Follow me home (generate DC Voltage for a specific period of time)

Thread Starter

Mitrut

Joined Feb 12, 2019
5
Hello guys! I'm quite new in electronics and I want to build myself a 'follow me home' module. This means when i unlock my car, the headligths should stay powered on for 10-15 sec. I was thinking that I can do this by connecting the car battery to the headlights when i unlock the car. But the problem is how can I turn off the lights automatically after 10 sec. -lets say-; i know its easier to buy this kind of thing but i want to build it myself. I will attach a video so that you guys can see what i was thinking about. Have a great time and thank you for your attention.

 

Alec_t

Joined Sep 17, 2013
11,406
Welcome to AAC!
Aren't the headlights controlled by the BCM computer? How will you interface safely and legally with that?
 

Thread Starter

Mitrut

Joined Feb 12, 2019
5
Welcome to AAC!
Aren't the headlights controlled by the BCM computer? How will you interface safely and legally with that?
Thank you for your warm welcoming! Newer cars can have this option activated. I own an older one just for playing with it ! Also, this is not illegal. It is related to the central locking of the car !
 

Thread Starter

Mitrut

Joined Feb 12, 2019
5
Well, you likely could but that would likely be more complicated.
So you need to find where the pulse from the remote is generated in the vehicle.
This won't be a problem, it's just a wire which has 12V for a short period of time. All that i want to do is to use the car battery for 10 sec. ( i was thinking about 555 timer but i'm not sure how to use it because i need a clock pulse as far as im concerned ). So, as long as I have the impulse from the locking sistem, the 'switch' between the battery and the lights should be on for a period of time.
 

crutschow

Joined Mar 14, 2008
25,123
You could use a 555 timer, but that's overkill for your needs.
Below the LTspice simulation of a simple, one MOSFET/relay circuit to generate the momentary operation of the relay (about 13.5 seconds in the simulation) upon receiving a pulse.
The ON time can be adjusted by changing the value of R1 and/or C1.
You will need to determine how to connect the relay contacts to apply power to the headlights.

upload_2019-2-12_20-46-58.png
 
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