I'll toy with it in the coming days, just to confirm if what I described is actually feasible, or find out if I'm wrong. I'll chime in on here with the result, and if it works I'll take a video and/or explain how to do it exactly.

 

Yes - well I understand that one can have a circuit like this connected to + and - 12V and using the glovebox or door switch as trigger. The lack of trigger (using power application as trigger) was to simplify it. IF using a switch as separate trigger the requirement is that even if the trigger is stuck on triggering, the circuit should still cut the power after n minutes. I bought a timer off Ebay a while ago that had a trigger button but if one held the button pressed the circuit woudl never switch off the power, so that timer was useless to me - defeating the entire purpose.

I am hoping that this thing I bought off Ebay will work and I'll be able to even take the relay off and just have a transistor drive the small LED, in order to have the least power drawn, considering I am switching very small currents. But I have to wait for quite a while, I think approx arrival time is April! Bah...no problem, no urgency I guess.

I also bought a resin potted module off US which has both the delay on closing the door (with fading) and timeout on 10 mins - it was expensive though, around $33AUD from Ebay - they wanted almost $50 in fact - whoa. I will not be able to reverse engineer that one as it is potted but I need several of these for several cars, so one will get this all in one solution.

 

Yeah I mean if you're looking for simplicity of not having a trigger, I'm not sure what you can use to accomplish that, but I imagine it would have to involve a tiny micro-controller and small circuit board so you can program the IC to do what you're looking to do. But simply taking the wire from the switch to that will be going to the common input, and jumping that same wire over to the + trigger of the coil, is pretty darn simple for sure. Just a small jumper wire is all you'd need, there's nothing to it. And there wouldn't be a chance of the light being left on beyond 10 minutes in the scenario I described, regardless of the switch being open or closed. If the glove box door is opened, the switch will trigger the relay to turn on and start counting down the timer immediately. If the glove box stays open, the timer disconnects power to the switch after the 10 minutes. If the glove box is manually closed within the 10 minute count-down, the relay loses power through common from the switch, removing power from the light bulb. Unless I'm misunderstanding something, that should be fail-proof.

Btw, that potted unit you bought in the second link is shipping from just a few hours away from me haha. Why not de-pot it?

 

Arrived yesterday, fitted today. It is TINY. It took an hour to fit, not easy like they say,, considering also the stack of money I paid for it.

I had to change the wiring of the dome lamp and cut wires - not funny for a car undeer warranty but those have this already I guess. You need to solder or use crimps and crimp splices (I did not solder, for once, I know it is bad - oh well).

The original wiring was bringing +12V continuous, -12V continuous (ground) and -12V trigger from doors. The bulb inside the dome light is connected to +12V permanently and a slide switch connects to continuous -12V or door -12V (or nothing). This circuit feeds +12V to the bulb, so -12V must be continuous. So I had to change the wires around at the dome light entry and splice +12V, -12V and cut the door -12V and feed it to the light delay circuit. Bah... I did not use the ignition wire (so the light dims immediately upon closing the door, I don't see the use of that, it dims anyway after only 20 secs)

Oh, and also before dimming there is a jolt in the voltage , not nice to the eye. Also none of the times - dim and timeout, are adjustable. Waaay overpriced. If it dies, it goes to bin, cannot repair it.

Whatever... I fitted it regardless.

I have another 3 places at least where I could use a timeout (2 gloveboxes and a boot light), so I am still waiting for the China stuff. Just a heads up that the 'easy to fit' circuit is not that easy to fit at all.

EDIT: the circuit screwed up my headlight reminder by sending a + along the door control wire (ground from the doors) and making the reminder beep when light were on regardless of ignition and door. Thankfully adding a diode on the ground from doors stopped it. While I did this I also ran a wire from ignition to the circuit - yesterday i drove that truck and it was VERY annoying starting to drive with the light on... ignition wire makes it dim immediately on door close. Being a 1991 Nissan Patrol, drawing the wire along the pillar was a little nightmare (as vehicles were made properly then with lots of metal)... etc etc

 

Here's my second version modified to use the discharge time cycle. Q1 acts as the trigger when power is first applied to charge electrolytic capacitor C2. Q1 shuts off when C1 is fully charged. Time delay about 10.5 minutes with the components shown.
SG

 

@sghioto
How did you calculated the time constant that the "Time delay about 10.5 minutes" ?

 

@sghioto
How did you calculated the time constant that the "Time delay about 10.5 minutes" ?

I didn't calculate it, I measured it. The answer is similar to my post #17 except now the cap is discharging. Let me be clear when I say "time delay" it means when the relay drops out.
SG

 

What if the power cuts off, immediately or with some delay - will the relay drop out immediately as well?

If you could devise a circuit that holds the relay for say 30 secs (10-50 e.g. adj via trimmer) on power off and also switches off the relay after the large delay (also adj via trimmer) if power is maintained, that would be the dream dome delay circuit (akin to what I spent a lot on)

(by 'power off' I mean (-) if that matters)

EDIT well of course it would also need the dimming function instead of abruptly switching off but that woudl be a simple thing (discharging via another capacitor)... and so, the circuit becomes more and more complex.

Anyway, for what it is, looks good!

 

What if the power cuts off, immediately or with some delay - will the relay drop out immediately as well?

If you could devise a circuit that holds the relay for say 30 secs (10-50 e.g. adj via trimmer) on power off and also switches off the relay after the large delay (also adj via trimmer) if power is maintained, that would be the dream dome delay circuit (akin to what I spent a lot on)

(by 'power off' I mean (-) if that matters)

EDIT well of course it would also need the dimming function instead of abruptly switching off but that woudl be a simple thing (discharging via another capacitor)... and so, the circuit becomes more and more complex.

Anyway, for what it is, looks good!

Well Thanks. Yes certainly becoming more complex! This new circuit would be used for a dome light? Doesn't the vehicle already have that feature? You don't need that for a glove box light correct?
EDIT: The answer is yes to your first question.
SG

 

Cut-off only for glovebox, the other features would be for a dome light - a usable circuit that costs way less than what I bought off EBay (see above)

 

Asked this in another thread but it was combined with another question and never got an answer...

I am looking for a VERY simple circuit to switch off an interior or glovebox light if the door has been left open (eg overnight) to prevent battery going flat, light burning out,. melting enclosure etc

There are gazillions of circuits on the web but all seem to use a trigger. I need one that does not need a trigger. Just connect 12V , output on instantly, then after 10 mins switch output off even if the input is still on. If input is off, of course, switch output off.

HI

I didn't read thru this entire thread but the attached should work for you.
Power needs to be supplied to the circuit when the door opened. This action causes the LED to light and starts the timer. If power is still on when the time completes, the LED will turn off. Time is approximate and is adjustable from 8-18 minutes. I used the NE555 because I felt it was more rugged then the CMOS version. The parts shouldn't be very expensive...less then $10 USD.

 

So let us knows how it worked.

Ok, received it and it works as required - nice! I'll get another 2 ...

Must use relay most likely because the LED lights do take more power than the relay coil and don't want to burn the electronics.

 

Great! Problem solved.
SG

 

Well - some very good circuits here - I'd be interested to find out what the China module uses... too late now , it is installed, but I bought another 3 and when they arrive I will look at the chip used.

Of course one cannot compete with prices from China - and of course they had no clue as to how to configure jumpers for various times, vendors usually sell 1,000 items and have no clue what they do or even what they are. Fortunately the jumper srtting was the same as for another kit I bought which required pushing a trigger but I'm quite sure it uses most of the same components and IC...

It is becoming a matter of knowledge on what to choose and how to program rather than design from scratch... But as China becomes richer and prices will increase, we may see a reversal of all this - we shall see!

EDIT: The relay was using 30mA, the test LED load - a moderate COB LED, was taking 300mA, hence keeping the relay... glovebox LED is smaller but why risk it, when it switches off the load is very close to zero (well by bench supply cannot measure it so around or less than 1mA).

 

I'd be interested to find out what the China module uses.

Surface mount pic chip. The number is usually not visible on the component. It's nothing fancy or new the details are in how it's programmed.
SG