Okay.
But I'm concerned about electrolytic capacitor leakage current being a problem at such low discharge currents.

That's true about all timing capacitors. I would use a tantalum cap.
EDIT: changing the resistor to 1M increased time to 9.5 minutes.
Changing relay to a 12 volt,12.5ma ( Digikey Z774-ND ) and keeping the resistor at 470K increased time to over 10 minutes.
SG

 

Hi folks, I'm a newbie here, but was looking to do something very similar for my vehicle last year and never got around to it, but perhaps this may be of help. I was looking to leave my headlights, reverse lights, and puddle lights on my SUV on for 60 seconds after turning off the ignition. I know you want to avoid a relay, but I was looking into one of these for my project:

https://www.12voltplanet.co.uk/adjustable-delay-timer-relay-delay-on-or-off-12v-10a.html

Seems relatively simply to use, and not much larger than a regular relay.


I also came across this, and for the price, I don't think you can beat it. Maybe just de-solder the piezzo buzzer:

https://www.ebay.com/itm/12V-Displa...-Delay-Switch-Module-Car-Buzzer-/322173021875


Both items seem to be capable of 10 minutes on the delay. Could you not just snip the wire to your dome light or glove box light circuit, run one end of that circuit to common and jumper it to the positive trigger, connect the opposite end of the circuit you sipped to the normally-closed (or perhaps normally-open???) terminal, and use a negative door pin circuit as a trigger for the coil? Bare with me, because my skills with electronics are pretty limited, but I would think laying it out this way would allow you to maintain functionality of the dome light or glove box circuit under normal conditions, but each time the door is opened it would trigger the time to start the 10-minute countdown, which will then open the circuit, this turning off your light until the next time it is powered on? Sorry if I'm way off, but maybe at least the above gives some ideas of what can be accomplished with either of those devices.

 

Hi, thanks for that but 35 pounds sterling for that relay?? Wow...
The EBay relay looks interesting if I only understood how it works from the Chinglish description lol...

 

That's true about all timing capacitors. I would use a tantalum cap.
EDIT: changing the resistor to 1M increased time to 9.5 minutes.
Changing relay to a 12 volt,12.5ma ( Digikey Z774-ND ) and keeping the resistor at 470K increased time to over 10 minutes.
SG

100uF tantalum is rather hard to find and expensive - at the electronics store here anyway? Max is 47uF which is $AUD2.30 or so already , ,would need 2 or 3 in parallel?

 

Two in parallel should do it. You don't have to use a tantalum type but would recommend, the circuit was working with a standard electrolytic.
SG

 

Yes I know but that's $4.50 just for the caps. Will try electrolytic of course - what is the problem with leakage - shorter delay time or unpredictable or both? Immediately or in time (ie after being in operation for a while)

 

what is the problem with leakage

The circuit may never time out.

 

The EBay relay looks interesting if I only understood how it works from the Chinglish description

This one's description seems to indicate it will do what you want.
But no guarantee.

 

From the description it should, unless space is an issue. You certainly cannot beat the price. Good find crutschow.
SG

 

Hi, thanks for that but 35 pounds sterling for that relay?? Wow...
The EBay relay looks interesting if I only understood how it works from the Chinglish description lol...

Yeah it's definitely pricey, but if it does work for what you need, it could save you a lot of time spent building something else. And the compact size is awesome. But yeah, definitely not inexpensive.

The eBay one seems nice because you know exactly how much time you have configured to the timer for, based on the display. No guessing. If you want exactly 10 minutes and 0 seconds, you can achieve that on the first try. For under $5 I don't think you can go wrong with ordering one and figuring it out. Surely you could find some other use for it if it didn't work out, or worst-case is you just wasted $5.00. Plus it is ePacket which doesn't take nearly as long as anything else coming from China.

You could also look at some of the other listings for the same product and see if someone else gives a better explanation of it. Might even be able to find some YouTube videos showing how it works or something.

 

Maybe you could try this -- 5 to 30 Minutes Timer Circuit using 7555 IC.
7555 datasheet.

 

Re the Ebay timers - I need one that does not have a trigger, i.e. you just connect the power and the output switches on then off after n minutes.

Sgioto, I could not find this in the description - those jumpers are to set the time but is there a trigger button? I got something similar a while ago and it had a trigger button. If you did not hit it it woudl never start timing. If you held it down it woudl never time out. Something like that is of no use of course...

I can ask the seller but from experience they have no idea what they are selling...

EDIT: I bought it anyway, see how it goes when i finally / if I get it

 

Confused about your "I need one that does not have a trigger, i.e. you just connect the power and the output switches on then off after n minutes" statement. Can you elaborate a little more on that? What action is required for the output to switch immediately on, then off after xx minutes? Something has to trigger something else to happen. Whether that trigger be a switch, a sensor, a connection....

Sorry if I misunderstand, but if you can explain that a little better maybe I can help with that part.

 

Connect power to the black box, output immediately switches on and then switches off after n minutes. Disconnect the power to the black box, output immediately disconnects. Trigger is connecting the power...Imagine leaving a door open on your car overnight and the dome light draining the battery. This black box will switch off the light after n minutes with no additional action.

 

Re the Ebay timers - I need one that does not have a trigger, i.e. you just connect the power and the output switches on then off after n minutes.
Sgioto, I could not find this in the description - those jumpers are to set the time but is there a trigger button? I got something similar a while ago and it had a trigger button. If you did not hit it it woudl never start timing. If you held it down it woudl never time out. Something like that is of no use of course...

I don't see any trigger input connection from the photo of the PC board and there is no mention of a trigger in the description.
SG

 

We shall see, I have bought it now

 

We shall see, I have bought it now

So let us knows how it worked.

 

This will be sometime in April considering the postage times to AU from China / HK

 

OK, not sure what this black box is you're referring to, but I'm thinking you meant glove box. If that's the case, why not do like I suggested and use the glove box circuit as the trigger? The glove box light is activated by a switch, and you can use that switch to activate the timer relay module you bought. When the switch is closed (glove box door is opened), the output of the switch can be used as the coil trigger for the relay. Whether you leave the glove box open at the point, or shut it, the timer relay will ensure the circuit to the glove box light returns to an open circuit after the specified time. Run the glove box switch output to both the common and the + trigger of the coil, and run glove box light bulb wire to the common.

You could also use a secondary relay wired to your ignition switch, and wire is so that when the key is not in the accessory position (this usually includes the "ignition" position), the secondary relay will trigger the coil of the timer relay to the glove box light. So any time the key is not in the ACC/ON position, the timer will have already started the 10-minute countdown. If the glove box is opened while the ignition is off, the relay would be re-triggered and the countdown would start over again.

I'm pretty sure you could accomplish this either way, but the latter being the slightly more complex way due to needing a second relay and needing to wire the relays together, to the ignition switch, and to the glove box switch a certain way. Surely possible though, just have to figure out what you want to do and I think one of us can help. I can test the method of using the glove box switch as the trigger perhaps this weekend if you would like, using an ATMega328, a momentary switch, a relay, and a breadboard. The micro-controller would be used start a timer once the circuit on the switch is closed, using the switch's output circuit both as a trigger and as the common. Just to make sure what I'm suggesting would even work. Let me know if that interests you.

 

Whoa - if you want to play with it fine, I'll just wait for the China-made module for now, maybe get the 7060 in the meantime as well although I am baffled by the C3 10uF capacitor which must be 'non-polarised' ... like what? Sounds like an expensive part again - seen something like a crossover cap but that's like $6-$7 alone. The whole China module is around $3.50 AUD - I know, we can;t compete, but for one part that seems a bit steep.