LED lights & associated resister?

[Nicholas123]

I have a very attractive LED type light that came with my boat that clamps around a vertical pole type hand hold (I would post a photo but don't understand the technique) & looks for all the world like an operating theatre light.Anyway,so far I have been using it with 3 or 4 AA batteries in the unit but the other day I discovered that it seemed much brighter with the 12v cigarette type plug lead supplied with it so I thought I would make a good job of it & plumb it in permanently.

Sadly I went at it like a bull at a door pulling off the plug only later discovering that it has a resister (I think that's what it is) connected to the central pin inside the plug which I f ucked. (It's about half inch long & about 3/16" diameter.Basically grey & has a gold band around it followed by two black bands then a brown one).So the problem is replacing it.
Is it a resister & if so is it possible to buy just one from somewhere as opposed to about a gross?

 

[savageseadog]

Maplin. I think you have a 100 ohm resistor, it's not critical so any value of plus or minus 10% or more

 

[NickRobinson]

brown black black would be 100 ohms? gold is the tolerance, 5%?

https://www.google.co.uk/search?q=r...hyylms%2Fresistor-colour-code-5-bands;467;376

 

[JumbleDuck]

Basically grey & has a gold band around it followed by two black bands then a brown one).So the problem is replacing it.
Is it a resister & if so is it possible to buy just one from somewhere as opposed to about a gross?

You're reading it backwards. That's brown-black-black, which is 1-0-0 or 10 x 10⁰ = 10 ohms. (the gold ring shows +/- 5% tolerance) I think Maplins will sell you them singly, and there are plenty of sellers on eBay ... ten for a quid, incuding postage, at http://www.ebay.co.uk/itm/20-pcs-Me...0-25W-1-from-1-Ohms-to-820-Ohms-/271410630694

 

[st599]

I have a very attractive LED type light that came with my boat that clamps around a vertical pole type hand hold (I would post a photo but don't understand the technique) & looks for all the world like an operating theatre light.Anyway,so far I have been using it with 3 or 4 AA batteries in the unit but the other day I discovered that it seemed much brighter with the 12v cigarette type plug lead supplied with it so I thought I would make a good job of it & plumb it in permanently.

Sadly I went at it like a bull at a door pulling off the plug only later discovering that it has a resister (I think that's what it is) connected to the central pin inside the plug which I f ucked. (It's about half inch long & about 3/16" diameter.Basically grey & has a gold band around it followed by two black bands then a brown one).So the problem is replacing it.
Is it a resister & if so is it possible to buy just one from somewhere as opposed to about a gross?

The coloured bands give the value of the resistor

It's a 3 band colour code - Brown = 1, Black = 0, Multiplier = Black = 10^0 = 1 so it's 10 Ohms
Gold means +/- 5%

The only issue is the power rating - Mpalin will sell in singles.

 

[JumbleDuck]

brown black black would be 100 ohms?

The first two digits are the value and the third is the multiplier, so 100 ohms would be 10 x 10¹ which is 1-0-1 or brown-black-brown.

 

[VicS]

You're reading it backwards. That's brown-black-black, which is 1-0-0 or 10 x 10⁰ = 10 ohms. (the gold ring shows +/- 5% tolerance) I think Maplins will sell you them singly, and there are plenty of sellers on eBay ... ten for a quid, incuding postage, at http://www.ebay.co.uk/itm/20-pcs-Me...0-25W-1-from-1-Ohms-to-820-Ohms-/271410630694

You say 10 ohms others say 100 ohms.

Its a hell of a long time since I played with this sort of thing but you posted just as I was thinking 100 was not right!

 

[ianj99]

Its a 10ohm resistor. You need a larger value if you want to increase the voltage from 6v (4xAA) to 12 (more like 14-15 with the engine running) so use a 27ohm (27R)

(assumming the led is the common 1watt type - ie approx 0.3amp @ 3v, so 9v drop at 0.3a = 30R (27 is a standard value), and of power rating: 9v * .3 = 3watts minimum

Here is a calculator: http://www.digikey.co.uk/en/resourc...version-calculator-resistor-color-code-4-band

A 4watt 27 ohm resistor will be physically larger (about 25mm x 6mm) so is there room for it, and it will get pretty hot.

 

[nimbusgb]

Assuming this is not a troll.

You need to size the resistor to the number of LED's and the supply voltage.

if you keep increasing the input voltage the LED's will get brighter and brighter until they suddenly go very dark .................. permanently.


how many LED's?

 

[savageseadog]

The first two digits are the value and the third is the multiplier, so 100 ohms would be 10 x 10¹ which is 1-0-1 or brown-black-brown.

10 ohms seemed too low for 12V which is why I said 100 "I think"

 

[ianj99]

10 ohms seemed too low for 12V which is why I said 100 "I think"

Its 10. If you read the OP, it was intended to be used on AA batteries - 4.5 or 6V, so 10 is fine but too small for 12v so 27R is more appropriate. (Most led lamps are either 1 watt or 3 watts, usually 1watt when run from batteries = 3v @ .3a, which is 3v drop across a 10r resistor hence 6v needed from 4 AA cells - 3v drop across the leds, 3v drop across the resistor.)

 

[Nicholas123]

Assuming this is not a troll.

You need to size the resistor to the number of LED's and the supply voltage.

if you keep increasing the input voltage the LED's will get brighter and brighter until they suddenly go very dark .................. permanently.


how many LED's?

Blyme I seem to have opened a can of worms & it is certainly not a troll.

There are four separate clusters in the unit incorporation I think three or four led type lights in each unit.(I'll check when I'm next down the boat).

I'll see if I can sort out a photo & post it because it is a very unusual interesting light it seems to me.I don't think it has a makers name on it & I have never seen anything like it.

 

[JumbleDuck]

You say 10 ohms others say 100 ohms.

10 ohms seemed too low for 12V which is why I said 100 "I think"

http://bit.ly/13W2jtz

However, using a resistor is a pretty crude way of doing it it. If the light is to be permanently wired in it would be better to fit a proper voltage stabilised supply for it.

 

[elton]

http://bit.ly/13W2jtz

However, using a resistor is a pretty crude way of doing it it. If the light is to be permanently wired in it would be better to fit a proper voltage stabilised supply for it.

In that instance it would be better to fit a constant current source.

For some reason, the "infinite number of monkeys" scenario springs to mind.

 

[VicS]

Blyme I seem to have opened a can of worms & it is certainly not a troll.

There are four separate clusters in the unit incorporation I think three or four led type lights in each unit.(I'll check when I'm next down the boat).

I'll see if I can sort out a photo & post it because it is a very unusual interesting light it seems to me.I don't think it has a makers name on it & I have never seen anything like it.

I think people are bored at this time of year.

If all you want to do is find a resistor to replace the one you damaged then the colour code has identified it as 10 ohms. All that remains is to determine the wattage rating. If this resistor simply drops the volts from 14volts ( 12 volt system with engine running) to 6 volts ( 4 x AA batteries) then it will be dropping 8 volts .

Now power dissipated = V²/R = 8x8 /10 = 6.4 watts So the next available power rating above 6.4 watts will fit the bill. I think that will probably be 7 watts and it will be wire wound ......... Physically rather larger than the original which from your dimensions I guess may only be 2 watts. Hopefully you will be able to accommodate a larger component

http://www.maplin.co.uk/p/wirewound-7-watt-10-ohm-resistor-l10r

 

[nigelmercier]

There are four separate clusters in the unit incorporation I think three or four led type lights in each unit...

If it normally runs from 4 AA batteries, there cannot be more than 2 LEDs is series without some other electronics to boost the voltage. It it runs from 3 AA batteries, there is only enough voltage to power a single LED. I'm guessing that it therefore has an internal voltage booster, and the resistor is there as an overall 1A current limit, rather than a voltage dropper.

 

[Nicholas123]

OK boys I am in a position to put you out your misery

I went down my boat yesterday & swapped the batteries with some new ones & Ureeka! It lit up as well as when connected via the cigarette lighter lead so I don't think I will bother with it,it is not worth the additional hassle.


Another good bit of info was that it has a makers sticker on it & via the magic of google I have managed to track down the very thing http://www.amazon.de/RANEX-LED-Schirmleuchte-LUCIA-5000-185/dp/B002RLGLPI

Problem solved,thanks for your replies & attempts at assistance.:encouragement:

 

[VicS]

OK boys I am in a position to put you out your misery

I went down my boat yesterday & swapped the batteries with some new ones & Ureeka! It lit up as well as when connected via the cigarette lighter lead so I don't think I will bother with it,it is not worth the additional hassle.


Another good bit of info was that it has a makers sticker on it & via the magic of google I have managed to track down the very thing http://www.amazon.de/RANEX-LED-Schirmleuchte-LUCIA-5000-185/dp/B002RLGLPI

Problem solved,thanks for your replies & attempts at assistance.:encouragement:

"The very thing" looks to me like the light fitting for a garden parasol/garden table

http://www.amazon.co.uk/Garden-Univ..._sbs_lp_2?ie=UTF8&refRID=1QEZAMX2E2ZKSYS2YYBD

 

[Nicholas123]

"The very thing" looks to me like the light fitting for a garden parasol/garden table

http://www.amazon.co.uk/Garden-Univ..._sbs_lp_2?ie=UTF8&refRID=1QEZAMX2E2ZKSYS2YYBD

That's the baby & I luv it

PS:Mine is the grey/silvery looking variety.

PPS:There seems to be some confusion because on that original link I provided that black version is described as have 24 led's I believe.It confused me.Mine has the 16 led's & I do think they are some sort of older model & I dare say not as bright as the more modern offering.Hope this helps.

 

[nigelmercier]

PPS:There seems to be some confusion ... 24 led's I believe... Mine has the 16 led's ...

16 LED http://amzn.to/1tQOiKl
24 LED http://amzn.to/1wYOiCw

Neither mentions a 12V cigarette type plug lead though.