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For the electrical wizards plse

Discussion in 'General Land Rover Forum' started by gstuart, Jul 12, 2019.

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  1. gstuart

    gstuart D3 Grandad

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    so going to fit 4 x 12 volt dc led grain of wheat bulbs in my air vent dials so they light up at the same time as my instrument bulbs, which are dimmable via the dashboard dial dimmer switch like many landies have

    May i ask please , how can I make the LEDS also dimmable When i wire them into the instrument panel lighting via the dimmer switch I assume they won’t dim

    Was going to take a feed from the live out from the lighting dimmer switch and connect all the lives together and grounds together of the LEDs bulbs

    The cig lighter had a 12 volt dc supply for when the interior lights are turned on

    Would I have to use a resister of some sort plse

    Here’s the spec of the bulbs

    Product Specifications

    Bulb Colour: Green

    Size (mm): 3mm

    Cables length: 18cm

    Voltage (V): 12v DC / AC

    Current: 70mA

    Apologises for the daft question , just know there are some extremely knowledgeable members here where this would make sense

    Just an ideal time whilst having the dashboard apart

    Thank u

    Example pics

    041CF08F-AA64-47B7-9295-2113B3A3EABC.jpeg 04F7A075-3C79-4C08-B1EE-7752797A5DE9.jpeg 76D35F9A-CE76-4563-9F4A-B47B93E9713C.jpeg
     
  2. kermit_rr

    kermit_rr Well-Known Member

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    My first question is... why???
    My second question is... are the LEDs dimmable? Not all are
     
  3. gstuart

    gstuart D3 Grandad

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    Hi

    Basically would like the bulbs to be if possible the same as the others

    going to be wired into the main circuit to come on with the other dashboard lights , there all dimmable so wondered if these will be to

    Many thks
     
  4. Hippo

    Hippo Lord Hippo

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    How do the other lights dim? If yer going to tap oft that then yer need ter make sure it can cope with dimming the eggstra power. If it's just creating a volt drop across a variable resister int series then yer need ter make sure the variable resister can dissipate the heat.

    Strange mod ter want ter do.
     
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  5. gstuart

    gstuart D3 Grandad

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    Hi

    They dim just via a dashboard dimmer dial, Indeed each to there own ref mods
     
  6. windy81

    windy81 Active Member

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    Dimmable led's need an led dimmable switch and the led's need to be dimmable too but my information comes from domestic lighting which what I said is true.
     
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  7. My Old Landy

    My Old Landy Well-Known Member

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    A DC led can be dimmed by changing resistance, a domestic lighting led is a different beast as the cheap ones are usually on a capacitive dropper and a bridge rectifier as they are supplied by 240vac.

    Your led has a current draw of 70mA @12v. To protect them and allow 12v usage, they will have a built in resister as the forward voltage is typically between 2 and 3 volts (depending on chemistry used). So, if your dimmer (a Potentiometer) is capable of handling the current required for all leds attached, they should just work.
    To work out if it will be ok, check the amount of current consumed by all the leds you want to control and check that against the spec of the dimmer.
     
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  8. potus

    potus Well-Known Member

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    Dimming of the LED's may be achieved by softly closing the air vents to the desired level of brightness if the LED's are carefully positioned. :D
     
  9. gstuart

    gstuart D3 Grandad

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    C
    Many Thks and that’s a dam good idea , bless u for that :)
     
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  10. gstuart

    gstuart D3 Grandad

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    Also thought at first about wiring them up in series but think they will then be all different brightness so will connect all the pos and neg together then run the 2 x wires to the light power connection off the cigar lighter

    Thks again
     
  11. Nodge68

    Nodge68 Well-Known Member

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    70mA is a lot of current for a 2-3 volt LED with a simple dropper resistor. It's more likely that the LED in question has a switching LED driver in them, in which case the dimmer won't dim properly.
    The picture that Gary posted is a conventional incandescent bulb, which would be fine on a dimmer anyway, providing the dimmer switch can sink the extra current.

    I'm guessing the D3 will have an electronic dimmer, as those have been used for decades now.
     
  12. My Old Landy

    My Old Landy Well-Known Member

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    Ah, I'm old school, electronic dimmers are far too modern for me :)
    I did think that the current draw was a typo lol
     
  13. Nodge68

    Nodge68 Well-Known Member

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    I'm oldish school, but have embraced this modern all electronic world.:D
    I think it's an incandescent bulb, not a LED, hence the 70mA. 12 volts at 70mA is almost a 1 Watt bulb, which is what the picture looks like to me. ;)
     
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  14. gstuart

    gstuart D3 Grandad

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    Hi @Nodge68

    I think ur right u know with it being an incandescent bulb,, for the life of me I don’t know why I thought it was an LED

    Plus found where the pics came from https://www.disco4.com/forum/air-vent-illumination-90636.html

    So by that post should work fine , was going to use the cig lighting circuit to power them , is redundant at the moment because I changed the lower panel

    Don’t know what the max amps are for the dimmer switch, will check what the fuse is which should give me an idea

    Many thks as always

    Edit

    Lighting switch is 10 x amps
     
    Last edited: Jul 12, 2019
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  15. gstuart

    gstuart D3 Grandad

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    Many thks

    Dropped a clanger as there incandescent bulbs not LEDs , don’t know why I thought that

    Looked and the main lighting switch fuse is 10 x amps

    So with 4 x of them totalling 280 ma the conversion should be 0.28 amps
     
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  16. Hippo

    Hippo Lord Hippo

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    Yer can take power oft a 10amp fuse but bear int mind it's a 10amp feed, which is far higher than the rating of the cable on the bulbs. Put a series fuse in much lower to protect the weakest part of the circuit which is the cable.
     
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  17. gstuart

    gstuart D3 Grandad

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    Indeed , ur right , should have also put that , intend to put a fuse from the cig lighting circuit connector , 1 x amp fuse should be ok , have a few rolls of 17.5 amp cable spare which I was going to use up to connect the bulbs together

    Wondering though as the max is 10 x amp when I turn the lighting circuit in if it will pop the 1 x amp fuse , sorry for the daft question
     
  18. boguing

    boguing Well-Known Member

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    Gary, can you give us a link to the wiring diagram for the instruments? It's possible that you could link to the existing wiring and drive them from it, maybe with a loss of max brightness, but we'll see.
     
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  19. gstuart

    gstuart D3 Grandad

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    Hi

    Here’s the full wiring diagram manual http://media.disco3.co.uk/gallery/albums/userpics/11480/LRL183853501(LR3-Wiring).pdf

    Just got to find the page for u, ref the instruments

    Edit , instrument cluster page 70

    Lighting control switch page 156

    Illumination page 64
     
    Last edited: Jul 12, 2019
  20. gstuart

    gstuart D3 Grandad

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