49 replies to this topic

[fishturner]

Very helpful conversation!! keep it up guys

[Min E]

I just had an epiphany!

Ethel's right, but I didn't understand her/his (profile says male) explanation until now. When the door is closed and the buzzer is connected, the interior light circuit, instead of not earthing like it should be, will instead attempt to earth backwards through the buzzer and through the gauge light circuit!

There won't be enough current to light any of the lights, but it would drain the battery slowly.

I think I'll start looking for a suitable diode. I'm sure I have one around here somewhere. I think it would do best between the buzzer and the door switch wire, so current can't flow backward through the buzzer from the interior light circuit.

I can see exactly what you are saying and had already considered it, but I felt, possibly wrongly, that the directional properties of the buzzer unit acted in a similar way to a diode anyway, if it had been something like a relay coil or another bulb then there would definately be a problem.

What I am finding strange is that members who have already fitted this are experiencing different results, some say it drains others say they have no problem. Maybe different makes or types of buzzer have different properties.

If there were current drain then I would have thought it would be a fraction of what is used by having a clock in your car and probably even less than the radio uses to retain its tuning memory and I expect most of us have got one or both of those.

In post #28 above (p2) I showed the utilisation of a diode to resolve any possible problems.

If you want it to be perfect then the only way to totaly prevent any interference would be to fit a separate door switch just for the buzzer which is not a difficult nor an expensive job.

This one's £1.29 from maplin. (AY07H)



Drill a hole, job done. As a bonus it would only buzz when the drivers door is opened rather than either door.

Edited by MINY, 22 November 2009 - 11:33 AM.

[jmetal88]

I just had an epiphany!

Ethel's right, but I didn't understand her/his (profile says male) explanation until now. When the door is closed and the buzzer is connected, the interior light circuit, instead of not earthing like it should be, will instead attempt to earth backwards through the buzzer and through the gauge light circuit!

There won't be enough current to light any of the lights, but it would drain the battery slowly.

I think I'll start looking for a suitable diode. I'm sure I have one around here somewhere. I think it would do best between the buzzer and the door switch wire, so current can't flow backward through the buzzer from the interior light circuit.

I can see exactly what you are saying and had already considered it, but I felt, possibly wrongly, that the directional properties of the buzzer unit acted in a similar way to a diode anyway, if it had been something like a relay coil or another bulb then there would definately be a problem.

What I am finding strange is that members who have already fitted this are experiencing different results, some say it drains others say they have no problem. Maybe different makes or types of buzzer have different properties.

If there were current drain then I would have thought it would be a fraction of what is used by having a clock in your car and probably even less than the radio uses to retain its tuning memory and I expect most of us have got one or both of those.

In post #28 above (p2) I showed the utilisation of a diode to resolve any possible problems.

If you want it to be perfect then the only way to totaly prevent any interference would be to fit a separate door switch just for the buzzer which is not a difficult nor an expensive job.

This one's £1.29 from maplin. (AY07H)



Drill a hole, job done. As a bonus it would only buzz when the drivers door is opened rather than either door.

Well the thing that gave me a clue was, for some reason when the door was closed and I messed with the headlight switch I could hear static-like noises coming from the buzzer. It just took me until later in the evening to figure out it was probably being grounded through backwards that was causing the noise.

EDIT: And I forgot to mention as well, the buzzer did stop making those noises after I installed the diode.

Edited by jmetal88, 22 November 2009 - 03:55 PM.

[Min E]

All of this proves is that there is no substitute for experience.

This whole forum revolves around the people who have 'been there and done that'.

When I started this thread I had an idea, that idea was kicked around and now it's been tried, tested, adapted and tested again.

Thanks to those who have taken the time and trouble to input into this idea it works; but most importantly ....it works properly, and safely.


So...the final design for a "Lights On Reminder" is.....

A 12v buzzer (FK82D from Maplin) £1.99



A 1N4007 Diode (N78CA from Maplin) 18p



Then fit them like this :



If you want a 'special' job you could fit a separate switch into the door frame and take the black wire from the buzzer straight to it, no need for a diode and the buzzer will then only sound if the drivers door is opened.

AY07H from Maplin £1.29:

Edited by MINY, 22 November 2009 - 07:06 PM.

[Pooky]

What ends will be on the diode? How's best to connect it up? Soldered to a crimp?

[Min E]

The diode has a stiff wire from each end, they can be cut down but don't make them too short because the soldering could overheat the component and damage it. Keep it to at least 3/4".

Soldering is better than crimping but do not use too powerful a soldering iron; 15watts is ideal, 25watts max. Do not use one of the 'Weller' type 'instant heat' soldering guns nor obviously a blowlamp.

Always, insulate all joints, tape works but can eventually lose its 'stickyness' and come unwrapped, especially in the damp condition that is the interior of a Mini.

I always use 'shrink tubing', it's a PVC based tube which shrinks in diameter when you heat it gently with a match. It also adds mechanical strength to the joint. Don't try to put it on too soon after soldering as the residual heat will shrink it as you are trying to slide it on. Oh, and don't hold the match near it for long as it will burn.

Its available from Maplin either in individual pieces or an assorted box for £3.49 (NO3FT) which I personally recommend; there's a fair chance that you'll use quite a lot if it when working on a Mini:



I recently bought a similar box from Aldi

To be aboslutely sure of full insulation I would recommend that you use a piece of tube over the joints at both sides of the diode and then shrink another long tube over the whole assembly:

Edited by MINY, 22 November 2009 - 07:53 PM.

[ste88]

i know this is an old thread but i added a buzzer and used a scotchlock to the red wire from the headlight switch (the one that is 12v for the speedo backlights) and used the door switch one for ground. Will it be ok? thanks

[Ethel]

Quite likely it will,

From a little experiment of my own it looks like I might've been wrong in practice even if right in theory. I've found a buzzer that has current blocking polarity (acts like a diode) so they may be fairly common. Alas, I found it amongst some junk so can't say where to get one but it's nothing special.

[lawrence]

im glad this thread is back i think im going to do this a little later and probably follow the lighting up switches thread. Thanks min E and everyone else for this
L

[djshongo]

super-helpful thread - thanks!!

[beardylondon]

Holy thread resurrection, is there any update on this, or is the above still the best way to get a warning buzzer?

[KTS]

if you don't mind paying a little extra for a packaged solution :

 

https://www.12voltpl...zzer-72-db.html

 

you'd still need to include a diode in the line to the drivers door switch to avoid the buzzer going off when the passenger door is opened

 

 

[beardylondon]

Thanks, and which diode, as all the maplin links are dead!

[KTS]

the 1N4007 referenced above is rated for 1amp which should be fine for a buzzer, but a higher current rating would give some leeway if you want to add anything else into that earth line (e.g additional courtesy lighting).  adding a diode protected earth link to the passenger door switch as well gives the option of independent courtesy lighting on both doors

 

googling 50v 5amp axial rectifier diode will produce plenty of results, such as this (minimum order is 10 on that site).  

 

https://www.rapidonl...-5a-50v-50-0388

Edited by KTS, 18 June 2020 - 05:16 PM.

[Spider]

Sadly, Maplins who had been around a very long time, close a few years back.

 

CBS have these Buzzers, that come with Diodes;-

 

https://www.carbuild...zer-with-diodes

 

I use these in tandem on my Oil Pressure light and found them very good, but be warned they are on the loud side, though, can be toned down with a couple of wraps of rubber tape.

While looking for that, I see they now also have these;-

 

https://www.carbuild...-warning-buzzer

 

Which look a similar Buzzer to that KTS linked up from 12 V Plant. Handy to have options !

 

 

When I've fitted up Headlight Warning Buzzers, rather than wire them back to the Door Switch, I've connected them up, via a Diode, to the White Ignition Wire, so the buzzer sounds with the Headlights on and the Ignition off, but the door switch is an interesting option, not one I'd considered.