Dimmer pot $$

Usually, you get what you pay for.

Please educate me on the differences of a 3 pack from Amazon that cost a few bucks and the high dollar “aviation” pots.

I’m having a hard time understanding how much better the variable resistor that cost 50 times as much is for controlling a light.

I guess there’s probably not any difference but you may have a better chance of finding a reliable alternative from somewhere more reputable than Amazon such as Farnell or RS?

Are they the same parts or cheap knockoffs? Quality does matter. I have a Bosch microwave that I installed about 4 years ago. I've replaced 4 door switches in that time. When I first bought them they were a few dollars, but are now about $7 or so. I bought 3 or 4 when I saw the original part. They are cheap switches sourced, I think from China, and when the roller contact gets depressed it stays stuck. I can replace a switch in about 10 minutes if I really want to do it quickly. Glad I'm not paying for a service call. I would gladly pay more for a quality switch that will last.

I actually built my own. I'm a radio amateur and have some knowledge of this stuff...
A 'variable resistor' might or might not work for what you need.
A lot of modern lighting is LEDs, and a variable resistor is not going to work very well for those. Generally you need a PWM dimmer instead. That's one that rapidly turns the power on/off with varying on duty cycle.

The issue with PWM circuits is they can make a lot of radio noise that gets into the intercom, etc.

Hence a cheap one may be really noisy... and the 'aviation' one probably isn't.
I've gone through the same headaches with USB ports in the plane.

I'm currently installing one in another plane and I'm going to try out this https://www.allelectronics.com/item/msc-10/10a-dc-motor-speed-control/dimmer/1.html
I don't know yet if this one is noisy or not. If it is I can probably do some circuit mods and fix it.

Dimmers

I bought two of tthese
Dimmers from SteinAir along with two LED strips. White & Red. I figure it's worth a little peace of mind knowing they probably tested before selling them.

When you say "aviation pots" a few different products come to mind. There's a rheostat, a standard 1 turn pot, and a pwm light controller.

I haven't seen a rheostat sell for under $60-75 dollars. They are a current limiter used with incandescent bulbs and have to be built to sink all the extra heat/wattage the bulbs don't get when you dim them. Depending on the fuse rating of the circuit, these should be able to turn 75-150 watts into heat for years without burning out.

2nd on the list is the standard 1k or 10k potentiometer. You can use this as a voltage divider for dimmable LEDs that don't require a PWM control signal signal. Anything from Amazon or digikey should work given you size it correctly. Cost should be under 5 bucks.

3rd is the PWM light controller, which is what stein and most aviation shops sell in the $20-50 range. This is a square wave signal generator used as a controller for the GAD27 light circuit or LEDs with an extra wire for a PWM input. Some LEDs can even be wired to send the PWM directly to the LED hot or ground side, but if you do that you have to make sure the PWM signal can source enough current to run the entire strip. Most chips limit the PWM signal around 10-50mA, so powering LEDs directly from this signal limits how long your string of lights can be. You'll have to look at each chips datasheet to determine the actual limits.

wirejock said:

I bought two of tthese
Dimmers from SteinAir along with two LED strips. White & Red. I figure it's worth a little peace of mind knowing they probably tested before selling them.

Click to expand...

I’m of the same opinion.

Will the same dimmer work for controlling the backlight in the Garmin boxes or does that one need to be a standard pot?

The Rheostat mentioned earlier is used to dissipate a lot of energy into heat. I wouldn’t ever buy one these days.
1. For incandescent lights, low power LEDs with dropping resistors, and input signals to dimming inputs on various boxes (all of which use dc signals), buy an LM317 voltage regulator for less than a dollar, attach it to a small heat sink, control it with almost any low power/low cost potentiometer.
2. For high power LEDs, as already mentioned, you probably need a PWM driver. Check for any radiated noise.