push to trigger and stay on button help

hello everyone, before i ask my question i just wanted to say wonderful site!!

I'm making my car have a push to start ignition system, i have attached a quick draw that i have made

the way it works is like this:
you get in the car, flip a bulgin spst switch (in the picture i don't have a relay there, im probably gonna add one)
then you have to swipe a rfid fob, when you do that the rfid board will trigger a relay that will trigger 3 other relays for 15 seconds.
those 3 other relays trigger the starter wire accy wire and the ignition wire, from the car.
with the accy and ignition wires getting 12v the car is almost on
there is a momentary push button switch (Honda s2000 starter button) that must be pressed for a sec or two to get the engine running.

here is the deal, the rfid kit has a jumper to keep the relay on for 5 or 15 seconds, that means i have only 15 seconds to start the car and when i do start it, this means it will keep the car on for only 15 sec because it will close the relay after that, shutting down the car.

my question is what can i use to help me out, i want to use the rfid to trigger some sort of IC i guess, and then the IC will keep the relays on, so i guess an IC that can have a momentary button turn the relays on and keep them on....

the rfid board as 4 empty pins marked 5v gnd tx rx, im guessing that's the ttl serial for programing, maybe i can program the relay to stay on all the time instead of 5 or 15 seconds, just a thought though


thank you for your help
cheers
seesoe

Maybe something like the following:

http://www.discovercircuits.com/DJ-Circuits/4013oneshots.htm

that looks like the exact thing i need, but which one would i use? the top or bottom? if the bottom, whats the spare?
also just to triple check everything, with that i can use a momentary button to permanently turn something on?

seesoe said:

that looks like the exact thing i need, but which one would i use? the top or bottom?

Click to expand...

Use the bottom circuit.

seesoe said:

if the bottom, whats the spare?

Click to expand...

Spare - this is the wiring for the remaining pins on the 4013 IC. If you look at the actual circuit you can not find all the pins(1,3,4,5,6).

seesoe said:

also just to triple check everything, with that i can use a momentary button to permanently turn something on?

Click to expand...

Yes, it is designed for a momentary switch as described by the circuit symbol.

thanks!, sorry for the stupid questions but pin 1(q) and pin 13(q) can they be tied together? can i just leave pin 1 out? if so can i use pin 1 as the output instead of 13?

You can refer to the 4013 Datasheet:
DataSheet for 4013 Flip-Flop

Pin 1 and Pin 13 are two separate outputs from two flip-flop circuits in the IC and I wouldn't tie them together.

The 4013 has two Flip-Flop, the circuit uses the second one only. While it is possible to re-wire the device to use the first Flip-Flop, It would not buy you anything.

mmm, yeah i see, i was just wondering about that pin because i am drawing my schematic for the push button start, here is what i have so far

The green square with the 12V, Gnd, is this essentially a connection to your battery?

yes, this is the rfid board, the black and white wire is the 12v from the ignition harness, as of that diagram here is how it works

you flip a switch now the system is armed, you swipe a rfid tag and your car's radio, windows, fuel pump, ext... get turned on, then you can press the start button to start the car.

im looking now on how much power the rfid board will take on standby and i can just keep the main switch on

I think you ought to have a fuse in there to protect the IC and maybe even a Cap to suppress noise, but I'm not the expert on figuring that out for you.

i re did the setup, now the ic doesn't have to handle 3 relays just one, and that one will trigger the other 3, with a diode on pin 13 of the ic

got the suggestion from this site

www.cpemma.co.uk/flipflop.html said:

If you're wanting to switch a relay or other reactive load, a diode (eg, an ultrafast 1A 400v UF4004) should be connected across each pair of output terminals on rows 1 & 3, banded cathode end to +12v on row 1.

Click to expand...

Be careful because the ic 4013 is not able to substain the current required by your 3 relays.
Since you are already using relays, why not using an additional one in auto-retention in place of the ic.

Alberto

look at the picture in my last post i have an updated drawing where i made the ic drive one relay which will drive the 3 relays under it instead of the ic driving the 3 relays

what do you mean by auto-retention relay?

Even one relay is too much for ic 4013. It can drain max 3 mA and your heavy duty relay will need at least 150 mA each. If you will go with this ic you will need a transitor to drive relay.

(see datasheet for 4013 @ this link http://www2.toulouse.iufm.fr/iufm/Documentation/Solsire/4013.pdf )

Hope the attached schematic will help.

Alberto

ahha, i see, the relay however uses only aboutt 38ma, i see what you mean by auto-retention, but i can't use that method because of the way it needs to operate, it won't work nicely with the whole system., i'm going to have to read up on the transistor, it makes sense to put one to trigger the relay instead of the ic tirggering it, but im not sure how to use transistors.

i found this http://www.uoguelph.ca/~antoon/gadgets/relays/relays.html
figure 5, will that work? if so would R1 and Q1 be the same values?

here my current diagram I'm going to build

can someone please look over it change or suggest something perhaps if needed?
thanks everyone!!

I'm no EE, but I do design and build personal convinience devices for my own car. (and this forum has helped me repeatedly to that end.)
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IMO, there are a few problems with the design from a performance perspective:

-a pushbutton start should not simply activate the starter relay. The s2000 fails at this. A pushbutton start SHOULD simply be tapped, and the whole car startup routine should be taken care of. That is what Honda should have done.

-any convinience factor should INCREASE convinience, not decrease it. If you need a toggle switch, you may as well use your ignition switch. And if you are pulling out a key, you may as well turn the ignition a little more and you are there.

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So what do I recommend?

Fixing the first problem is easy. The best method to do this IMO is to add a remote start. These devices nearly always come with an "activate when grounded" wire. All you have to do is connect your s2000 button to this via ground and you are golden. Push the button and the car will go through the whole startup sequence.

This is more expensive (ballpark $50) but the performance enhancement is worth it.

This requires a remote start without a delay. Many remote starts will take 4 seconds to start which is just as unacceptable as having to hold down the push start till the engine cranks. So you'll need to shop around to find one that is instant start or 1-sec delay.

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By using a remote start, all that is left is how to hold on ACC, ACC2, and IGN. You've already got the circuit. The RFID output drives an LED and the latch. Why an LED? You'll want feedback so you know when the RFID was read. A 5 second LED flash is perfect. The latch circuit drives the transistor which drives three Bosch relay coils, activating ACC, ACC2, and IGN.

When you hit the brake pedal the remote start deactivates and resets but the car remains running because the latch holds IGN.

To stop the car, you'd swipe the RFID and the car will shut down entirely.

This method requires no toggle, no visible RFID antenna, and no car key. This method is also compatible with remote activation of the remote start. Simply get into the car after remote starting and swipe the RFID. Works the same way.

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THAT is the convinience package!

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FYI I personally believe the "better" "convinience" method is to shut down the car by pressing the s2000 button to shut off the three relays, and that is easy to do. But it is a terrible idea because your friends might get sticky fingers when you are doing 70 on the highway. Bad news! So the RFID it is =\. I'll bet there is a better way to shut down the car though.

By the way, I bought an "extended range" antenna from trossen (it was needed) and put it inside my seat cushion. The RFID was a keycard thinner than a credit card that stayed in my wallet. Which I keep in my back left pocket.

So the simple action of sitting in my car enabled the function of everything. But only MY arse could do it. Creativity counts for extra points . This solution might not be the best one to use in this case because sitting in the car would turn on all your accessories and keep them on during car crank. Bad for sensitive electronics. But it works for alternative methods, depending on how you interface all your gear. (I don't use a pushbutton start and my RS takes 4 seconds to hit the starter)