We've all seen the many instructables here already for rocket launchers. The bottom line of most of those is simply a combination of switches that will run a current to the igniter in the rocket engine. Some are more "classy than others, one is wirelessly operated by a cell phone (just a relay switch though) and so on. These are all great and simple, which is what many people want. However, I like to make things more complicated, "improving" them, as many people might say. So here are the specs of my rocket launcher:
- A 2 part system utilizing a circuit on the ground and an additional hand controller
- The two controllers are linked together by simple cabling ( originally i was going to use a 4 wire telephone cable, but my order was messed up and i was shipped some ethernet jacks instead. This is actually even better, and so it shall use a moderate length of ethernet cable.
- A "smart" arming and disarming system to ensure safety
- No microcontrollers, ICs, or anything else to confuse others. Simple parts that can be found around the workshop, some can be scavenged from taken apart electronic devices, and others to be bought cheaply.
- Somewhat simplistic design that most electronic enthusiasts should be able to understand
- Author who will respond to any comments, questions, problems... within 24 hours. Happy to help.
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Step 1: Prerequisites...
Just real quick, heres what i would know to make building this guy a lot easier.
Reading Schematics is a must
Knowing how to work with perfboard will be helpful.
Good soldering technique and experience is vital
Anyone who has a PCB workstation set up and wants to make PCB versions of this, let me know. I have many pcb layouts for the hand module and soon to be maybe a ground module too. Let me know, and of course leave pictures! The problem with this is that i use pad2pad, unlike most using eagle, so there might be some format issues but hopefully nothing to complicated.
As for tools, simple soldering equipment should suffice. As for me, I have a lot of it and I made that work out. As seen in the pics, it is fairly easy to get by on just the basic tool set. I laid out my entire tools for the pics. During work i only used about half of them here. Your call.
Step 2: Parts List
Most of this stuff can be obtained from Radioshack. I am not a fan of them, but i did make some purchases there a few years ago and had a few parts left over. I used those here.
Now as for the 2 circuits, I will be calling them the hand module and the ground module
Parts for Hand Module: (these would be thru hole with pc mount pins)
1 * ethernet jack (8 pins, preferably right angle, if not bend the pins like i did)
3 * LED (5mm, 1 each of red, yellow, and green)
1 * slide switch
2 * push switch (I am using standard 6mm tact switch)
3 * resistor (I am using 390 ohm, 1/2 watt. However, anything from 300 + should do the trick. Very important as we will be running the circuit from 9 volts.
Piece of perfboard
Parts for the Ground Module: (Some of these are panel mount, solder lug makes it easier, but if not just solder to the pins, no big deal.
1 * Keylock Switch ( I used one from Apem. Ideally it should be 2 position and the key is only removable in the off position. Mine can be removed in both but no problem there. Substitutable with Slide or Toggle Switch, SPST)
1 * Toggle Switch, SPDT (MIne had PC Pins, so i just soldered wires on and then put heat shrink on the connections)
2 * Push switch (Momentary, Normally Open Circuit. Preferably one with red and one with black actuator.)
2 * LED (5mm, one red and 1 green)
1 * Ethernet jack (same specs as above, but here needs to be vertical, not right angle
OK that was for the face of the ground box. For the inside you will need:
1 * 9v battery
1 * 9v battery snap
2 * resistor (same as above)
Relays: 1 * DPDT and 1 * SPDT or 3 * SPDT (Mine were from an assortment, they need to be able to run off 9 volts and if they have 5 pins that makes life so much easier.)
perfboard if you want...
Project box, i used empty box of gum (trident white comes in those cylindric cases... perfect for the job)
Step 3: !Animated Circuit!
I have this cool program where you can "experiment" with basic electronics stuff. Here is a pic by pic demo of how the circuit will work. Refer to the pics and don't skip anything.
Step 4: Getting Started With the Ground Module
Get the parts and refer the schematics. Every design made will be different, so a little improv goes a long way here. I am sorry to say that I do not have any pictures of myself actually making the device. However, it should be fairly easy. My approach was to solder small lengths of wire onto the PC pins or solder lugs of each component, then twist the wires together and solder those.
Here is some information to help understand how the this all works... The keylock switch is for power. Red LED goes on. Then the toggle switch is to "activate" all the components, really its just a second power switch. Switches to green LED.
There are 2 relays inside the module. When the red button is pressed, the DPDT relay "locks" into the up (normally open) position, and current can pass from the battery, keylock switch, toggle switch, DPDT relay, ethernet cable, to the slide switch in the hand module, to the launch button, and back to the ground module, 2 external alligator clip connections, and back to the battery ground terminal. There are 2 disarm buttons, the black pushbutton on the ground module and one of the tact switches on the hand module. When pushed, they activate the SPDT relay which breaks the connection and causes the DPDT relay to return to its down (normally closed) position.
Step 5: Adding On
This design takes a very literal approach to the term open source. It can be modified to fit your precise needs and criteria. The interface between the two modules gives a total of 8 connections, hence the term 8P8C connector. Almost each component such as the push switches and relays are directly connected to either the + 9v rail or ground. Now those two connections are available in the rj45 connector to power the leds. This means that only ONE additional wire is needed for each added switch or indicator led. Here are some examples:
>Want to know if the relays are "armed" ? Just make a connection to the DPDT relay terminal with the + connection, and then to an LED through a resistor. The ground connection is already available on the hand module.
>Want to know if the system is launching the firework or rocket? Just make that connection from where one of the alligator wires is soldered to the + connections, then again to ground. Again use LED with resistor
>Want to bring the arm switch to the hand module? Similar idea. make one connection to that power pin on the relay, but this time the other connection on the switch would be the +9v rail. The same thing for the disarm switch.
Just remember: switches use + rail, leds are grounded. And always use a resistor with the LEDS as 9 volts will burn them out in seconds!
Step 6: The Future of This Design...
Again, this is a basic idea of the design I have created. I was unable to get any pictures of myself actually soldering the components. For the base i soldered wires to the component pins and then to each other respectively. The hand module was made on a piece of perfboard. Later on, I hope to start working with PCBs and set up an area for etching in my basement.
In the previous step, I mentioned the capabilities to mod the design to suit personal preferences. It is unclear why i would want to arm it at the base, and then have only a disarm switch on the hand, but as i said the original version was for 4 wires and disarming seemed to be a higher priority. I also thought that the slide switch would prevent accidental depressions of the launch key but a simple short between two pins on the connector could easily bypass that.
And so I shall describe my ideal design dream: A 100% SMT PCB hand module design with arm, disarm, and launch tact switches, 1 slide switch for the other arming, and LEDs to show 'armed' (when the DPDT relay is powered, not just when the slide switch is up), 'launching'(when there is power at the external connections, through the relay com. and NO pins, not just when the launch switch is pressed, and finally a connection + LED to show the status of the SPDT disarming relay, even though its totally redundant, i just couldn't think of anything else.
Well, by my count that wil use 8 wires.
HOW TO LAUNCH: (the design shown here, if you have made a custom version this should not be necessary.)
Assuming your rocket/firework is set up already...Connect the two alligator clips to the igniter/fuse. Then actuate the switches in this order with these respective LEDS turning on/off.
Keylock switch, Red LED. then flip the toggle switch. Red LED off, Green LED on. Push red button, might here the relay click into the up position. It is now 'locked', press black button to unlock if needed. Plug in one end of cable.
For the hand module, bring it with the cable a safe distance away from the launch site, then plug the cable into the hand module. Red LED should go on. Slide switch up, yellow LED should also go on. Everything should now be ready + armed, press launch tact switch to set off rocket/firework
Congrats if everything worked!, if not look over the connections and if no luck leave a comment and i will reply soon. Disarm using the other tact switch and unplug the cable. Finish by unplugging from the ground module also, then flip the toggle, turn the key switch, and remove the key.
I have tested this by connecting a green LED with resistor to the alligator clips in the right direction. Everything works for me so far.. :). More to come includes a schematic as soon as I have the time to sit down and make one and more pictures as I plan to make a second build using the case shown below for the ground module. Built for a 9v battery and everything.. I like it.
As for the schematics, the picture in step 4 should be sufficient for now at least, just remember that the LED ground connection is the side that is directly connected to the wire at the bottom of the page/ - battery terminal, so u might have to follow the wiring a bit. Also remember to include a resistor ( not shown) between each of the LED negative pins and ground.
Please post any pics, videos, comments, questions, anything as I look forward to seeing the potential that the simplicity of this design could have. Good Luck.
Also, if anybody knows Yenka, I will be posting files to an animated circuit from there which will also double as a schematic. Its a lot easier to understand the works if you can see the simplicity of the design on a computer.