I have a pair of led light bulbs on my car which draw 12v 0.5A power. I want these to gradually turn on when I power the leds and gradually turn off when they are switched off. The time for them to fade in/out should be between 3-4 seconds atleast. What type of circuit should I make for this.
The LEDs that I'm using are as follows with the gradual on/off feature on the white light only.
https://a.aliexpress.com/_mq7ZW2s

 

Since those lamps have integrated constant current drivers it may not be possible to dim them at all. The driver which is going to include some sort of DC-DC converter will have a particular frequency which will interact with PWM dimming and make the light flash.

You could test the lamps and see how they act on a variable power supply. If you can dim them by reducing the voltage without side effects then you might be able to work something out. I suspect, though, that you will find they have a narrow operating range and don't dim well or at all.

Can't tell until you try, of course; and you can't decide on a circuit until you know how the driver operates.

 

The constant current driver is only connected to the amber leds so that there is no hyper flash. The white leds have a seperate cable for power which does not run through the driver.

 

However I could still try the fade effect by tapping into the dome light as that has the gradual turn on/off effect from factory.

 

However I could still try the fade effect by tapping into the dome light as that has the gradual turn on/off effect from factory.

You do need to know if any dimming strategy will work, and which one(s). If they don't have a CC driver, PWM is the obvious candidate.

This might be a good option. They caution there will be a brief flash when first powering up the device but if the power is applied, there is no flash. This doesn't seem to be a problem in your application since you are not going to have to have the lights turn on when you first turn on the ignition.

 

LEDs, 555s, Flashers, and Light Chasers
chapter 12..Special LED Effects

 

You do need to know if any dimming strategy will work, and which one(s). If they don't have a CC driver, PWM is the obvious candidate.

This might be a good option. They caution there will be a brief flash when first powering up the device but if the power is applied, there is no flash. This doesn't seem to be a problem in your application since you are not going to have to have the lights turn on when you first turn on the ignition.

The slow on/slow off gives a nice impression of high quality like some German luxury cars - a bright flash at each power up will certainly be a deal killer - unless the new look at feel of luxury is "the desirable" 'loose wire/bad connection effect'

 

LEDs, 555s, Flashers, and Light Chasers
chapter 12..Special LED Effects

This driver can be PWM dimmed. It might be a good combination with a 555-based

 

Dimming and sow brightening might give the illusion of some quality, I find it obnoxious to have the ight come up sowy and fade away so that I am never sure that it wei switch off eventually. It makes no sense to me. An adjustable brightness can be useful, but not the fake "Luxury" gimmick..

 

You do need to know if any dimming strategy will work, and which one(s). If they don't have a CC driver, PWM is the obvious candidate.

This might be a good option. They caution there will be a brief flash when first powering up the device but if the power is applied, there is no flash. This doesn't seem to be a problem in your application since you are not going to have to have the lights turn on when you first turn on the ignition.

I'll probably end up buying this if every thing else fails. However, right now I am interested in DIY projects instead.
The way I have my LEDs set up, they turn on when I unlock the car and turn back off after 30seconds. They will also turn on when the car is in ignition, turning back off when I kill the ignition with a delay of 30 seconds

 

LEDs, 555s, Flashers, and Light Chasers
chapter 12..Special LED Effects

Hey, this looks perfect. Could you please tell me which capacitor and transistors should I use for the LEDs that I have considering they are more power hungry and that I want the fade effect to last for atleast 3-4 seconds

 

The larger the capacitor the longer it lasts, for your case I would use trial and error on small experiments to see what you want and what you like.