Another keyless start system

Thread Starter

Dlillard86

Joined Feb 14, 2020
3
I would like start by saying I've visited this forum over time and it's helped me greatly. That said I am not quite a beginner but definitely have a lot more to learn.

My current project can be purchased on Amazon but it's not exactly what I want so I'm planning to make my own system.
The project uses a RFID system behind my dash bezel in my old truck to "activate" the push button start system.
The system will use a single standard momentary push button on the dash. It will have four "modes."
Mode 1: Accessory power
Mode 2: Accessory power + ignition/run
Mode 3: Ignition/run + start
Mode 4: System off (to include reset of RFID biased relay
So push once for acc and push again for ignition. But if you press the button a third time it will turn off the system. Only when the brake pedal is depressed will it activate the start mode. Which I would like to be able to do once I set my fob near the RFID reader. This way I can get in, place my key fob, depress brake pedal, and press and hold the push button to start the truck. At point of release from the start mode it would need to have acc and ign/run active at this point to keep the truck in a running state.
I have explored thoughts of using flip-flops, biasing relays, momentary relays, and still I haven't been able to get things straight in my head to function the way I would like.
The complete system is using 12v dc. I would like to stay away from microprocessor control and like the idea of a modern system in a vintage truck using analog controls to accomplish it.

Any and all advice is greatly appreciated

Devin
 

Thread Starter

Dlillard86

Joined Feb 14, 2020
3
To be clear here as well, I'm not asking for someone to completely build this circuit for me. Just to help point me in a direction so I can continue on with it. I just wanted to provide as much info as possible to give everyone an idea what the end goal is.

Thanks again!!!
 

vu2nan

Joined Sep 11, 2014
189
Hi Devin,

Your start system may be easily configured using electromagnetic relays suitable for automotive applications (vis-a-vis voltage/current rating, Lucar connectors etc.).

Regards,

Nandu.
 
Last edited:

Thread Starter

Dlillard86

Joined Feb 14, 2020
3
Hi Devin,

Your start system may be easily configured using magnetic latch relays which are also available in automotive versions (vis-a-vis voltage/current rating, Lucar connectors etc.).

Regards,

Nandu.
I had been looking into using said relays but each time I ran into the issue of getting past the constrictions of 4 modes. Truly 3 modes is actually what's been giving me headaches but I think I found something to make it a bit easier on me. I never knew the 4017 decade counter existed. Tomorrow I will sit down and try to draw up a schematic for my goal here.

Thank you for your response.
 

vu2nan

Joined Sep 11, 2014
189
Anytime, Devin.

The required number of relays for relay logic would be 8 maximum.

Here's to your arriving at the optimal solution!

Regards,

Nandu.
 

cndg

Joined Mar 31, 2013
6
Did you sort this out yet? The "logic" of what you're trying to do is exceptionally simple - an arduino "brain" would suit perfectly, with some relays for the output and a simple NFC receiver for the input. If you don't know "arduino", most schools teach it, so snag any friendly teenager off the street and ask - it's about an hours programming work for anyone (5 mins for a pro).
 
How about like a CD4017 decade counter and a couple set / reset latches (CD4043)? The parts are just quick searches so I'm sure there's better.

Here's my thinking... On the counter Output 0 could be all off. 1 - sets ACC latch to toggle relay. 2 - sets IGN latch to toggle relay. Maybe an AND gate that make it so output 3 latch (IGN) needs to be on while the button is pressed to activate starter relay, Output 4 to the reset line of the counter and the latches. Your button would be the clock signal (with a debouncing RC setup) to the counter.

Just realized how old this was...
 
Last edited:

MisterBill2

Joined Jan 23, 2018
9,797
How about like a CD4017 decade counter and a couple set / reset latches (CD4043)? The parts are just quick searches so I'm sure there's better.

Here's my thinking... On the counter Output 0 could be all off. 1 - sets ACC latch to toggle relay. 2 - sets IGN latch to toggle relay. Maybe an AND gate that make it so output 3 latch (IGN) needs to be on while the button is pressed to activate starter relay, Output 4 to the reset line of the counter and the latches. Your button would be the clock signal (with a debouncing RC setup) to the counter.

Just realized how old this was...
I also observed that this is a very old posting.
WHAT HAPPENS to cause them to appear???
 

MisterBill2

Joined Jan 23, 2018
9,797
New members is the simple answer. Or older members looking at how to do a new project. Both would do a forum search for what their after. I seem to remember you necroposting at least one time, maybe more.
That was probably before I started looking at the dates. And yes, possibly I had been searching a specific topic. I have done that a few times.
 
Top