Wiring up a headlight warning device

[DANNY8]

Wiring up a headlight warning device.

To start with, have a look at the attached image.

I was thinkin this could (when hooked up to a buzzer or sumfin) go off when the ignition was turned off when the headlights are left on. The warning device gets its power from a relay which is switched on when the headlights are on, and it earths out from a relay which gets switched when the ignition is off. The problem I have is getting power from the ignition when it is off, so it switches the relay on.

Anyone know a way it can be done?

I was also thinkin, if I change the diagram so it's wired up to the 'on' position on the ignition, and when it's switched on, the relay is switched on, and the input side of the relay I will have nothing connected (as I'm making it complete the earth circuit, having nothing connected will mean it isn't completed), so when it's switched off I was thinkin the output could earth through the relay...if ya know what I mean?? But I dunno how the relay actually works so not sure if that idea will work.

Does anyone actually understand what I'm trying to say? lol It's hard to explain :P

[kopper69]

Your best option for a headlight reminder might be a tried and tested option. Both dick smith and jaycar sell kits that you simply solder up and wire into the car.

Dick smiths code is L5461 - It looks like they are discontinuing this though so not every store has them

Jaycars code is KC5317

These items just alarm if you leave your headlights on, but you could easily change them to turn your lights off if that is what you want.

Its probably a cheaper option than trying to run relays, the price of one relay is probably close to the cost of the circuits above

[Cheap6]

Understand? Not really.

Is there a reason you don't want use a commercially available unit? ($$$ or the challenge of figuring it out yourself I would consider as valid.)

eg.:

Jaycar Electronics

Silicon Chip Online - Headlight Reminder For Cars

Headlight Reminder Kit [K4348] - $19.95 : Zen Cart!, The Art of E-commerce

The ones I have seen work using a comparator circuit ( Comparator - Wikipedia, the free encyclopedia ) wired across the headlight and ignition relay outputs. They also have a timing device to switch of the alarm after a period of time with the ignition off.

[PanthaVS]

agreed with above...

but if you insist on making it, (for the pride of knowing you made it)

i can design a circuit for you, just need to know what conditions it's based on?

do you want it just a buzzer? do you want headlights to turn off when you open a car door? etc....

[PRH]

well i think you could put a buzzer with the positve to the headlight feed and earth it through the ign,you would need a diode in circuit to stop it backfeeding from the ign to the headlights.
It works because when ya have the engine running with the headlights turned on there isnt anywhere for the buzzer to get an earth,when ya turn off the ign the buzzer gets an earth through the ign circuit.
Phillip

[maginoodle]

an easier way is to put a relay on the lighting circuit that cuts power to the lights when the ignition is off.

[kopper69]

an easier way is to put a relay on the lighting circuit that cuts power to the lights when the ignition is off.

Actually you could put the relay on the ACC circuit, which comes on when the key is turned to ACC or ON and use that to disconnect the lighting circuit. That relay is still going to cost $15 or so. You wouldnt be able to turn the lights on unless the ACC was in, but you could put an override switch in to all you to turn the lights on anytime.

If you do go with a relay option, let us know so we can advise of the correct relay (there are a few different configurations)

[maginoodle]

the reason i said relay is so you dont have to worry about the lights. i hate buzzers and warning sounds for things like lights, seatbelts(although i now automatically put my belt on).

[VrWagz1]

This might work, i cant see why it shouldnt if you want to use relays. you need 1 N/O realy and 1 N/C relay and the ability to translate crappy paint drawings

[kopper69]

the reason i said relay is so you dont have to worry about the lights. i hate buzzers and warning sounds for things like lights, seatbelts(although i now automatically put my belt on).

The advantage of a buzzer is that you still have full control over the lights. If you use a relay, the lights will turn off as soon as you open the car door if the car is off (unless you get a little more complex with the wiring). In the later models you simply switch the control switch off then back on and you can still turn the lights on, so you have complete control. With a buzzer, its there as a reminder. If you choose to have your lights on while doing something you just ignore the buzzer. If you forget to turn the lights off you will be reminded.

VrWagz1, there are relays out there with a N.C and N.O contact so that you dont need 2 relays. Actually your circuit has a few flaws.

- Each headlight has a seperate power to it, but a common ground at the switch. To control both lights easily you would need to interrupt the ground from the switch, so your first relay wouldnt work. Your second relay is wired incorrectly. If it was a N.C relay, it would open when the ignition was on and the lights wouldnt turn on when the car was running!

[VrWagz1]

The advantage of a buzzer is that you still have full control over the lights. If you use a relay, the lights will turn off as soon as you open the car door if the car is off (unless you get a little more complex with the wiring). In the later models you simply switch the control switch off then back on and you can still turn the lights on, so you have complete control. With a buzzer, its there as a reminder. If you choose to have your lights on while doing something you just ignore the buzzer. If you forget to turn the lights off you will be reminded.

VrWagz1, there are relays out there with a N.C and N.O contact so that you dont need 2 relays. Actually your circuit has a few flaws.

- Each headlight has a seperate power to it, but a common ground at the switch. To control both lights easily you would need to interrupt the ground from the switch, so your first relay wouldnt work. Your second relay is wired incorrectly. If it was a N.C relay, it would open when the ignition was on and the lights wouldnt turn on when the car was running!

Yes granted if that is the case, and the lights circuit is alway live and simply grounded after the swithch, then you will need to pick up that parker feed after the switch then, but the idea is for the n/c relay is to open when the lights are on so it will cut the power going through the contacts to the buzzer supply, otherwise the buzzer would never stop. by your wording it sounds like you are thinking the lights are running through the contacts on these relays. That is not the case, the existing lights circuit stays as is, this circuit is to be built over top of the existing circuits and only "teeing" power off them at certain points. And a relay with n/o and n/c contacts will not work, because it does not have 2 individualy run coils in it. The circuit relys on them being able to be operated individually. Hope that makes sense

[kopper69]

My mistake, I thought your circuit was to control the lights, instead it is only to control a buzzer. The only problems than are:

2 relays cost more than the commercial circuits above and
Mechanical relays are less reliable than solid state components used in the circuits above, and as you are only running a buzzer solid state components will provide more than enough power. The relays can supply 10+ amps each, but you are only using, say, 0.1A for the buzzer.

[VrWagz1]

My mistake, I thought your circuit was to control the lights, instead it is only to control a buzzer. The only problems than are:

2 relays cost more than the commercial circuits above and
Mechanical relays are less reliable than solid state components used in the circuits above, and as you are only running a buzzer solid state components will provide more than enough power. The relays can supply 10+ amps each, but you are only using, say, 0.1A for the buzzer.

Your right there, but as the original question, its just a simple method to do it if old mate wanted to use relays like he asked. Just needs to change the bit where you pick up the power from the lights to be after the switch not before.

[DANNY8]

Thx heaps for the feedback guys. I think I might just chuck a relay in the lights so they turn off with the ignition. My Mum's Pajero is like that and I like it. Cheers.

[krypt0n]

There's another way to do it also.

If you get a small buzzer (make sure it's 12 volts and polarised (ie it has a positive and negative lead)) and go to the fuse panel, get the positive lead from the buzzer and put it in with the fuse for the headlights, and the negative lead goes on the radio fuse.

The way this works is when your headlights are ON and the car is RUNNING, there will be +12v on that fuse, and the radio fuse will have +12v - this causes a voltage difference of 0v which basically means the buzzer won't sound.

However, when the car is NOT RUNNING, the radio fuse has 0v and if the headlights are ON the headlights fuse will have +12v, creating the 12 volts to run the buzzer.

If that doesn't work, check the polarity and voltage of the buzzer, and double check where you've connected the wires into the fuses.

Cheers,
Dave

[kopper69]

Thats a good idea krypt0n. Have you tried it out? It sounds good in theory, as long as the buzzer didnt mind the reverse polarity when the car was on but lights were off. Might need a diode in there if the buzzer didnt like that.

[Reaper]

I have two bright lights that are at the front of the car to remind me that I have left my headlights on. Most cars have them factory fitted.

Reaper

[krypt0n]

Thats a good idea krypt0n. Have you tried it out? It sounds good in theory, as long as the buzzer didnt mind the reverse polarity when the car was on but lights were off. Might need a diode in there if the buzzer didnt like that.

Yep, it works in my S1 VN with no problems. No need for a diode, but you can add one in if you're concerned about it. Most you'd pay would only be a few dollars for a buzzer, but mine has been going strong now for about a year

[kopper69]

Well done mate . Always like to hear the simple (but clever) ways that work.

[krypt0n]

I have two bright lights that are at the front of the car to remind me that I have left my headlights on. Most cars have them factory fitted.

Reaper

I know that I will most likely never see it for myself, but just knowing that one day you will forget to turn your lights off and flatten your battery, is prize enough.

Karma - 'nuff said

[VrWagz1]

Good thinkin krypton, thats the simplest best idea yet.

[Dads VP Nitron]

an easier way is to put a relay on the lighting circuit that cuts power to the lights when the ignition is off.

This is a simple solution to preventing flat batteries due to leaving you lights on but if you stuff up and a wire comes loose in one of the relay terminals or your relay becomes faulty your headlights might stop working while you are driving! I'm going to use a buzzer instead.