Drag Race Stage-Tree Circuit

[Battleship]

Hello all:

I am trying to help a local high school out with their rocket car race day - they want to re-do their setup so that they are drag racing two rocket cars at the same time.

I was thinking it might be cool to build them a drag race staging-tree, and possibly even add a elapsed time counter and display to reflect total run time from start to finish of both cars. I was hoping to adapt existing L.E.D. circuits to drive larger high current flood lamps via opto-isolator coupler ICs and TRAIC drivers. Unforetunately, I have not seen any circuits that will perform the functionality I am looking for.

The pre-stage lights (amber)will be manually triggered via a simple momentary contact switch. These lights will stay lit for approximately 5 seconds, then triggering the staging lights (amber) which will light and stay lit until the operator triggers the start of the race (all rocket engines have been connected to their power supply and waiting for ignition spark). when the operator presses a START switch, the LED staging controller needs to light the LEDs in a pulsed pattern down the tree, staying lit for approximately 1-2 seconds each, until the final green "start of race" light is lit. The same pulse that is used to fire the green start-race LED will also initiate the triggering of the rocket engine power supply, firing the engines and sending the cars down the track. A IR LED trans/rec at the head of the track will be triggered and the elapsed time counter will start counting up, in 10 milisecond incriments, until the IR LED trans/rec pair at the end of the track stops the running clock, freezes the display until manually reset. I think most race enthusiasts get the idea. I had developed a pretty neat design for my boys scouts a few years back, but am unable to locate it now. All aspects of the circuit will be reset to their initial or default starting condition via a reset switch. Any suggestions or ideas on where I could obtain schematic and parts list info for such a project?

 

[Blueteeth]

A flow diagram would help put your idea's into something thats easier to make a circuit from. Driving lights/motors/power things is easy from logic signals, its the control part I assume you want to get right first. I'm thinking, for simplicity, a 555 timer with a 4017 decade counter. The decade counter can have multiple outputs tied together (with diodes) so that, say it changes state every 1.6 seconds.

Tying the first 3 together means this collective output would be 'high' for 3 x 1.6 = 4.8 seconds. Then the outputs that follow would be on for 1.6 seconds each. So first 3 tied together for your 'pre-stage lights', next three-5 are the cowntown lights (one at a time, moving down), the last of which can be the 'green go' light. The next output would connect to the 555 to stop it counting - so it just stops at green. Then the operator would need to hit a button to reset the entire thing.

As for a lap counter, thee are many pure logic (CMOS/HCTLL) counters on the web which may require a fair bit of wiring when compared to a microcontroller solution, but thats all they require - cheap, and cheerful. The above circuit could trogger the counter, and your IR/phototransistor pair could stop it. Dealing with two cars could be difficult, unless each is on a different track and can have its own opto sensor (just two ideantial timers, both started by the same signal, but each stopped by different beam breakers)

I doubt anyone is going to take everything you've said and take the time to create a schematic/parts list, so I fear you will have to pretty much design this yourself. However! Many here will provide guidance, and debugging problems, and answer questions.

As you've got a pretty clear idea of what you want, it makes life easier. So break it down into 'blocks', or modules. Creating the control signals is the most important thing as driving lights, be they 10mA, or 10A is relatively trivial, it just depends on using transistors/relays/FET's/triacs. As for cost, altohugh projects tend to always come up more than expected, a few logic chips, resistors, transistors, LED's can be had from even the smallest electornic store, and with Ebay's electronic shops, sahould be easy to get a big kit of all you need for next to nothing.

I mentioned a flow diagram at the begining because thats the sort of thing that not only gets engineers wet, but also is the language of logic state machines. And diagrams are king anyway Good luck.

 

[Battleship]

Thanks for getting back to me on this project Blueteeth.

Believe it or not, I had at one time designed, breadboarded, and tested a complete circuit for this project when I was working with my Boy Scout troop, for their pine wood derby track. I still have all the parts and components, as we were never able to finish the actual build before their meeting place became unavailable and they lost their charter. In fact, my design included many of the components you mentioned, which I assume are pretty standard items for this type of circuit; 4017B, 74193, 7400N, 74154, 45188CN, 4028B, 74192N, 74193, 4543B, 4011B, 556, etc.

The thing that burns my biscuit, is that I can't locate my diagrams, drawings and schematics. I found the parts and components, but all of my design work is missing. I guess I am just going to have to start from the ground-up with this project. Now, if I could only locate application spec sheets for the components I have assembled, the rest might be a bit easier to tackle. Thanks again - you will all be hearing from me soon as IU progress in this re-development project.