Shop OBEX P1 Docs P2 Docs Learn Events
Simple 10w Flouresecent Light — Parallax Forums

Simple 10w Flouresecent Light

william chanwilliam chan Posts: 1,326
edited 2010-03-24 13:28 in General Discussion
I was thinking loudly the other day that our 240v AC mains voltage may be sufficient to strike a 10w 1 foot fluorescent tube by itself without increasing the voltage.

So, can I connect a 240v AC mains directly to a 1 foot 10w tube in series with a 1uF 600v X-Capacitor( to limit the current) and also in series with a 100 ohm 1w resistor (to snub the initial current surge) ?

Will it work? Will the tube light up?

▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
www.fd.com.my
www.mercedes.com.my

Comments

  • LeonLeon Posts: 7,620
    edited 2010-03-19 13:51
    I think those small tubes will work without a starter, but you will need a ballast.

    ▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
    Leon Heller
    Amateur radio callsign: G1HSM
  • william chanwilliam chan Posts: 1,326
    edited 2010-03-19 22:44
    I was hoping the X-Capacitor would work as a ballast.

    ▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
    www.fd.com.my
    www.mercedes.com.my
  • william chanwilliam chan Posts: 1,326
    edited 2010-03-24 03:55
    Will it work?
    Or will the fluorescent tube explode?

    ▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
    www.fd.com.my
    www.mercedes.com.my
  • LeonLeon Posts: 7,620
    edited 2010-03-24 05:48
    The ballast is needed to generate the striking voltage, as well as to limit the current. A capacitor won't work.

    ▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
    Leon Heller
    Amateur radio callsign: G1HSM
  • william chanwilliam chan Posts: 1,326
    edited 2010-03-24 06:26
    But from my estimates, the striking voltage of a 1 foot 10w tube is only about 200v.
    240v AC mains by itself is more than sufficient striking voltage.
    There is no need for coiled ballasts.

    ▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
    www.fd.com.my
    www.mercedes.com.my
  • Phil Pilgrim (PhiPi)Phil Pilgrim (PhiPi) Posts: 23,514
    edited 2010-03-24 06:56
    Small fluorescent desk lamps in the States (120VAC) sometimes use a ballast-free configuration like the following:

    [noparse][[/noparse]image deleted]

    Although I'm certain there was no ballast in such a lamp that I disassembled years ago, that lack flies in the face of good engineering practice, so I cannot in good conscience recommend the circuit that I posted here.

    -Phil

    Post Edited (Phil Pilgrim (PhiPi)) : 3/24/2010 9:19:19 AM GMT
  • LeonLeon Posts: 7,620
    edited 2010-03-24 07:32
    What limits the current?

    ▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
    Leon Heller
    Amateur radio callsign: G1HSM
  • Phil Pilgrim (PhiPi)Phil Pilgrim (PhiPi) Posts: 23,514
    edited 2010-03-24 09:16
    What, indeed. See comment above.

    -P.
  • kwinnkwinn Posts: 8,697
    edited 2010-03-24 13:20
    A series capacitor of the appropriate rating can also be used to limit the current provided it is AC across the capacitor.
  • william chanwilliam chan Posts: 1,326
    edited 2010-03-24 13:28
    Will 1uF 600v allow sufficient current for 240v AC?

    ▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
    www.fd.com.my
    www.mercedes.com.my
Sign In or Register to comment.