Halogen bulbs, where to buy?

chuckcork
chuckcork Posts: 1,471
edited October 2008 in Workshop
Setting out for a nighttime ride, I've just found one of my 2 halogen lights was dead, and on inspection the bulb had gone (was working last week)

So just thought i'd ask, where it is possible generally to buy 6V / 3W halogen bulbs from? I know I can get some online e.g. SJS Cycles, or a lower wattage (from CRC), but would rather avoid shipping costs higher than the bulb cost while having correct light output.

Do car parts shops tend to carry such, or are they only likely to have 12V?

I remember years ago shops carrying light bulbs for torches but can't remember seeing any recently, and I don't know if they would do in any case?
'Twas Mulga Bill, from Eaglehawk, that caught the cycling craze....

Comments

  • System_1
    System_1 Posts: 513
    Not sure what type of bulb you're after (MR11, screw in etc) but Maplin or any other electronic type place would be a good start if you have one close by.
  • chuckcork
    chuckcork Posts: 1,471
    System wrote:
    Not sure what type of bulb you're after (MR11, screw in etc) but Maplin or any other electronic type place would be a good start if you have one close by.

    Maplin don't list them on their website and I checked in the local store a few weeks ago and couldn't find any then.

    Re Raleigh, maybe one of their local distributors has something, I'll check in the morning, though being Ireland likely to be expensive!
    'Twas Mulga Bill, from Eaglehawk, that caught the cycling craze....
  • redvee
    redvee Posts: 11,922
    Maplin list 6v MR11, I had this problem some weeks back and somebody else pointed out the units in 6v then I found out the battery was kaput and gave me a 10 min runtime :( but a new 6v 4.5ah SLA was under £9 :)
    I've added a signature to prove it is still possible.
  • whyamihere
    whyamihere Posts: 7,708
    DIY shops have them. You can actually run 12V bulbs by the way, they'll just give out half the power, so you might have more luck looking for 6W 12V bulbs.
  • chuckcork
    chuckcork Posts: 1,471
    whyamihere wrote:
    DIY shops have them. You can actually run 12V bulbs by the way, they'll just give out half the power, so you might have more luck looking for 6W 12V bulbs.

    A 6W 12V bulb will work with a SON dynamo? Would it even fit into a Schmidt E6?
    'Twas Mulga Bill, from Eaglehawk, that caught the cycling craze....
  • andrew_s
    andrew_s Posts: 2,511
    Bike +, £4 each, £3.5 p+p on orders under £50
  • whyamihere
    whyamihere Posts: 7,708
    chuckcork wrote:
    whyamihere wrote:
    DIY shops have them. You can actually run 12V bulbs by the way, they'll just give out half the power, so you might have more luck looking for 6W 12V bulbs.

    A 6W 12V bulb will work with a SON dynamo? Would it even fit into a Schmidt E6?
    They should be the same size as long as you get the same type. For example, all MR11 bulbs are the same size (not sure what type of bulb an E6 takes though).

    In terms of power it will be fine. I used to run 12V 20W bulbs in my Cateyes because they were easier to find than the 6V 10W bulbs it was supposed to take. Your dynamo will put out 6V and the standard bulbs will draw 0.5A, and as P=IV, the power output is 3W. A 12V 6W bulb will also draw 0.5A, but as they are only being supplied with 6V instead of 12, the power output will still be 3W.
  • Try CPC Farnell it's similar to RS Components and should stock them

    rammie
  • aracer
    aracer Posts: 1,649
    whyamihere wrote:
    chuckcork wrote:
    whyamihere wrote:
    DIY shops have them. You can actually run 12V bulbs by the way, they'll just give out half the power, so you might have more luck looking for 6W 12V bulbs.

    A 6W 12V bulb will work with a SON dynamo? Would it even fit into a Schmidt E6?
    They should be the same size as long as you get the same type. For example, all MR11 bulbs are the same size (not sure what type of bulb an E6 takes though).

    In terms of power it will be fine. I used to run 12V 20W bulbs in my Cateyes because they were easier to find than the 6V 10W bulbs it was supposed to take. Your dynamo will put out 6V and the standard bulbs will draw 0.5A, and as P=IV, the power output is 3W. A 12V 6W bulb will also draw 0.5A, but as they are only being supplied with 6V instead of 12, the power output will still be 3W.
    Err, no. Running 12V bulbs in an actual 6V system is a really bad idea. The bulb will be horribly inefficient - you'll get much less light for the power input than you would giving the same power to the correct voltage bulb, since you are undervolting it (standard rule of thumb is 40% light output for 10% lower voltage). Meanwhile if you give a 12V 6W bulb only 6V, then (ignoring the fact the resistance will change a bit because it's running cold) it will only draw 0.25A, hence will only run at 1.5W. Did you not notice how much dimmer the 12V 20W bulbs were in your Cateye compared to the proper ones?

    However a 12V bulb MAY work OK with a dynamo. It depends whether there's a voltage limiting zener in the lamp (I'm not sure if an E6 does). If not, then the dynamo itself will happily chuck out 12V at 0.5A rather than the 6V 0.5A it's rated at - it's just that you'll have to be going faster to do that, so lower speed lighting will be poorer. The only problem then - which I suspect may actually be quite a serious one - is that the bulb will be running at 6W and putting out twice the heat the light is designed for, which may cause a problem with things melting.

    I'd really recommend getting the proper 6V bulbs - and unfortunately you're not going to find them in any normal shop, only a specialist bike shop, or maybe at Farnell or RS (but I suspect that's unlikely - in any case Farnell has a £20 min order, and RS postage isn't that cheap I don't think).
  • chuckcork
    chuckcork Posts: 1,471
    I did a check and Evans have them listed in their web shop, I'll be in London next week so maybe the shop in Kingston will a couple....in the meantime, trying to resurrect a Busch + Muller light that was my primary last year, only I snapped off the mounting on the light itself, so am doing a bodge with washers and epoxy.

    Transfer the bulb from my primary E6 to the secondary and I'll have enough light again!
    'Twas Mulga Bill, from Eaglehawk, that caught the cycling craze....