Need help with LEDs and resistance SOLVED

[BurbMan]

The back light on my 2002 Lance 811 camper has a Intellitec Touch-Lite. This is a just a touch pad on the exterior by the door that when you touch it lights the exterior light for about 30 seconds. It wires in parallel with the wall switch inside (see schematic on link to data sheet).

The inside switch is part of a bank of 4 lighted rocker switches (great idea so you don't forget to turn off the outside lights) including the dinette fluorescent light. Everything worked fine until I changed the outside fixture to an LED.

With the LED installed, turning on the dinette light causes the exterior light switch to glow at half bright and the exterior light to glow at half bright. If you turn on the rocker switch or touch the Intellitec pad the LED comes to full brightness like it should.

With the LED uninstalled, I still get the rocker switch glowing at half-bright with the Intellitec connected. If I add an old 1141 everything goes back to normal.

So it seems like the the Intellitec needs the resistance of an incandescent bulb to work properly.

So my choices are:
1. Put the old 1141 fixture back - but I'm trying to move everything to LEDs for boon docking efficiency with 1 battery and 100w solar.

2. Take the Intellitec Touch Lite out of the circuit - but it's pretty cool and I could see it being handy, so would like to keep it if I can.

3. Add some kind of resistor to the LED fixture so that it mimics an 1141 - but if I do that am I gaining any efficiency over an actual 1141?

Need some EE help here!

[MrWizard]

That's. Good news Congrats

[BurbMan]

SOLVED! I just converted the fluorescent fixture to LED and now the Intellitec touch switch works as normal! Call me the accidental electrician....

[MrWizard]

RV florescent fixtures are Known RF noise makers,
A choke on the power wire might help,
But the fixture itself is a broadcast antenna,
Some LED fixtures create their own RF noise,
Enough to interfere with radio and TV reception

[BurbMan]

Mex thanks for the detailed info! Where do I buy a thigamajiggy like pictured now that Radio Shack is gone?

A local friend suggested that maybe a choke on the power line to the fluorescent light might help? I only get this odd half-bright condition on the outside light when the dinette fluorescent is on.

My quick fix was to add another switch....the Intellitec module is easy accessed inside a storage compartment, so I added a rocker switch in that switch loop that effectively disconnects the IT switch.

With the IT switch isolated, the dinette fluorescent causes no issues with the outside LED. If we are away from the camper at night, then the dinette fluorescent would be off....then I can flip the rocker switch before I leave to bring the IT switch back online so I can use that function when I return to the camper.

I thought I had a bright idea of adding an incandescent bulb to the LED fixture and then separating the IT and wall switch circuits, so that the wall switch would turn on the LED and the IT switch would like the incandescent. Turns out any bulb smaller than an 1141 creates the same symptoms...A dual fixture would work but that's a project for another day.

[theoldwizard1]

BurbMan wrote:
3. Add some kind of resistor to the LED fixture so that it mimics an 1141 - but if I do that am I gaining any efficiency over an actual 1141?

No gain ! If you like that feature, stick with the 1141.

[MEXICOWANDERER]

30 watts. 300 ohm ADJUSTABLE RESISTOR.

Keep expanding the distance with the slide control. And limit the current to 1/10th amp.

At your given specs, this resistor may heat to .01 BTU

For you, start wide and slide the band until the problem resolves itself then clamp the band. Impossible to go wrong.

[MEXICOWANDERER]

Nope

There would be even more series resistance. Try a 1K 5 ohm resistor in the dinette power in to negative circuit. That problem would disapprear. It would draw down bleed threshold. I tried to not write the encyclopedia brittanica on this issue. The resistor I mentioned would exhibit a Delta T dissipation maximum of 12 watts. But minus the load of the LED lamp. Shoot, if you want no heat at all use a thirty watt resistor. Equal to 2.5 amps capacity. I do not do guesswork 🙂

[BurbMan]

A quick search on "LED load resistor" brought some auto parts store solutions, but all advise that they will heat up and not to install near plastic or paint, so they won't work.

What's interesting about this problem is that the half-bright condition only happens when the dinette light is on. When the dinette light is off, all are off.

What if I got a small resistor and put in series with the Intellitec switch? So when the LED lamp is operated by the wall switch there is no resistor in the circuit? But the switch loop going through the Intellitec would "see" a higher load?

[MrWizard]

How much do you use the exterior door light
Hours every night ?
Our just coming in and going out
No need for an LED fixture, if it's only going to be on 30 seconds

[MEXICOWANDERER]

No can do without roto-rooting the incandescent board and change ICs. Or not save milli-amp hours daily and install a pull down resistor. Zero energy savings
That would be rational with a difficult to change or extremely expensive emitter

Determine bulb number then look up BULB wattage on GOOGLE.

Then you need to order a power resistor that is physically big enough to light up repeatedly light up the LED without becoming too hot. A 10 watt wire wound resistor would be plenty I would think. Pure guesswork says a 12 ohm 10 watt ceramic resistor would be on the ballpark.

More guesswork suggests the resistor would not fit inside the lamp housing.



But the resistor would need to fit *somewhere* between the switch and lamp. This means the wire.

It's tough to describe the relationship in resistor size to the available room versus resistor size. Buy the resistor. They are cheap. Then find a space keeping in mind a small 18 AWG wire needs to tap into TAP INTO the existing switch call the tap a "T" tap into the existing wire.

This leaves the other terminal on the resistor not connected
It needs to have a second new wire

That wire has to go to a VERIFIED good chassis negative meaning "ground"
HINT use the terminal at the switch for your T tap.

Use ?" heat shrink over your soldered connections to the resistor.
.