12vdc Pulse Timer

[Hochstrasse]

Hello Everyone,

I am looking for a schematic to build a 12vdc Timer with a +12vdc output with a 3-4 second +12vdc ON delay
from a +12vdc pulse. I am trying to build a LED cornering lamp timer.
If anyone can help me I would greatly appreciate it.
Thanks in advance for your help.
Mike (Hochstrasse)

 

[Martaine2005]

Hi Hochstrasse, not sur I have heard of that before...Do you mean a 12volt auto turning indicator?

Sorry about that, you know us across the pond are are little slow....

 

[AnalogKid]

When you say "on delay", do you mean:

1. +12 appears, nothing happens for 4 seconds, then lamp comes on. In this case, what turns off the lamp?

2. +12 appears, lamp comes on, 4 seconds later lamp goes off.

Is the 12 VDC pulse a signal that is separate from the power source for the lamp?

What is the lamp current?

ak

 

[Kiwi]

Cornering lights are fitted to vehicles to light up the dark area, not illuminated by your headlights, that you are turning into at night, eg into a driveway. I wish my car had them when entering my narrow driveway.

I would guess that he is trying to use the 12v pulses to the indicator lamps to turn on a timer that will operate the cornering lights. The timer is set for 3 seconds, so will stay on between flashes. Each flash of the indicators will reset the timer for another 3 seconds to keep the cornering lights on. The timer will turn off 3 seconds after the indicators stop.

Should be possible with a 555. Might see if I have one to play with.

 

[Martaine2005]

Cornering lights are fitted to vehicles to light up the dark area, not illuminated by your headlights

Thanks Kiwi, makes perfect sense now. And a great idea.
I would prefer the 'cornering lights' be to be on the whole time the indicator is on. Easily achieved by using another relay activated with the flasher relay.
But the OP doesn't want that.
Martin

 

[Kiwi]

Martin, I don't think you have quite grasped the problem in fitting cornering lights to a vehicle yet.

"I would prefer the 'cornering lights' be to be on the whole time the indicator is on." The timer will keep the cornering lights on from when the indicators flash for the first time, until 3 seconds after they flash for the last time.

"Easily achieved by using another relay activated with the flasher relay." The extra relay will just flash on and off at the same time as the indicators.

 

[(*steve*)]

The extra relay will just flash on and off at the same time as the indicators.

Not if it's powered from the signal sent to the indicator relay from the indicator switch.

 

[Kiwi]

In the standard vehicle indicator light system there is no signal sent from the indicator switch to the indicator relay(flasher unit).
The switch is connected after the flasher unit and simply connects the flasher unit output to the left or right indicator lights, depending on which way the switch is moved.
See this very basic diagram.

 

[Martaine2005]

Yes Kiwi, you are right.
I just had a good read up on the 12v vehicle wiring.
The relay has constant power supplied.

I thought that the relay was powered from a switch and could be tapped from there.
Martin.

 

[(*steve*)]

My car must have double pole switches on the indicator control then... (it has cornering lights)

edit: More likely perhaps is that it has the indicator switch on the ground side of the indicator lamps, but I don't have a manual to confirm that and I'm not pulling things apart to find out :-D

 

[Martaine2005]

My car must have double pole switches on the indicator control then... (it has cornering lights)

edit: More likely perhaps is that it has the indicator switch on the ground side of the indicator lamps, but I don't have a manual to confirm that and I'm not pulling things apart to find out :-D

Aww. go on Steve, (EEVblog) Don't plug it in. Take it apart....

 

[hevans1944]

Either way, a diode on each indicator lamp to detect and steer the turn signal to added circuitry for the timing delay and to activate the cornering lamps should work. Do both cornering lamps come on at the same time, or just the one in the direction being turned into?

 

[Kiwi]

The diagram I posted above is a very basic system.
There have been all sorts of variations to the indicator system, eg using the rear orange indicator lights as reverse lights, using the rear red indicator lights as brake lights(USA), sequential rear indicator lights(Ford Mustang).

Steve, your car could have a double contact switch, or it may have a module to control all the lighting. Some of the latest cars have very complicated computer controlled systems with several modules spread throughout the car.

Howard, the cornering lights only work in the direction you are turning when the headlights are on.

 

[hevans1944]

@Kiwi So how do you determine the headlights are on? Are the cornering lamps powered from the same circuit that provides power to the headlights? Why is this supposedly a difficult problem? I will admit I know virtually nothing about modern automobile wiring. The last thing I actually worked on was the electromechanical kludge that Ford/Mercury used to implement sequential turn signals at the rear end of my '68 Mercury Cougar XR7. What a POS that was.

 

[Martaine2005]

OK, to revive this thread. Even though the OP has not replied.
I found a solution and it works.
@hevans1944

So how do you determine the headlights are on?

I used the side lights power to supply the relay. pin 87. So only powered when lights are on.
Supply from flasher relay to diode and capacitor (largest I had 6800uf). Pin 85. And pin 86 to chassis ground. But works either way. 86 ground or 85.
And pin 30 to another bulb (the cornering light).
Works a treat.. Although a larger cap will have a longer 'ON' time.
Also works both ways with pins 30 and 87 too.
Martin

 

[Martaine2005]

My solution above, also needs a relay on both left and right though..May be a problem for the OP but is extremely simple..
Martin