Car Immobilizer problem

[mechtronics]

just to get this straight so:

when u scan rfid ignition switch is active.?

this switch has to be still active in order to keep supply going through the relays.

and y do u have ignition switch connected to relay on c?

 

[amidis86]

Im sorry, i think you are misunderstand, the ignition wire from ignition s.w is another power to ignition coil, i cut it and put to C/NO so when the bottom relay hold, the engine can be start cranking

 

[amidis86]

Here, when ignition switch on, 12v will be go to rfid system circuit

 

[mechtronics]

ok so the rfid scanner latches the relay and you have a seprate ignition switch?

 

[mechtronics]

this is my view of the whole thing. diagram is a bit mess so take no notice.

basically u have a 12 volt signal as soon as u scan rfid which feeds relay.?

u can take this 12 volts and pop it straight into c of hold relay?

this 12 volt will supply 555 timer, as soon as 555 timer sees 12 volts it powers on and starts its 15 - 30 sec timing which instantly turns on relay in top right hand corner of pic.

this relay sends 12 volts from ur battery to the hold relay as you call it which outputs to ignition coil.

after 15 or 30 seconds or what ever time u have the 555 set to, it will shut off the top right hand corner relay and break the 12 volt battery power to hold relay. ?

 

[amidis86]

Yes it same like that, it the 555 can connect direct 12v or maybe need some resistor and transistor to active the relay?

 

[mechtronics]

no u wont need any transistors or any thing the only thing is ud need is a relay to operate at 12 volt around 30 mA, the 30 mA is to operate the relay via the 555 pin 3 output current. pin 3 will directly connect to the relay without additional components needed. basically the relay in the right hand corner will be your ignition cut off basically its you ignition switch.

 

[amidis86]

Thank, give me few minute to try this

 

[mechtronics]

have you got a 555 circuit diagram ya?

 

[mechtronics]

here is a circuit that would work for ya u might have to put in a variable resistor to have a suitable time delay that you want.

 

[mechtronics]

how is that going for ya?

 

[amidis86]

Hello i done with the ciruit, i used the component like in attachment. But the delay not long enough. What is CAP and VR value that can be adjust to delay 30-60second?

 

[(*steve*)]

Increase the size of the resistor or the capacitor or both.

Ignoring other factors (of which there are many), doubling the resistor value will double the time delay. Same with the capacitor.

At some point these other factors will cause this relationship to be broken, and somewhere further on the circuit will simply stop operating (actually, between these two points it will become unreliable in certain conditions (temperature, humidity etc.)

 

[amidis86]

Thank steve, i will try as you said.. i will update later

 

[Rleo6965]

Are you sure timer circuit was working? Pin4 Reset pin was tied to Pin2 Trigger. Your resetting the timer every time you trigger it. Tie pin4 to pin8 should be better.

 

[mechtronics]

try a 100k variable resistor 5 k is too little.

 

[mechtronics]

yes timer circuit is working no problem for me iv had it for ages. pin 4 is tied to pin 8 through a 10k resistor.

when circuit is switched on relay will turn on instantly for a given time. then turn off and stay off until the 555 circuit is switched off and on again.

 

[amidis86]

yes timer circuit is working no problem for me iv had it for ages. pin 4 is tied to pin 8 through a 10k resistor.

when circuit is switched on relay will turn on instantly for a given time. then turn off and stay off until the 555 circuit is switched off and on again.

So bad, there no more 100k vr on my case to test, need to walk awat buying a one.. Waiting is a pain....

 

[mechtronics]

what size variable resistors have u got??

 

[Rleo6965]

yes timer circuit is working no problem for me iv had it for ages. pin 4 is tied to pin 8 through a 10k resistor.

when circuit is switched on relay will turn on instantly for a given time. then turn off and stay off until the 555 circuit is switched off and on again.

Ooops. It's a Power On Delay Timer circuit. Did'nt notice earlier.

Try to use 47 ufd and 1.2Meg resistor combination for 60 seconds delay.