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very basic question about power needed for light strip

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pfps823

New Member
Hi,
New to forum and new to doing these types of projects so sorry if too basic a question for here, but I'm trying to find the right power supply to hook up to 2 light sockets, each powering a UV-C lightbulb. The bulbs are each 11 volts, 3.5 Watts and 300mA. I tried wiring to a 12 Volt supply I had lying around, but the bulbs are barely powering up. Is there a formula for figuring this out? And a source like Amazon for buying what i need?
Thanks!
Peter
 

Les Jones

Well-Known Member
Most Helpful Member
What is the current rating of the power supply ? Have you measured the output voltage of the power supply when the bulbs are connected to it ? When you say that they are barely powering up how are you measuring the output as you can't see UV light ?

Les.
 

KeepItSimpleStupid

Well-Known Member
Most Helpful Member
We need a lot more information, unfortunately.

This sounds like a UV LED based lamp. If it is, then a LED power supply that can handle 300 mA at a compliance voltage of 2*11 V should work. It would not be recomended running it off of a constant voltage power supply.

2 of these: https://www.amazon.com/Constant-Waterproof-Lighting-Transformer-Aluminium/dp/B01MYBFR7U, one per each LED

should work.

You have 300 mA and a compliance of 2-20V. Your compliance would have to be 22V for 2 LEDS in series.
11 is between 2 and 20V and this PS is 300 mA constant current. It would not be dimmable.
 

KeepItSimpleStupid

Well-Known Member
Most Helpful Member
I can never believe Amazon. You shouldn't either.

Specs:

  • 35 Watt bulb with the power of UV C UV C light fights germs, kills airborne bacteria, viruses and mold spores
  • Germ Guardian LB1000 UV C Replacement Bulb is a 3
  • Important information
    Legal Disclaimer
    Statements regarding dietary supplements have not been evaluated by the FDA and are not intended to diagnose, treat, cure, or prevent any disease or health condition.

    Wattage
    3.5 Watts
if the picture is right, there is a filament. The resistance of a tungstein bulb is about 10x lower when cold. Your power supply needs to be able to provide that as a surge or be slow-start.

Call company, get specs if possible. P=VI, so 35=11(I); means 3.18 amps.
or 3.5/11 = 0.3A = 300 mA; You will need a >3.18 (~300 mA * 10) Amp power supply or a power supply with slow start forone bulb.

Aside:
I need a 4 Volt 2 Watt light bulb.
For What? (Watt)
No, two. (Watt)
 

Les Jones

Well-Known Member
Most Helpful Member
I do not see how a filament can produce UV light. I think the filament part may be just for starting, None of the information I found gives the voltage rating of the lamp but it does warn that it contains mercury. I suspect the lamp needs a relatively high voltage and some form of ballast such as a choke to limit the current. I think the UV is produced by ionized mercury vapour.

Les.
 

Pommie

Well-Known Member
Most Helpful Member
That's a germicidal light. It destroys bacteria by destroying the DNA in the cell. It will do the same to your retina and you'll go blind. Unless you are able to completely enclose it then you shouldn't use it. Note, when working you will see a faint purple glow.

What are you trying to do?

Mike.
 

pfps823

New Member
That's a germicidal light. It destroys bacteria by destroying the DNA in the cell. It will do the same to your retina and you'll go blind. Unless you are able to completely enclose it then you shouldn't use it. Note, when working you will see a faint purple glow.

What are you trying to do?

Mike.
Thanks. I'm using it to sterilize, and am aware I shouldn't look at it or have my skin exposed to it.
 

pfps823

New Member
I can never believe Amazon. You shouldn't either.

Specs:

  • 35 Watt bulb with the power of UV C UV C light fights germs, kills airborne bacteria, viruses and mold spores
  • Germ Guardian LB1000 UV C Replacement Bulb is a 3
  • Important information
    Legal Disclaimer
    Statements regarding dietary supplements have not been evaluated by the FDA and are not intended to diagnose, treat, cure, or prevent any disease or health condition.

    Wattage
    3.5 Watts
if the picture is right, there is a filament. The resistance of a tungstein bulb is about 10x lower when cold. Your power supply needs to be able to provide that as a surge or be slow-start.

Call company, get specs if possible. P=VI, so 35=11(I); means 3.18 amps.
or 3.5/11 = 0.3A = 300 mA; You will need a >3.18 (~300 mA * 10) Amp power supply or a power supply with slow start forone bulb.

Aside:
I need a 4 Volt 2 Watt light bulb.
For What? (Watt)
No, two. (Watt)

Thanks. So this should work?
 
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