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Lights left on warning buzzer

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I've recently fitted a cheap ebay (probably the answer right there) lights left on warning buzzer. 

This has a built in blocking of reverse polarity. I've wired it to the rear lights red wire and the door switch. When the lights are on and I open the door the buzzer sounds - great. 

But...when lights are off with door closed AND engine running, there is a feint whistling sound. 

So I'm thinking it's taking the 12v from the door switch and leaking to earth through the light circuit, the reverse polarity that it's supposed to not do. Occasionally it doesn't do it all. 

Just wondered if anyone has any thoughts about it, as the idea seems a good one if it works properly. 

This is on a TR6.

Cheers

Gareth

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Your first thought could be correct, although these buzzers generally don't work with reverse polarity anyway. Alternatively the wires connecting the buzzer to other circuits may be picking up the AC ripple on adjacent live circuits which are passing  current from the dynamo / alternator.

you could try wiring a resistor across the buzzer say 1K ohms ¼W or a small electrolytic capacitor.

Bob.

Edited by Lebro

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Hi Gareth,

are you handy with a soldering iron ?

If Bob's ideas do not do the job (I suspect they will) then consider making your own.

A SPST (single pole single toggle) relay  https://www.ebay.co.uk/sch/i.html?_odkw=12v+buzzer&_osacat=0&_from=R40&_trksid=p2045573.m570.l1313.TR1.TRC0.A0.H0.X12v+SPDT+relay.TRS0&_nkw=12v+SPDT+relay&_sacat=0

 

A buzzer    https://www.ebay.co.uk/sch/i.html?_from=R40&_trksid=p2380057.m570.l1313.TR3.TRC2.A0.H0.X12v+buzzer.TRS0&_nkw=12v+buzzer&_sacat=0

 

connect one end of the relay to the Ignition system (white wire)

Connect other end to earth

Connect one pole of the relay to the side lights

Connect other pole to the buzzer.

Connect other bizzer connector to earth

Stick it all in a little box

 

Roger

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Thanks Bob, I'll try your suggestion, thanks for that. ;)

Roger, yes I enjoy a bit of soldering, nice idea and would be fun to put together, I'll try Bob's first bit thanks for the suggestion. 

Gareth

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That's really great, thanks Roger 

Gareth

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Roger, your circuit only works if the ignition is on, what am I missing ?

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Hi Stan,

with the ignition on the relay flips over to power the Normally Open contacts = buzzer not on.

With side lights on and ignition off the side lights pass through the Normally Closed contacts to the buzzer = buzzer racket.

With both side lights and ignition off = nothing.

 

Roger

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7 minutes ago, RogerH said:

Hi Stan,

with the ignition on the relay flips over to power the Normally Open contacts = buzzer not on.

With side lights on and ignition off the side lights pass through the Normally Closed contacts to the buzzer = buzzer racket.

With both side lights and ignition off = nothing.

 

Roger

Got it. Clever.

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Gareth's original scheme had the buzzer on only if the door was opened. That way the buzzer isn't going all the time if you sit in the car with the lights on and ignition off. Connecting the earthy end of the buzzer to the door switch instead of straight to earth, as Gareth described, will remedy that.

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ah! yes. But then you get a faint buzz in the background:P

 

The moral is - don;t sit in the car with the lights on and the Ign off.

 

Roger

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Fair point Roger, but your relay in the feed should eliminate the faint noise which Gareth says only occurs with the engine on. 

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Hi Rob,

not really a fair point just simply arguing for the sake of it.

I knocked it up quite some years ago just in case I left the lights on. That column switch is so easy to knock getting out of the car.

I had considered fitting some sort of timer delay unit that would override the buzzer for 10 mins or so.

The TR4A does not have a door light switch.

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Is this a 5 minute argument or the full half hour ?  :ph34r:

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He hasn't paid so I'm not allowed to argue any more. -_-

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I have put something similar via an oil pressure switch on my 4 for oil pressure warning. It includes a very loud buzzer to get my attention when the roof is down and I am not checking the pressure gauge, and follows an incident a few years ago where I lost all pressure when the pump drive sheared at 60mph+ - by the time I noticed the gauge it was too late!

It goes live with the ignition, but to avoid frightening the neighbourhood incorporates a 10 second delay on start up (only).

May be able to find the details if anybody is interested.

Mike

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I'm glad this subject has caused some healthy argument discussion :P.

The relay for sure would eliminate the unwanted noise, but I've a feeling I still have some resisters that I wax using for an LED light chaser I put together. Will update when I've had a chance to try it. 

Gareth

Edited by Mk2 Chopper

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Hi,

I use the VW warning buzzer since 2014, this is relay #36 on every Volkswagen, 2 € from the scrap yard.

Terminal 58R or 58L connected to "light", terminal 85 to 12 V from ignition (is ground when ignition is off). 

P1210005-b.JPG.b25c55e2f855d829abc298f97ec8d72a.JPG P1210015-b.JPG.a980d571e3f2f6e479d2279a54a27ca6.JPG

For "light" I use dipped beam, so I can leave the car on the street with the position lights on (when its dark)

and with the key off to open the garage without the attention of my neighbors.

Ciao, Marco

Edited by Z320

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