LED Dimming Question

[Sawaro]

So I have installed three LED pods as camp lighting in my camper shell, the only problem is they are too bright!

Does anyone have some suggestions for dimming them?

I think i can use a potentiometer as a dimmer, but i would prefer something like a three position switch. I could probally solder different resistors into a three position switch but that seems like a lot of trouble and prone to failure (especially considering my crappy soldering skills).

Any other suggestions/approaches would be much appreciated.

BTW I got the pods from Will at Sierra Expeditions
http://www.sierraexpeditions.com/index.php?l=product_detail&p=600

 

[UK4X4]

LED's don't like dimmer circuits

as you lower the voltage they simply turn off.

The easiest way is to set up a switch to limit the ammount of leds connected at any one time.

ie low light only 6 bulbs are lit v's 12 when on high,

soldering is a good skill to learn..

Clean iron-clean items to join- fresh flux core solder and as little heat as possible.

joining two wires....wipe both with emery cloth, tin each wire with solder seperately.

Position the two soldered wires together then run the iron down the join.

slide over heat shrink to protect the joint-shrink and your done

If the solders good it will be shiny- bad if dull.

 

[Yudda]

http://www.oznium.com/rotary-dimmer

Super simple, cheap and designed for LEDS

all my LED stuff i buy from oznium.


Rob

 

[ThomD]

http://www.oznium.com/rotary-dimmer

Super simple, cheap and designed for LEDS

all my LED stuff i buy from oznium.


Rob

Excellent. I want to point out that this dims the LEDs by rapidly turning them on and off. (Too fast for the human eye to see.) It does not just throw in some resistance to lower the voltage to the LEDs. So, a generic rheostat will not do the same thing.

 

[Sawaro]

Thanks for all the responses.

UK4X4:
I should have known it wouldn't be so simple. Do you have any suggestions about how i could wire up the scheme you describe?

As for soldering, thanks for the tips. i've done a fair bit, but my connections just don't seem that reliable, i guess i should practice more.

Yudda:
Thanks for the link, looks like a great site.

ThomD:
Great point, does this mean that the dimmed light will be unpleasant like florescents?

 

[DesertBoater]

there are a number of headlamp companies that use that type of technology for their dimming settings. I know that Black Diamond uses it and while it's not super obvious that it's flickering, if you wave your hand across your face or have any sort of quick movements in front of the light, you'll notice a sort of "strobe" effect. I think it's kinda a personal thing, it bothers the heck out of me, but folks that own BD headlamps don't seem to mind...just my 2c.

Cheers,
West

 

[ThomD]

ThomD:
Great point, does this mean that the dimmed light will be unpleasant like florescents?

I doubt it. The pulse rate is vey fast. As DesertBoater points out, this is how headlamps get dimmed.

 

[brained]

It's called pulse width modulation and you can build a controller yourself or buy one if so inclined.

 

[rusty_tlc]

LED's don't like dimmer circuits

as you lower the voltage they simply turn off.

The easiest way is to set up a switch to limit the ammount of leds connected at any one time.

ie low light only 6 bulbs are lit v's 12 when on high,

soldering is a good skill to learn..

Clean iron-clean items to join- fresh flux core solder and as little heat as possible.

joining two wires....wipe both with emery cloth, tin each wire with solder seperately.

Position the two soldered wires together then run the iron down the join.

slide over heat shrink to protect the joint-shrink and your done

If the solders good it will be shiny- bad if dull.

A couple of nits with this post;

It's a good idea to clean any flux off the solder joint before you cover it with heat shrink. By definition flux is corrosive, you really don't want to trap it inside the heat shrink.

Here in the US lead free solder is becoming the standard, it does not have a shiny finish even with a good solder joint. A better way to inspect the solder joint is to look for good flow over the metal with a smooth meniscus between the solder and metal.

 

[M.Bas]

It's called pulse width modulation and you can build a controller yourself or buy one if so inclined.

The circuits can be done much simpler:

And yes I know, the resistor in serie with the led hasn't been drawn.
I used this schematic to power a RGB high power led without problems, the pwm fequency is somewhere in the kHz range if I remember correctly.

Back in high school I started with one of those more complicated schematics and asked a teacher if it could be simplified a lot since it took to much space on the circuit board and he came up with this schematic.
Later I switched to a microprocessor controlled pwm circuit wich let me use even less components.

 

[rusty_tlc]

If you have the skills building a PWM is a good choice. Now days there are single chips that do the whole thing, National Semiconductor has a nice utility called web bench that will walk you through the design and create a printable schematic when you are done.

Everything you need can be purchased from Digikey, in my experience they have the best pricing for onsey twoesy quantities.

 

[off-roader]

As for soldering, thanks for the tips. i've done a fair bit, but my connections just don't seem that reliable, i guess i should practice more.

http://www.youtube.com/watch?v=I_NU2ruzyc4

Took miniature microscopic soldering course in the Navy. This video appears to teach good fundamentals that will help you learn the right way.

 

[rusty_tlc]

http://www.youtube.com/watch?v=I_NU2ruzyc4

Took miniature microscopic soldering course in the Navy. This video appears to teach good fundamentals that will help you learn the right way.

Where did you train, China Lake?

Excellent info in the video, I have the exact same Weller soldering iron in my home shop as the one shown in the scene on tip cleaning. They are a great iron and easy to find used since they were one of the most common soldering iron in the electronics industry for many years.

One note on "No Clean" flux. No clean flux becomes a conformal coating when "FULLY" activated, any flux that isn't fully activated is still corrosive and should be removed from the work. This is usually not a problem with flux cored wire solder, only when additional liquid flux is added to aid soldering.