gstuart

gstuart

D3 Grandad
Full Member
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
 
kermit_rr said:
My first question is... why???
My second question is... are the LEDs dimmable? Not all are
Click to expand...

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
 
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.
 
Hippo said:
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.
Click to expand...

Hi

They dim just via a dashboard dimmer dial, Indeed each to there own ref mods
 
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.
 
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.
 
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
 
My Old Landy said:
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.
Click to expand...
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.
Hippo said:
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.
Click to expand...
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.
 
Ah, I'm old school, electronic dimmers are far too modern for me :)
I did think that the current draw was a typo lol
 
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:
My Old Landy said:
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.
Click to expand...

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
 
gstuart said:
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
Click to expand...
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.
 
Hippo said:
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.
Click to expand...

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
 
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.
 
boguing said:
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.
Click to expand...

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
 
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