( the kind used in jup startpacks for car or for flight boxes for rc airplanes ) you could desin a secoundary strobe box that would sit half way from the launch pad and the launch control station. This strob box would also house the battery. Allowing you to connect the launch pad and the launch system to the strobe box. I Would also suges adding a secounday arming safty buttion. This would require you to hold down the button (wich would also set off the arming alarm) during the entire ignition sequence. It would also actas a safty if one trips or falls stopping accidenta ignition.
 

jj94

Well-Known Member
Joined
Jan 18, 2009
Messages
3,980
Reaction score
0
That looks great! Unfortunately, I can't read schematics and I have no idea of what the little symbol type things are.
 

OverTheTop

Well-Known Member
Joined
Jul 10, 2007
Messages
3,864
Reaction score
1,162
Location
Melbourne Australia
Thanks for looking and for your comments. Feel free to use my design as a base and work from it if you want. That's one of the reasons I posted it in detail.

Choice of switches, batteries etc, location of components is all up to the designer (what is preferred and available) and puts an individual signature on each project usually.

I personally think another button for launch verification would be a bit of an overkill on my unit as it has the "missile" style switch with a cover that is moved to get access to the toggle. An additional switch would be a good alternative if the missile style wasn't used (my opinion anyway!)

If you need to know what the schematic actually means, a book on basic electronics will get you going if you are interested, as will a friend who knows such stuff!

Stewart
 

flight4

Well-Known Member
Joined
Jan 21, 2009
Messages
671
Reaction score
0
Nicely done. Functional and lightweight. Thanks for the schematic.
 

shreadvector

Well-Known Member
Joined
Jan 19, 2009
Messages
9,004
Reaction score
187
Wow, another extremely nice controller posting. Looks fantastic.

My standard question: Can the key be removed when the system is "ON"? (The removeable interlock should never be able to be removed unless the system is dead/"OFF").
 

krypton21

Well-Known Member
Joined
Apr 26, 2007
Messages
105
Reaction score
0
I WANT ONE!!!!!

How much did it cost you to make it?
 

Race58

Well-Known Member
Joined
Sep 23, 2007
Messages
866
Reaction score
0
GREAT Job! I like it so much I think I'll build it. Thanks for sharing. I already have the camera tri-pod and was thinking along those lines anyway now you have convinced me.:)
 

Robert Davidson

Well-Known Member
Joined
Jan 21, 2009
Messages
120
Reaction score
0
Your setup looks great, but I have a question. Where did you get 9 pin serial cable that runs in 30 foot lengths? Wouldn't a 25 or 50 foot length of trailer wiring harness do instead. It's rated for 12 VDC and loads of amps.

Just need to pick up some socket ends and an extension at you local hardware place.

http://shop.easternmarine.com/index.cfm?fuseaction=catalog.prodInfo&productID=4986&categoryID=209

http://shop.easternmarine.com/index.cfm?fuseaction=catalog.prodInfo&productID=8055&categoryID=209

http://shop.easternmarine.com/index.cfm?fuseaction=catalog.prodInfo&productID=4987&categoryID=209

I wouldn't trust that flat ribbion cable. If there was any kind of short there'd be really nasty burn marks all up and down that serial cable.

I just thought of something else. If you hook directly into your vehicle trailer wiring harness (if you have one) you could launch your rocket by turning on the lights or by flipping the turn signal on. The safety key would be the one in your ignition. The one that doesn't pull out unless it's turned off. It would be funny to launch a rocket by hitting your brakes too. :)

4986.jpg


8055.jpg


4987.jpg
 

Indiana

Well-Known Member
Joined
Jan 18, 2009
Messages
1,226
Reaction score
0
Nice controller. I like the remote stobe "system armed" indicator.

Also, that is a nice solution for the continuity test circuit. What is the max recommended current for continuity testing ignitors such as Estes or Aerotech?
 

DaveCombs

Well-Known Member
Joined
Jan 19, 2009
Messages
3,066
Reaction score
3
It would be funny to launch a rocket by hitting your brakes too. :)
I would bet some small amount of money that your car's brake lights will come on when you press the brake pedal without the key ANYWHERE NEAR the car. So, you wouldn't want to use this as a safety.
 

Robert Davidson

Well-Known Member
Joined
Jan 21, 2009
Messages
120
Reaction score
0
I would bet some small amount of money that your car's brake lights will come on when you press the brake pedal without the key ANYWHERE NEAR the car. So, you wouldn't want to use this as a safety.

That occurred to me later. Plus there's those keyless entry keyfobs on people's key chains. They can honk the horn(for all clear) or turn on your lights (launch) as well without being near the vehicle.
 

Race58

Well-Known Member
Joined
Sep 23, 2007
Messages
866
Reaction score
0
Hi:
This is a great looking controller.
Do have any interior pictures or list of parts you used?
Lastly have you used it yet and if so how did it work for you?
Inquiring minds want to know.:D
G'day All,
In case anyone was looking at making a launch controller, here are some pics and a schematic of one I built as a first attempt. I think it was Tim from the MMRG that said it might be good for me to put some info up on the forum about mine. Maybe I did go a little "over the top" with some of the features, but I was having fun!

The unit is powered by 10 AA Nicad batteries. These have nice low internal resistance so can give out some decent current to the igniters. These are charged by a plugpack that plugs into the mains. Only a simple constant current charge, limited by resistor R1, is used. Overnight charging results in a fairly full set of cells. But don't leave it on for days at a time or the cells will suffer!

The cells have a resettable circuit breaker (see the left side of the box) in series to protect the system from inadvertent shorts anywhere.

The safety key is worn around the neck of the person prepping at the launch pad. When ready to launch, it is put in the switch and turned. Once this is activated it is possible to launch the rocket. Operating the keyswitch turns on an audible beeper that alerts all in the area that something is happening. Power is also fed to the strobe at the launch site so there is no guessing which bird is about to fly!

There is a continuity test circuit that proves there is a return circuit through the igniter. No green is no continuity. This is quite useful to find out if my daughter hasn't plugged the cable in properly!

The actual "Launch" switch is a hooded ("missile launch" style) spring toggle, so there is no chance of bumping it accidentally. The red hood needs to be lifted first, then the toggle can be pushed up to launch.

The cable/connector I used were some parts that I had around already. Multiple cables in parallel are used to reduce voltage drop and to provide some redundancy. The cable is just a little longer than the required safety distance so there is no guessing how far away you need to be from the pad.

Using 4mm banana sockets on the pad end of things give flexibility about whether I use "standard" alligator leads, or add more (piggy-back style), or have a special set of leads for cluster work. They are usually rated for over 10A or more so are a good choice for a few reasons.

The actual pad was machined, drilled and tapped from some scrap I had lying around. It's just a round piece of aluminium with a flat plate screwed on. The launch rod is screwed into this. This allows me to change rods as I need to in the future. The whole thing mounts on a standard camera tripod which makes for great adjustability. It is sporting my daughter's Estes Moondog in the attached picture.

Wiring inside the boxes was just done point-to-point, not using any PCB or veroboard.

I guess when I get some spare time I'll get some nice engraved escutchions for the front, but for now it works. Ah, so much to do, so little time...

Enjoy!







 

Handeman

Well-Known Member
TRF Supporter
Joined
Jan 18, 2009
Messages
7,680
Reaction score
263
Location
Stafford, VA
This sounds really good, but what happened to the pictures. All I'm getting is the little red X.
 

Race58

Well-Known Member
Joined
Sep 23, 2007
Messages
866
Reaction score
0
Yeah me too, I was getting them yesterday. Fortunately I saved copies of the pictures.:D
=Handeman;517584]This sounds really good, but what happened to the pictures. All I'm getting is the little red X.
Launch control 1.jpg


Launch control 2.jpg


Launch control 3.jpg


Launch control schematic.jpg
 

11bravo

Well-Known Member
Joined
Jan 19, 2009
Messages
2,738
Reaction score
0
This sounds really good, but what happened to the pictures. All I'm getting is the little red X.
At least you're getting them.
I get nothing and didn't yesterday either.
 

phatbob02

Active Member
Joined
Jan 6, 2008
Messages
44
Reaction score
1
Yeah me too, I was getting them yesterday. Fortunately I saved copies of the pictures.:D
I used a DB9 connector with a 12 volt system and fried everything.:cry: The ribbon cable is around 28 gage wire. I went to a 5 pin microphone connector and 18 gage 4 wire cable.
 

Attachments

rklapp

NAR# 109557
TRF Supporter
Joined
May 8, 2020
Messages
407
Reaction score
228
Location
Oahu, Hawaii
Tried the DIY controller yesterday with the speaker wires. I discovered it doesn't have enough current to ignite the motors. I finally sacrificed an extension cord and now the starters glow bright. Lesson learned...

 

neil_w

Hunkered down and slowly going crazy
TRF Supporter
Joined
Jul 14, 2015
Messages
9,110
Reaction score
2,422
Location
Northern NJ
Tried the DIY controller yesterday with the speaker wires. I discovered it doesn't have enough current to ignite the motors. I finally sacrificed an extension cord and now the starters glow bright. Lesson learned...
Just curious, what gauge was the speaker wire? An extension cord certainly works but there are thinner/lighter solutions if you find the extension cord too bulky.

You were really flirting with the edges of the park that day. :)
 

rklapp

NAR# 109557
TRF Supporter
Joined
May 8, 2020
Messages
407
Reaction score
228
Location
Oahu, Hawaii
Just curious, what gauge was the speaker wire? An extension cord certainly works but there are thinner/lighter solutions if you find the extension cord too bulky.

You were really flirting with the edges of the park that day. :)
I tried speaker wires from Amazon and it was crap so I sacrificed two extension cords. Someday I’ll find a better wire. Electronics are limited on the island after RS went away.

I have about 400ft to play with depending on the wind direction so I try out the wind and move to wherever seems appropriate. The goal is to avoid the monkey pod trees and canal.

1596261333303.jpeg
 
Top