240v light fitting on 12v circuit with 12v bulb

[Boat_Around_Si]

Hey Folks, 

 

I hope you are all well at this time! 

So I've fitted a standard light fitting to with a 12v bulb to my boat. 

Getting a bit of a buzz through the radio.. 

 

Do I need to ground the yellow/green to the negative? 

The negative block is assumable grounded to the Hull. 

 

It's currently just got the blue to negative/black and brown to positive/red but I've not put the yellow/green ground wire anywhere... 

I just want to check it's not making some sort of dodgy ground loop affecting the Hull or something 

 

Your thoughts much appreciated - thanks 

[ditchcrawler]

You say bulb, is it an LED?

[Boat_Around_Si]

Yes is it a LED 

6w Bonlux Edison AC/DC 12/24v A60 LED

The light works great, low power use and very bright. 

Just strange noise through radio/aux connection makes me think maybe it needs grounding - the yellow/green wire is currently not connect to anything 

 

 

Edited May 2, 2020 by Boat_Around_Si

[nicknorman]

No the earth wire won’t help, and best to leave it disconnected in case it makes a circuit via the hull.

 

The problem is that the LED bulb has a switching regulator inside it, that creates some high frequency interference. Some makes are worse than others. There are two main sources of the interference, it radiating from the bulb itself, and also it travelling along the wires and radiating from them. Not much you can do about the first one except get a different make of bulb, but you might find a small (eg 0.1uF) capacitor across the wires near the bulb (or even on the back of the bulb holder) helps the second one. Also you can get a clip-on ferrite bead to pass the wires through, again located near the bulb, which acts to stop the interference passing along the wire.

 

This type of interference can be pretty difficult to eliminate and probably the best answer is to get a make of bulb that is less prone to emitting interference.

[TheBiscuits]

1 hour ago, nicknorman said:

This type of interference can be pretty difficult to eliminate and probably the best answer is to get a make of bulb that is less prone to emitting interference.

 

I think that should have been your opening paragraph Nick, with the explanation afterwards!

 

Tl:dr

 

Badly designed electronics are crap.  Use better ones, that may only cost pence more if anything.  The catch is that you don't know which one you have bought until it arrives!

[Boaty Jo]

Try bedazzled or the fitout pontoon

 

They are (or used to be) boaty suppliers I think.

[OldGoat]

Part of the problem is that folks use 'standard' radios which are designed for reasonable signal strength areas and which have no aerial sockets. Thus the interference signal from the light / why:  swamps the radio signal...

[ditchcrawler]

16 minutes ago, OldGoat said:

Part of the problem is that folks use 'standard' radios which are designed for reasonable signal strength areas and which have no aerial sockets. Thus the interference signal from the light / why:  swamps the radio signal...

Correct a good aerial outside the boat would probably sort it all out

[Bod]

4 hours ago, Boaty Jo said:

Try bedazzled or the fitout pontoon

 

They are (or used to be) boaty suppliers I think.

Exactly what we had to do.  Returned the offending bulb to the supplier, who wasn't surprised.  New supplied by Bedazzled(who also do various adapters for different bulb bases).

 

Bod.

[Boat_Around_Si]

Thanks everyone! 

 

So I've got a Sony car radio installed and its the aux feed from the TV to the radio where I noticed the buzz, sometimes it takes 15mins for buzz to start which is strange.

It actually looks like a good quality LED bulb and I have had others from that make that I've been impressed with - but I will contact them and look at the names you've suggested. 

 

Thanks! 

[Jen-in-Wellies]

1 hour ago, Boat_Around_Si said:

Thanks everyone! 

 

So I've got a Sony car radio installed and its the aux feed from the TV to the radio where I noticed the buzz, sometimes it takes 15mins for buzz to start which is strange.

It actually looks like a good quality LED bulb and I have had others from that make that I've been impressed with - but I will contact them and look at the names you've suggested. 

 

Thanks! 

If the buzz doesn't happen with the LED off <pedant>Please don't call it a bulb. It isn't a bulb!</pedant>, then it is the LED that is causing it. Another cause of buzz can be a ground loop when connecting an aux lead between two pieces of equipment. I've had that between a computer and a 12V amplifier, which is a similar case to your TV to car radio example. Got round by placing a ground loop isolator in between.

 

Jen

[bizzard]

There might be a bumble bee trapped inside the set and as it warms up it becomes active, hence the 15 minute delay.

Edited May 3, 2020 by bizzard

[nbfiresprite]

11 hours ago, bizzard said:

There might be a bumble bee trapped inside the set and as it warms up it becomes active, hence the 15 minute delay.

Which is why the only music  and news that Bizzard can get from his radio, is all about honey.

[Boat_Around_Si]

Thanks so much for your replies!

 

I found the bee and squashed it - with a ground loop noise isolator - thanks Jen_in_Wellies for the suggestion.

I was worried something was happening to the electrical grounding on the bot, but now I feel better!

 

Have a great week everyone ??