Mk2 Chopper Posted October 6, 2019 Report Share Posted October 6, 2019 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 Quote Link to post Share on other sites
Lebro Posted October 6, 2019 Report Share Posted October 6, 2019 (edited) 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 October 6, 2019 by Lebro Quote Link to post Share on other sites
RogerH Posted October 6, 2019 Report Share Posted October 6, 2019 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 Quote Link to post Share on other sites
Mk2 Chopper Posted October 6, 2019 Author Report Share Posted October 6, 2019 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 Quote Link to post Share on other sites
RogerH Posted October 6, 2019 Report Share Posted October 6, 2019 Hi Gareth, see attached for my simple circuit roger TR4A lights alarm.docx Quote Link to post Share on other sites
Mk2 Chopper Posted October 6, 2019 Author Report Share Posted October 6, 2019 That's really great, thanks Roger Gareth Quote Link to post Share on other sites
foster461 Posted October 6, 2019 Report Share Posted October 6, 2019 Roger, your circuit only works if the ignition is on, what am I missing ? Quote Link to post Share on other sites
RogerH Posted October 6, 2019 Report Share Posted October 6, 2019 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 Quote Link to post Share on other sites
foster461 Posted October 6, 2019 Report Share Posted October 6, 2019 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. Quote Link to post Share on other sites
RobH Posted October 6, 2019 Report Share Posted October 6, 2019 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. Quote Link to post Share on other sites
RogerH Posted October 6, 2019 Report Share Posted October 6, 2019 ah! yes. But then you get a faint buzz in the background The moral is - don;t sit in the car with the lights on and the Ign off. Roger Quote Link to post Share on other sites
RobH Posted October 6, 2019 Report Share Posted October 6, 2019 Fair point Roger, but your relay in the feed should eliminate the faint noise which Gareth says only occurs with the engine on. Quote Link to post Share on other sites
RogerH Posted October 6, 2019 Report Share Posted October 6, 2019 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. Quote Link to post Share on other sites
Lebro Posted October 6, 2019 Report Share Posted October 6, 2019 Is this a 5 minute argument or the full half hour ? Quote Link to post Share on other sites
RobH Posted October 6, 2019 Report Share Posted October 6, 2019 He hasn't paid so I'm not allowed to argue any more. Quote Link to post Share on other sites
mike3md Posted October 6, 2019 Report Share Posted October 6, 2019 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 Quote Link to post Share on other sites
Mk2 Chopper Posted October 6, 2019 Author Report Share Posted October 6, 2019 (edited) I'm glad this subject has caused some healthy argument discussion . 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 October 6, 2019 by Mk2 Chopper Quote Link to post Share on other sites
Z320 Posted October 6, 2019 Report Share Posted October 6, 2019 (edited) 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). 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 October 6, 2019 by Z320 Quote Link to post Share on other sites
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