What Resistors to Buy?

Thread Starter

BR549

Joined Mar 29, 2010
3
No, unfortunately the lens seems permanently attached to the LEDs. I know nothing else about these lights. What's more, I know next to nothing about current, amps, Ohms, watts, voltage, etc.

My research has determined that with certain specifications, a proper calculation can be done to determine the resistors needed. However, these specifications don't seem to be available.

And so I'm hoping for a ball park idea of what resistors to buy. Otherwise I'll be left to try different ones and use a process of elimination.
Can you open one up and take a photo of what it looks like inside?

How much current does one of these use?
 

rjenkins

Joined Nov 6, 2005
1,013
Many built-up LED lamp units use active electronics, effectively a small switched-mode power supply, to drive the LEDs efficiently.

These can not be dimmed with external resistors; either nothing happens or they turn off/flash when the power is too restricted.

If however the item you show is simple LED+Resistor circuit already, then it can be dimmed with an additional external resistor.

But: it's not possible to calculate a resistor value and power rating without knowing either the wattage and voltage of the light unit or the current it's drawing.

We need either electrical measurements, specifications or internal photos to work with.
 

rjenkins

Joined Nov 6, 2005
1,013
There is nothing to stop you experimenting to see if they can be dimmed.

Try connecting them using various small 12V filament lamps bulbs in series with the LED as resistors, like 1W, 3W, 6W sizes or whatever you can find.

You may find it dims the LEDs, or it may go out/flash/have no effect depending on the partucular lamp rating.

Knowing what bulb size causes a reasonable dim light (from the LEDs) will at least give us a ballpark idea of the led lamp power and what range of resistor values may work.
 
Top