Dimmer for (+) Side

[mbopp]

I'd like to install a dimmer for the interior lights. I have the control panel and wiring exposed but the (-) side of the lights wasn't run to the panel. I do have a ground wire available.
Does anybody know of a dimmer that switches the positive side of the lights?

[mbopp]

They're LED's, apparently unregulated. The problem is that the ground side wasn't accessible, that's why I had to rig a high side dimmer. Others on the GD forum are using a $30 dimmer, plug & play.
The control panel has the light switches, slide controller switches, water pump, and water heater switches. It wasn't hard to remove to get behind it.
For the MK-2 version I'll try a P-channel MOSFET instead of the bipolar transistor.

[MrWizard]

4a dimmer for LED light system 5-24v compatible

LED dimmer Amazon

[wa8yxm]

What kind of lighting
FLorsecent (Sorry I know of none)
LED
Incandascent?

Now, with LED and Incandescent you can use either a simple resistor type dimmer or a Pulse With Noise maker,, ER, Modulator dimmer.

Many of them out there. but alas. I can't point you to any.

[MrWizard]

Why would you be in the control panel, for the dimmer
Mount it in the cabinet near the living room lights

[mbopp]

Update - since I already had a cheap low side dimmer I dusted off my memory and built a current source from a PNP transistor and a couple of resistors. Haven't checked it for electrical noise yet since I didn't add any filtering to it. But it works!

[GordonThree]

ok, so i'm thinking, we need to know more about the LED to design a solution.

are the LED unregulated, or do they have on board regulator. is the on board regulator linear or switching?

my experience shows, applying any form of "dimming" to the DC-DC switching regulated LED module is going to end badly.

[mbopp]

A bit of clarification - I'm trying to dim the 12V LED lights in the living area. So OK, I need a high side 12V LED dimmer.

[DrewE]

For DC, a ground reference is required. What is not required for a high side dimmer is that the ground from the load goes through the dimmer. Most of the readily available cheap PWM dimmers work by switching the negative side of the circuit rather than the positive side, so the negative connection from the fixture must go through the dimmer module. A high side dimmer modulates the positive lead.

For traditional AC dimmers, they will work in either leg of the circuit without needing any reference to the other as they're effectively just bipolar voltage sensitive switches (a triac triggered by a diac or something similar). That, of course, is uninteresting for 12V RV lighting.

[GordonThree]

Guys, is there even such a thing as a floating high side dimmer? I cant see how one would operate without a ground or - connection.

[RoyB]

Just be aware the LED lights require a whole different kind of dimmer than the 12V Incandescent automotive bulbs do. Automotive dimmers can use a variable 12VDC source where the LED DIMMERS require a PULSE WIDTH source of 12VDC or something to that effect. LED dimmers are not expensive however - check AMAZON with LED LIGHT DIMMER in search on GOOGLE followed by the word AMAZON... Should not be too hard to find both polarities on the fixtures... Has to have both + and - DC levels to work...

RV Color code is WHITE for frame ground (-12VDC) and any colored wire including white with a color stripe on it for +12VDC.

Roy ken

[DrewE]

What you need is called a "high side dimmer." They are not all that easy to find, at least when compared with low-side dimmers.

PXD RV LLC (which I know nothing about other than that they have a web site) has a few dimmers and modules that are listed as high side dimmers. See, for instance, the various ATDIMxx modules.

[GordonThree]

Are these led or regular lights? 12v or 120v?

A simple rheostat might work. Any other gizmo will need both + and - to work.

https://www.amazon.com/a11082400ux0170-Ceramic-Variable-Resistor-Rheostat/dp/B015Z191E4

[enblethen]

Make and model of proposed dimmer?