Have a desk lamp that will not work with a LED cob Bulb which was in it ( The LED bulb just lights and goes straight out ) , but have put a halogen bulb in and it works fine ! .
anything I can do to make it work with a LED cob bulb! .
Spike

 

It sounds like the bulb is defective.

 

It sounds like the bulb is defective.

Have tried it in another 12v supply ( Battery Charger ) and it works fine !

 

Did it ever work in the lamp?

 

Did it ever work in the lamp?

Don't know, was given the lamp ! .

 

If I had to guess, and with the amount of information I have, I have to...

Assuming the lamp is low voltage (12V), the LED is drawing too much current for the supply.

 

If I had to guess, and with the amount of information I have, I have to...

Assuming the lamp is low voltage (12V), the LED is drawing too much current for the supply.

It does say 12v in the heading !, LED Lights will use a lot less amperage than halogen bulbs !

 

What is the wattage of the halogen?

 

Hello,

There are 12 volts power supplies for halogen lamps that require a minimum load to work properly.
When the load is to low by the led, the powersupply could go blinking or even stop.

bertus

 

Hello,

There are 12 volts power supplies for halogen lamps that require a minimum load to work properly.
When the load is to low by the led, the powersupply could go blinking or even stop.

bertus

Hi
Thanks for that, yes do remember something like from before, so the question would be what would be the best way to apply another load ( Resistor in series ) if so what value would I be looking at to slightly up the load from ( I think 3w max) for the LED, really want to do the min, could start high and go down with he resistor, but what value would I start with ? .

cheers
Spijke

 

Hi
Thanks for that, yes do remember something like from before, so the question would be what would be the best way to apply another load ( Resistor in series ) if so what value would I be looking at to slightly up the load from ( I think 3w max) for the LED, really want to do the min, could start high and go down with he resistor, but what value would I start with ? .

cheers
Spijke

You can calculate if this is reasonable. What is the wattage of the working halogen bulb?

You will have to put the additional load in parallel, not series, to decrease the resistance and increase the current.

The downside of this is you will be just heating things up and using more power without getting anything else for it.

 

You can calculate if this is reasonable. What is the wattage of the working halogen bulb?

You will have to put the additional load in parallel, not series, to decrease the resistance and increase the current.

The downside of this is you will be just heating things up and using more power without getting anything else for it.

Hi
Thanks for your reply, yes sorry in parallel, yeh true I won't be benefitting from doing that, just an exercise really .

cheers
Spike

 

Hi
Thanks for your reply, yes sorry in parallel, yeh true I won't be benefitting from doing that, just an exercise really .

cheers
Spike

What is the wattage of the working halogen bulb?

 

Don't have a bulb for it, will tale 12v max 35A Halogen , but hope not go to has high as 35W though, hoping the LED will come on round 10W load including the approx 3W for the LED ! .

cheers
Spike

 

Don't have a bulb for it, will tale 12v max 35A Halogen , but hope not go to has high as 35W though, hoping the LED will come on round 10W load including the approx 3W for the LED ! .

cheers
Spike

That would require 7W to be dissipated by the resistor. That is going to get very hot.

 

That would require 7W to be dissipated by the resistor. That is going to get very hot.

Yes, could I not use 2 or 3 resistors to obtain the same results ! .

 

Yes, could I not use 2 or 3 resistors to obtain the same results ! .

Each resistor would get less hot but the total heat will be the same. You will be making a little desk heater.

 

Each resistor would get less hot but the total heat will be the same. You will be making a little desk heater.

I could just start with a high resistror and see what happens with the LED bulb, bit of a guessing game really, but what would be a high resistor to start off with !

 

Two suggestions: don't end every sentence with an exclamation point! That will make your writings easier to read! Also keep in mind that this just a science experiment that should be taken apart when you are done because what you are doing is impractal and can be dangerous! Thank you for taking the time to read this!

 

I would get the lowest wattage tungsten lamp that will fit and see if it works. Then measuring the resistance of that lamp will give you any idea of what the total resistance needs to be and you can calculate the resistor value.