LEDs, - any electronic gurus? help needed.

[Rovernaut]

The little bulbs in my radio have blown. I was think on replacing the globes with LEDS.
Not being electronic savvy, can I solder these in place of blulbs or do led ned a resister some something as well to work ? or will 12 volt blow them?

[gqswb]

You will need a resistor, LED's have very little resistance so large amounts of current will try to flow through it unless you limit the current with a resistor.
1.2k - 3k will be fine. The only other problem may be is that a normal light bulb has a more omni patern of light where a LED is more directional so the lighting in your stereo may be a bit uneven.

[Rovernaut]

You will need a resistor, LED's have very little resistance so large amounts of current will try to flow through it unless you limit the current with a resistor.
1.2k - 3k will be fine. The only other problem may be is that a normal light bulb has a more omni patern of light where a LED is more directional so the lighting in your stereo may be a bit uneven.

Thanks,
The Eurovox radio I have as standard Manufacturers fit, has a globe to light the LCD station display and seperate globes to light up variuos buttons.
Eurovox offices arn't far from m,e it might be easier to actually call in and see if there spares section have the globes.

[gqswb]

The globes are common as, just get them from Jaycar or dick smith.

http://www1.jaycar.com.au/productView.asp?ID=SL2685&CATID=21&keywords=&SPECIAL=&form=CAT&ProdCodeOnly=&Keyword1=&Keyword2=&pageNumber=&priceMin=&priceMax=&SUBCATID=402

[Rovernaut]

gqswb -they are the ones. Mine have green condoms on them.
Thanks mate.

[Utemad]

The green condoms come off so just put them onto your new globes however they can break easy especially if they are old. My advice is to replace all the bulbs at once as the others will go soon I guarantee.

[gqswb]

You can get the coloured caps from most car audio workshops. Ask and see what other colours they have, Blue or red look's cool.

[Patroler]

I used LED's in the dash of my ute for speedo illumination, indicators etc, the super bright ones are the go, you'll need to run a resistor, go to http://www.ledsupply.com
It tells you how leds work and how to calculate resistances - different colour leds can run diffferent resistors.
Otherwise just get the replacement globes from the electrics shop.

[Troll]

Back of the dick smith catelog has the LED / resistor / voltage use chart.

[a187luv]

http://www.metku.net/index.html?sect=vi ... /index_eng

[-Scott-]

Back of the dick smith catelog has the LED / resistor / voltage use chart.

Which is OK if you already have one - they don't print them anymore. That data section in the back was fabulous - I used to keep old copies purely for the easy-reference data (but I don't know where they are any more. )

C'est la vie...

Scott

[-Scott-]

Back of the dick smith catelog has the LED / resistor / voltage use chart.

Which is OK if you already have one - they don't print them anymore. That data section in the back was fabulous - I used to keep old copies purely for the easy-reference data (but I don't know where they are any more. )

A very rough guide (for "normal" coloured LEDs - not blue or white) is allow 2V drop across the diode, then select a resistor which will give between 10 and 20mA with what's left.

Scott

[pig75]

Which is OK if you already have one - they don't print them anymore.

Yes they do 2004/2005 is available

[-Scott-]

Woo Hoo!

Thanks for the heads up.

Scott

[Utemad]

Which is OK if you already have one - they don't print them anymore.

Yes they do 2004/2005 is available

Don't know about DS but Jaycar took all their tech out of their catalogue and put it on their website instead. Reason was there was getting to be too much to fit it in the catalogue.

[ausyota]

Im wanting to run 4 x 5mm white LEDs in parralel http://www1.jaycar.com.au/productView.a ... BCATID=573
I tried to work it out from those links posted but Im too stupid
What resistor do I need?
Thanks
Paul.

[-Scott-]

First, decide if you want to run them at the "recommended" 30mA or the "max" of 100mA.

Assuming you're running from a 12V battery, which is closer to 14V while the engine is running, and a forward voltage drop of 3.5V you need to drop about 10.5V across a resistance.

One LED drawing 30mA requires nominally 350 ohms. 330 is a standard value, which will give you nominally 32mA. This is a 1/3W dissipation.

One LED drawing 100mA will probably have a voltage drop closer to the 4.3 V max, so presume we're looking to drop 10V. This works out quite neatly at 100 ohms. This resistor will be dissipating 1W, so make it a big one.

If you want to run all LEDs from one resistor then divide the resistor value by 5. However, power dissipation also goes up by a factor of 5, so you're dissipating more than 1.5W with 30mA LEDs, or 5W with 100mA LEDs. If you do this, remember that if 1 LED fails the other 4 will need to draw more current to maintain the same voltage drop across the resistor.

If you have space, it's probably better to use one resistor per LED - that way if one LED fails the others aren't affected.

Clear as mud?

Good luck,

Scott

[chimpboy]

Honestly, I wouldn't stuff around with this when replacement globes are readily available. It's not worth the hassles.

Jason