Challenge: design a (car) push button start schematic - General

A friend posed this question to me earlier today, and I've been mulling it over/ making some schematics to get it to work.. here's the idea: Take a normal key start car (assume to antitheft chipped key, for sake of ease) and convert it to a pushbutton start.. WITHOUT using extra switches. It should work like such: One press of the button turns on the ign/acc Pressing the button while holding the brake turns on acc/cranks the car Pressing the button a 2nd time after starting or turning on the ign/acc turns it off again. Now, here's my schematic; Pressing the button once latches one relay on, which then provides latched ground to a relay for acc and one of ign (more if there's more ign/acc wires, of course). That ign then feeds a delayed turn on circuit (cap/ transistor/ resistor), which takes some time (say, 10 seconds? based on cap size) before the transistor feeds ground to another relay. Once that transistor feeds ground to another relay it turns on, which flows 12v to one side of the coil of two more relays.... and when the push button is pressed again, these relays both get ground and activate, cutting the 2 ground wires that do the latching/ turning on the circuit. Finally, to crank, you need to press the brake, which puts 12v to one side of a relay, then when the button is pressed it energizes the starter circuit.. button needs to be held until car fires. Won't brake unless both the button and brakes are pressed, so no inadvertent grinding of the starter. [IMG]http://i22.photobucket.com/albums/b340/clutch1234/Pushbutton1-1.png[/IMG] So that's what I came up with. I don't know a thing about IC's and all that programmable jazz.. and I feel like those could be helpful (especially since I haven't even actually tested by delayed turn on portion of the circuit). Anyone else got any ways of doing it? :)

I bought a push button start from Ebay a while back for my keyed car. It took about 2 hours fiddling under the dash to get it to work, with the correct leads attached, and allowing the acc to be active as long as the brakes weren't pressed. 2 things I had to do: Disable the clutch safety switch by using a jump wire between the two contacts and eliminating the button on the back of the clutch rack. The other, was placing that same button behind the brake pedal, and then placing it in line with the 12v lead from the ignition to ground. The idea is almost exactly the same as yours, but when executed on my manual transmission car, you must still have the key in, and push both the clutch, and brake in (if it's in gear) to start. If you have it in Neutral the car will turn over without pushing the clutch, but due to the safety no longer being there, you can lurch the car with the starter if it's in gear, hence having to push it down. The button itself was maybe $20.00 and fit in a cigarette lighter location, and has a bunch of 10ft leads attached to it to run anywhere you desire. I was actually thinking of taking it a step further, so that you had to initialize another 12v system in the car to make it crank to make it take longer to steal. I.E. - a kill switch under the dash, or the +12vign attached to the remote lead of the subwoofer amp, and leave the "subwoofer off" option off, and then get in the car, turn to acc, then go into the radio options and turn the subwoofer on, or something of that nature.

Did you get one of the systems that was an actual module and all that jazz? That's What we're trying to avoid ;) made with straight relays and such. If we wanted to buy something he'd just buy up something like this: [url]http://www.ebay.com/itm/LT-E8B-Proximity-Sensing-Keyless-Push-Button-Start-System-/181000578722?pt=Car_Audio_Video&hash=item2a2479a6a2&vxp=mtr[/url] but that's no fun :P

[QUOTE=clutch2;39013413]Did you get one of the systems that was an actual module and all that jazz? That's What we're trying to avoid ;) made with straight relays and such. If we wanted to buy something he'd just buy up something like this: [url]http://www.ebay.com/itm/LT-E8B-Proximity-Sensing-Keyless-Push-Button-Start-System-/181000578722?pt=Car_Audio_Video&hash=item2a2479a6a2&vxp=mtr[/url] but that's no fun :P[/QUOTE] Nope, the one I bought was just a button, and I basically replaced the ignition function with it using different circuits in the car and mulling over a whole bunch of wiring schematics that made barely any sense (they used similar color wires for many systems). It was $20 as opposed to $330.

Dude you've got me itching for a deeper explanation of this! The bypassing clutch and so forth is the cake, but the latching ACC / crank only with brake that you achieved is the meat that we're after. Other relays or anything, or just a button?.. By having the key in were you using that to power ACC/ IGN like on an S2000, or was it simply to defeat the wheel lock, and the acc/ ign got powered up with the button itself?

The Honda S2000 is actually the idea I was going after, after finding a lot of forums where people literally installed the s2000 system in other cars, and as far as the brake goes, no relay - just a button on the circuit. Right behind the clutch is a button for enabling the start safety, and that's all it is, so I thought - why not just use the same thing on the brake. So, when the key is in, it functioned the ACC, IGNso the radio turns on, etc... I had a schematic on my PC for which systems I attached where, which I then printed out to install the actual button, but I am not able to locate it yet... this was like a year and a half ago.

You could just switch to voice activation. buttons were so 90's.

It's a state machine so that's how I'd treat it. Here's a sequence diagram: [img]http://www.websequencediagrams.com/cgi-bin/cdraw?lz=dGl0bGUgRW5naW5lIFN0YXJ0CgpPZmYtPkFDQzoACwYgUHJlc3NlZCwgTm8gQnJha2UAHAYAKQUAExEAHAUgSGVsZApBQ0MAASVDLT5PZmYAVBoAgRIFLT5JZ25pdGlvbgCBDwhPcgBmB1JlbGVhc2VkCgAaCCAtPiAAQBIK&s=napkin[/img]