STRONG MAGNET/DASHBOARD

Discuss other problems here.
Forum rules
By using this site, you agree to our rules. Please see: Terms of Use
Post Reply
djk3816
Minor Friendly
Posts: 21
Joined: Thu Jun 20, 2019 12:37 pm
MMOC Member: Yes

STRONG MAGNET/DASHBOARD

Post by djk3816 »

Rather than using double-sided tape to affix things on the dashboard, I am thinking of using a magnet(s) . Neodymium magnets are VERY strong (for example 10mm x 1mm will support 2kilos) . Will such strong fields have an adverse effect on any equipment behind the dash. up to 600cm away ?
I think not, but wondered if anyone has a view/experience of this ???
User avatar
geoberni
Minor Legend
Posts: 3544
Joined: Fri Aug 04, 2017 11:19 am
Location: North Leicestershire
MMOC Member: Yes

Re: STRONG MAGNET/DASHBOARD

Post by geoberni »

Unlikely, as there's not a lot there. The speedo moving parts are not ferrous material as far as I know. I'd be more worried about what you might be holding up there.... :)
Basil the 1955 series II

Image
JOWETTJAVELIN
Minor Legend
Posts: 2775
Joined: Mon Dec 12, 2011 7:20 pm
Location: LANCASHIRE (paradise)
MMOC Member: Yes

Re: STRONG MAGNET/DASHBOARD

Post by JOWETTJAVELIN »

Wiper motor and petrol pump might be affected, same with the gauge. The only way is to put it to the test. There was a fault in a signal box once where a track circuit indicator permanently showed 'occupied', after much head-scratching and testing the cause was eventually traced to the fish tank on the block shelf!
philthehill
Minor Maniac
Posts: 10748
Joined: Thu Jul 19, 2012 12:05 pm
Location: Hampshire
MMOC Member: Yes

Re: STRONG MAGNET/DASHBOARD

Post by philthehill »

Makes a change from leaves on the line. :D

I would be interested to learn more of this fish tank interfering with line block instruments.

User avatar
geoberni
Minor Legend
Posts: 3544
Joined: Fri Aug 04, 2017 11:19 am
Location: North Leicestershire
MMOC Member: Yes

Re: STRONG MAGNET/DASHBOARD

Post by geoberni »

Everything is 'Relative'.
The magnetic field from such magnets, is strong, but the field strengthen diminishment is not linear.

I use such magnets a fair bit.
I can get this block of 20 2x8x25 placed on a smooth desktop surface, as close as 40mm before there is any sign of attraction between the magnets and my Leatherman.
20210126_122651.jpg
20210126_122651.jpg (496.44 KiB) Viewed 2374 times
20210126_122845.jpg
20210126_122845.jpg (577.02 KiB) Viewed 2374 times
If they connect it's a heck of a pull to separate them, but you'd need to be a real geek with some serious equipment to measure any field out at 600cm, that's 2ft!

Neodymium magnets are all over the place these days. An electric car can have a Kilo of them in it's motor.
philthehill wrote: Tue Jan 26, 2021 12:31 pm I would be interested to learn more of this fish tank interfering with line block instruments.
Making an educated guess, I would imagine it was the electric cable to the tank air pump, routed alongside the cables for the signalling system. The AC supply in the pump cable would generate an Electromagnetic Field (EMF) and induce a signal into the signalling wiring.

I've seen such things several times in my career. On a similar vein to false train signalling.....
When I was in the RAF at a Base in Germany in the late 70s, the Royal Signals who were responsible for maintaining the base telephone system were dumbfounded as to why the phone system suddenly developed a fault where British Forces Radio (BFBS) was faintly in the background of the entire station phone network. You could hear it over the Dial Tone.
The 'Powers that Be' never knew why it stopped doing it either.
What had happened was the Base had a piped radio station to all the barrack block rooms, like a sort of Hospital Radio Network, all run by volunteers as a Club.
Someone had decided it would be a good idea to have a phone extension in the Studio and over the weekend had run a phone cable to the studio, cable tying it to the main studio output to the Amplifiers. :roll:
During the day, when the volunteers were mainly at work, BFBS was switched on to go out over the network; the studio output cable EMF then induced the BFBS content onto the phone system :o
It was like it about a week if I recall, before one of the Club members realised what had happened...
Basil the 1955 series II

Image
philthehill
Minor Maniac
Posts: 10748
Joined: Thu Jul 19, 2012 12:05 pm
Location: Hampshire
MMOC Member: Yes

Re: STRONG MAGNET/DASHBOARD

Post by philthehill »


User avatar
geoberni
Minor Legend
Posts: 3544
Joined: Fri Aug 04, 2017 11:19 am
Location: North Leicestershire
MMOC Member: Yes

Re: STRONG MAGNET/DASHBOARD

Post by geoberni »

I saw that last year. Little titbits along the lines of don't have your Router next to the Mircowave or surrounded by mirrors. :lol:
Basil the 1955 series II

Image
Sleeper
Minor Legend
Posts: 1045
Joined: Tue Nov 08, 2016 3:18 pm
Location: Manchester ( Damp and Miserable ) and that's just the wife...
MMOC Member: Yes

Re: STRONG MAGNET/DASHBOARD

Post by Sleeper »

" The speedo moving parts are not ferrous material as far as I know " , I think you'll find the needle is moved by the attraction of a spinning magnet within a disc....

John ;-)
User avatar
geoberni
Minor Legend
Posts: 3544
Joined: Fri Aug 04, 2017 11:19 am
Location: North Leicestershire
MMOC Member: Yes

Re: STRONG MAGNET/DASHBOARD

Post by geoberni »

Sleeper wrote: Tue Jan 26, 2021 4:38 pm " The speedo moving parts are not ferrous material as far as I know " , I think you'll find the needle is moved by the attraction of a spinning magnet within a disc....

John ;-)
:oops: Darn it, I was forgetting they work on the eddy current Drag Cup principle. :roll:
I was just thinking of all the gears inside being brass & plastic, I forgot the drag cup.
Still I doubt a couple of Neodymium magnets several inches away would adversely affect it.
I'm not sure where the OP got the 60cm 'danger zone' from. I've never seen such info.
I'd keep them away from the data strip on a Credit/Debit Card, but apart from that... :)
Basil the 1955 series II

Image
neilmorey
Minor Fan
Posts: 151
Joined: Fri Aug 09, 2013 7:58 pm
Location: Edinburgh
MMOC Member: Yes

Re: STRONG MAGNET/DASHBOARD

Post by neilmorey »

I got fed up with the glovebox lid falling down and replaced the catch with 2 neodymium magnets. It never occurred to me that could they cause interference but I've not seen any issues with fuel pump which is not far away from that point, or anything else.

I'm sure you'll be fine but guess it could affect fuel gauge pointer if you were very close to it?
djk3816
Minor Friendly
Posts: 21
Joined: Thu Jun 20, 2019 12:37 pm
MMOC Member: Yes

Re: STRONG MAGNET/DASHBOARD

Post by djk3816 »

I found a better solution - non-permanent, double-sided tape. It's clear and 1mm thick and very strong. Easy to remove without marking paint and it is reusable too. Found on eBay £2.15 for 1meter x 12mm. Just the job :D
MorrisJohn
Minor Addict
Posts: 721
Joined: Sun Jun 21, 2015 9:41 am
Location: Glasgow
MMOC Member: Yes

Re: STRONG MAGNET/DASHBOARD

Post by MorrisJohn »

JOWETTJAVELIN wrote: Tue Jan 26, 2021 12:16 pm There was a fault in a signal box once where a track circuit indicator permanently showed 'occupied', after much head-scratching and testing the cause was eventually traced to the fish tank on the block shelf!
Haha, that’s a new one.
A bad day with my Volksie still beats a good day at work!

https://www.glasgowmoggies.com
Post Reply