Blue Led

[vmail]

just got some Blue LED for £1.00 each (£1.86 in Maplins), has any one else replaced their dash bulbs with LEDs?

[dawesy]

yep

[vmail]

how many LEDs have you got, and how much did you spend?

[Bibbs]

I'd have thought one per bulb and then if you get them for a pound each ..

[Boro Sera]

Dammit. Last month I sold about 200 Blue and Green LEDs for £20.00

Ho Hum

Rich

[knightrider]

on here we'd all but blue LED's if they were cheap i jus aint doin it cuz of the price

[Boro Sera]

on here we'd all but blue LED's if they were cheap i jus aint doin it cuz of the price

If I get another batch I'll give you all a shout.

(these came in for a job at work, but were supposed to be white. Quality control threw them in the skip. I retrieved them just in time. The electronics trade is by far the most wasteful industry I've come across.)

Rich

[Panzerbjorn]

Can you simply replace the bulbs with the LEDs? or do you have to put a resistor in the circuit?

Cheers

Panzer

[jaxx]

resistors yes cos the cars system will be on 12v unless you egt some special 12v ones but they are even more expensive

i think varad actually led replacement bulb cartridge setup things?

ask Ken nicely and hell tell you all about it

[vmail]

[+12V]---[LED]----[Resistor]---[GND], you will need to know how to solder

[dawesy]

how many LEDs have you got, and how much did you spend?

2 per bulb about £25 incl resistors just cot the switches and heater controls to do

[vmail]

why 2 per bulb?

[knightrider]

so there plenty brite enough

[vmail]

what resistors did you use, Ive got 470 Ohms with the 3.3V LEDs

[Boro Sera]

usually anything from 220 to 1000 Ohms (1k) will do.

The lower the resistor value, the brighter the LED. They will work off just about any DC voltage, it's only the current that needs limiting.....hence the resistor.

Unlike bulbs though which enit light in all directions, LEDs direct the light in about a 120 degree spread, so using two or aiming them will help loads. I've got two LED's lighting up the logo on the back of my Sera. I refracted the light through a perspex bar to overcome the directional limitations.

Rich

[vmail]

voltage on the car changes, LEDs are 20-30mA

at 12V the LEDs are at 21.4mA

at 16V the LEDs are at 29.9mA

at 16.1V BANG 30.2mA

how high will the voltage jump up in a car?

[Boro Sera]

Shouldn't go much above 13. There are regulator/rectifiers in the charging circuit to prevent this..

If it went too high all of the filament bulbs would blow too. Wouldn't be too good for the electronics either.

Rich

[dawesy]

to calculate the series resistor use a scientific calculator and the following formula

R=(Vs-Vf)/lf

where Vs isthe supply voltage, Vf is the forward voltage drop across the LED and lf is the forward current through the LED

example

for an LED of 20mA(lf) and 2.5v(Vf) to opperat from a 12V supply:

R=(12-2.5)/0.02=475ohms there for go for the nearest value to 475 ohms. i always work the supply voltage as 13 volts for auto us as the actual voltage is between 11.5 - 14.4 volts

[vmail]

Ive got crocodile clips that will do the maths for me