Resistor Help

Discussion in 'General Electronics Chat' started by ROCHRA, Oct 18, 2011.

  1. ROCHRA

    Thread Starter New Member

    Oct 18, 2011
    3
    0
    Im wiring lights in series, and have come to a part where I can only have 2 lamps. The bulbs I am using are 60v 10w, what is the best resistor to use to make the circuit 240v so the two lamps will work on the circuit. Thanks
     
  2. bertus

    Administrator

    Apr 5, 2008
    15,638
    2,343
    Hello,

    I would recommed the use of a transformer.
    A transformer from 240 to 120 Volts (if the lams are in series) or 240 to 60 Volts (if the lamps are paralel).
    A resistor would "burn" the also 20 Watts (the same as the 2 10 Watt lamps), wich is not economical.

    Bertus
     
  3. ROCHRA

    Thread Starter New Member

    Oct 18, 2011
    3
    0
    A transformer would be the best solution. However, the lights are going on a chaser, and will flash. Thats why I was looking at the resistor solution.
     
  4. Wendy

    Moderator

    Mar 24, 2008
    20,764
    2,534
    Have you thought of using a low voltage high wattage LED solution instead? Or even a 60VDC power supply powering up the bulbs?

    The alternative is solid state relays, if it is going to be a flash type scheme. You do not come across as an electrician to me, which is risky.

    The use of transformers is much more efficient, you will use less electricity using them. Resistors are not recommended.
     
  5. ROCHRA

    Thread Starter New Member

    Oct 18, 2011
    3
    0
    Thanks for the replies.... BUT..

    How can I not come accross as an electrician.

    I have a system of 60v 10w lamps. Nothing else.

    My question was,,, Has anyone got a recommendation what they have used with regards a resistor to complete a series circuit when I need to complete a circuit with just two lamps.. I can use 4 lamps and place two of them them out of sight, alternatively I can get two 110v lamps and wire a twin series or two 230v lamps and wire the last two in paralell, or I can place a resistor or resistors in the series circuit.

    A transformer isn't an option for two lamps, and LEDs are fantastic, but expensive, and I have the 60v 10w system wired and working except the last 4 on the series circuit.
     
  6. BJT_user

    Member

    Oct 9, 2011
    35
    8
    All things being perfect, what you will need is a 720 ohm resistor which will dissipate at least 20 watts. I'd go wtih a higher wattage rating because running at the peak rating of any component is asking for it to fail fairly quickly. Oh, and expect it to get spit-sizzlin hot. I'd use a 25 watt rating at the least.
    Here is a link to what a 25 watt resistor looks like. http://www.electronicplus.com/images/products/L25J700.jpg
    DO NOT use your standard 1/2 or 1/4 watt resistor from radio shack. Those just won't hack it.
    You can use a value that's close, like 700 ohms, which will make the lights burn a tad brighter, which shouldn't be a problem. Or go with a little higher like a 750 ohms, which will make the lights just a touch dimmer. Neither deviations should be noticeable.
     
    Last edited: Oct 18, 2011
  7. gootee

    Senior Member

    Apr 24, 2007
    447
    50
    I'd probably want to use a resistor rated for a lot more; probably at least 50 Watts. Also consider a heat sink for the resistor.
     
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