First - disclosure - I am a hobbyist, with little electronic knowledge - but enough to get into trouble.
Please let me know if i am too inexperienced or in the wrong forum.

I want to use a 38mm 12v 0.45mA DC filament LED for a model. Power source output 12v 1A DC transformer from US residential power 120V AC. LED gets extremely hot.

 

Probably mean .45 amp.
Post a link to this LED.
That would be a 5 watt LED, also may require a heatsink

 

You could reduce the heat by reducing the LED current. How that's done depends on whether the LED has just a resistor or something more complex to limit current.

 

If the LED is too bright and too hot, you can reduce the power to the LED by putting a resistor in series. However, that still means redistributing the reduced overall power to another device.

Another solution is to pulse the current to the LED, what is known as PWM, pulse-width modulation.

 

Probably mean .45 amp.
Post a link to this LED.
That would be a 5 watt LED, also may require a heatsink

Link:https://ledlights.io/

Probably mean .45 amp.
Post a link to this LED.
That would be a 5 watt LED, also may require a heatsink

From the web site:
SPECIFICATIONS

• length: 38mm
• Voltage : 12V/45mA, 3V/100mA, 3V
• Item Type: BALL
• Current: 50mA/100mA
• Colour: Cold White/ Warm White/Red/Blue/Green
• Certification: CCC

 

Those specs are nonsense. Can you send a link to the listing you got them from? I suspect it is a COB LED and needs current limiting.

 

Hello,

Your link is for the complete website.
Do you have a direct link for your specific led?

Bertus

 

You could reduce the heat by reducing the LED current. How that's done depends on whether the LED has just a resistor or something more complex to limit current.

I may hav calculated incorrectly
Supply Voltage 12V
Forward Voltage 3
Forward Current45mA
Resistor Value = 200 OHM

which i did on the positive side on the filament bulb and the resistor became slightly warm and the led was noticeably dimmer but may work

 

Those specs are nonsense. Can you send a link to the listing you got them from? I suspect it is a COB LED and needs current limiting.

I don't know what a COB LED and the WEB site is all i have

 

I may hav calculated incorrectly
Supply Voltage 12V
Forward Voltage 3
Forward Current45mA
Resistor Value = 200 OHM

which i did on the positive side on the filament bulb and the resistor became slightly warm and the led was noticeably dimmer but may work

The resistor suggestion may be the solution. could i use a lower rated resistor that would still control the heat but brighten the led?

 

to confirm my understanding - forward voltage is the amount of voltage to get the led to work. and the forward current is amperage (watts?) the minimum needed for the led - yes?

 

to confirm my understanding - forward voltage is the amount of voltage to get the led to work. and the forward current is amperage (watts?) the minimum needed for the led - yes?

Amps and watts are not the same - my lack of knowledge....... oy

 

The 3 volts is the voltage across the LED with a current of 45ma.
You can reduce the resistor value to increase the current and brightness but don't exceed the current limit of the LED.
Will need to use a 2 watt rated resistor as well.

 

Appreciate everyone's feedback. I will use resistor in the mix. cheers

 

Hello,

Are these the leds you have?
https://ledlights.io/products/10pcs...iday-lighting-diy?_pos=4&_sid=71b62c9c8&_ss=r

Bertus

 

The web site shows two options:

100 mA at 3V

and

45 mA at 12V

These are two different products, selected by a drop down box.

So which did you order?

the 12V version should run from a 12V source with no resistor, and take about 45mA of current.

The three volt one takes a 3V supply and no resistor and takes about 100 mA.

Try running it at 3V with no resistor. If it lights it is the 3V version.

Neither of them should be extremely hot when run from the correct supply, as the are only 500 and 300 mW. They will be noticeably warm, but not hot.

I suspect you got the 3V version and are trying to run it at 12V.

 

Hello,

When you got the 3 volts version, you could try to put 4 of those filaments in series and power it with 12 volts.

Bertus

 

Hello,

Are these the leds you have?
https://ledlights.io/products/10pcs...iday-lighting-diy?_pos=4&_sid=71b62c9c8&_ss=r

Bertus

Yep - those are the ones

 

Yep - those are the ones

Which ones? That is for two different products, as explained in my previous post.

 

Which ones? That is for two different products, as explained in my previous post.

Sorry - 12v 45mA.