DIY 'lights ON' warning buzzer circuit for classic Beetle???

[reubin78]

Quickly Googled this and found three ready made solutions.

I'm liking Solution 1 - what do you guys think?? Buzzer will only sound when ignition is OFF, BUT is it a good idea to have the relay permanently live while the ignition is on? Will it not burn out???


Solution 1
When the ignition is on the relay holds two contacts apart. When the
ignition is switched off the contacts close and connect the buzzer to the light circuit. If the lights are on then the buzzer sounds.

http://www.gbnetwork.co.uk/circuits/carlights/car_light_reminder.html

Solutions 2&3
These two headlight reminder circuits are easy to install and operate on the KISS (Keep It Simple Stupid) principle. The simple circuit involves adding just a 12V piezo buzzer between the lights circuit and a door switch. The buzzer sounds if the lights are left on and you open a door. The disadvantage of this simple circuit is that it's annoying to have the buzzer sound continuously if you want to leave the door open while the lights are on. The improved circuit
overcomes that problem by adding a 1000μF capacitor and a parallel 100kO resistor in series with the buzzer. Now, when a door is opened, the buzzer gives a brief burst of sound only, while the 1000μF capacitor charges. The 100kO resistor discharges the capacitor when the lights are switched off.

http://www.circuit-finder.com/categories/automotive/automotive-light/693/simple-headlight-reminders

 

[TicklyT]

Many automotive relays are permanently energised when the ignition is turned on - that's what they are built to do.

 

[reubin78]

Cheers TicklyT. I assumed that but nice to get the second opinion

 

[Mickymoody]

It's the classic build for any electronics student to build. Maplin sell them as kits, for £2.99 or so?

I'd have thought a classic Beetle owner, would know by now, to turn their lights off?

 

[reubin78]

I'm too busy trying to stop my chrome rusting to remember to switch off my lights - lol!!!

 

[Mickymoody]

I'm too busy trying to stop my chrome rusting to remember to switch off my lights - lol!!!

Plenty of vaseline! Might not look pretty, but should protect over winter?

Depending how much you love the car, might be an idea to invest in those horrible North American rubber bumbers for use in winter, then refit the chrome ones in spring?

I know people have created a car bra, to prevent stone chips, by wrapping the front of the car in clingfilm...bit too banal?

 

[reubin78]

Had a look on the Maplin website and struggling to find the kit

Any hints on what to search for???

 

[ajrobb]

On my old Maxi, I wired the fly leads of a buzzer (with built-in diode) between the headlight switch and the instrument panel supply. With ignition turned off, the thermo-mechanical regulator closed and the buzzer circuit completed (through the fuel gauge sensor I think). I mention the regulator because the buzzer would sometimes hesitate initially even coming on, going off and coming on again. It was quite sweet, almost like an apology for bothering you.

It was something like (I can't tell if this has a diode though):
http://www.maplin.co.uk/Module.aspx?ModuleNo=3213#spec

No other components or wires required.

 

[Mickymoody]

Had a look on the Maplin website and struggling to find the kit

Any hints on what to search for???

I've visited the Maplin shops on a regular basis, they have electrical kits on a rack, can't understand why you can't find anything on their website? Maybe they don't sell them on a website, as it could be construed as constructing something less savoury, if bought from abroad?

The circuit should be committed to memory, as it is a college experiment to build one, to demonstate making one, how good the soldering is, etc, so surprised to see that you can't find the info!

A quick maplin light buzzer kit, reveals this..http://www.maplin.co.uk/LIGHT_BUZZER_KIT.search that took 3 seconds, so unsure how you search for info?

 

[gblades]

Glad you found my website useful (1st link)

Maplin dont appear to sell the kit any more. The first item in the link the previous poster provided is designed to add an automatic setting to your car lights which is a different thing.

I would advise using the particular buzzer in the diagram. It is rated at 75dB @ 30cm which is a good volume and close to the volume of cars with the factory fit option. Fit it somewhere using a double sided sticky pad to insulate it from the vibration it causes.
Most other buzzers are a lot louder and higher in pitch. More like someone shouting at you in a high pitched voice that you have left your lights on than a gentle reminder.

 

[reubin78]

gblade,

Previously, checked out your parts list of Maplin. Seems that the relays have been discontinued. Any heads up on an alternative?

PS, website very useful - thought it only fair to reference it via a link

 

[gblades]

The buzzer draws about 25mA so current consumption is not an issue.
So all you need is a 12V relay with SPDT (single pole double throw) or DPDT (double pole version so half is unused).

http://www.maplin.co.uk/Module.aspx?ModuleNo=37494&OrderCode=N04AW would be suitable. You would need to solder the wires onto the relay pins. Alternativly something like http://cgi.ebay.co.uk/CAR-BIKE-12V-30-40-AMP-5-PIN-CHANGEOVER-RELAY-SWITCH-/400159618544 may be more easily mounted and easier to connect the wires to.

 

[reubin78]

Gblade,

I've finally had 5 mins to look through my box of electrical bits and I have a 4-pin relay (pins 30-85-86-87) which I am sure is usually used for the heated rear screen - is that of any use to this circuit?

If not I'll order the necessary.

Cheers for your help

 

[gblades]

No if its 4 pin then it will only be a NO contact which is only made when power is applied. You need a NC contact so power is applied to the buzzer when the ignition is off.

 

[TicklyT]

Have you considered just connecting a small electronic buzzer between the headlight supply, via a rectifier and t'other side to the courtesy light switch?

The courtesy light switch provides an earth connection only when the door is open. The rectifier protects the sounder against reverse polarity when the headlights are off (so the lead appears to be grounded via the headlamp filaments) and the door is closed (so the 'ground' side appears to be positive via the courtesy light filament)