Interior light timer/dimmer

Because it's pointless.

You're right, looks like I forgot everything I ever knew...

...although I notice I'm the only one to post a link to a working circuit ;-)

Wooo! a BTEC.....

Isn't that what they send the bottom quartile to do whilst the rest go and do A-Levels?

Well in this case the fact that if you put a cap in series with a light bulb then the bulb will flash on so briefly you won't notice it. If you put it in parallel it won't do anything at all on on & a 10000uF cap will run a 5W bulb for a couple of milliseconds on off.

True mainly CBA to search one out in my case. What you need is something like a model railway tain controller. Specifically one of the controllers that includes inertia. Yup something like that.

Never liked the analogue stuff anyway, that's why I went on to computers, microcontrollers and stuff.

Now give me a PIC to handle the courtesy light and you'd be *amazed* what it could do!

More than what you have as I recall...

Apart from the fact it's classed as two A levels...

Incorrect.

A whole two. Wow.

Mind you, that's what they always say about 'vocational' courses for the hard of thinking.

I'm almost certainly going to have to go down the PWM route. I want a nice slow linear fade in and out. The actual time delay isn't a problem. But I obviously want to keep quiescent current to a minimum.

You won't get a standard car bulb to fade up to full brightness then fade down again using only passive components. Even with a degree. ;-)

Lots of such things are pointless to one person but not to another. And since most decent modern cars do this trick the designers obviously think there's a point to it.

BTW - it's often nice to do something just because you want to.

Ok then, a bulb, a cap, a 10KOhm vr and a 12v power source. Put em together and bang the video on youTube so you can prove us all wrong.

Thanks - but that's just one of the many delay and fade out circuits around. I want a fade in too.

That one does fade in as well. Change the 10K to something higher to reduce the charge current on the cap.

I don't just throw these things together, you know.

Each post is a carefully crufted masterpiece that I spend literally seconds on.

Pah.

I doubt it with a MOSFET. They tend to 'trigger' over a very small voltage range. With a transistor, probably.

I want a smooth gentle fade in and out.

Hence the voltage divider in the circuit.

I did a bread board of the circuit and can assure you it doesn't fade in noticeably. It does fade out, though.