Resistor Help

Thread Starter

ROCHRA

Joined Oct 18, 2011
3
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
 

bertus

Joined Apr 5, 2008
20,574
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
 

Thread Starter

ROCHRA

Joined Oct 18, 2011
3
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.
 

Wendy

Joined Mar 24, 2008
22,146
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.
 

Thread Starter

ROCHRA

Joined Oct 18, 2011
3
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.
 

BJT_user

Joined Oct 9, 2011
35
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:

gootee

Joined Apr 24, 2007
447
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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