A little current is good

BuckWynd said:
Does anyone know if Van's lighting dimmers have an "Off" detent, or just a minimum-brightness position?

Thanks!
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Don't have one so not sure, but from the pic below there are only two wires off the Pot (potentiometer), which means there is likely no ON/OFF switch (detent). If there was a switch there would be two more wires from the Pot for the switch. You can buy Pot's with SPST switches piggy backed off the Pot from a local electronic supply house, Mouser or Digi-Key.

Min bright is pretty good place to leave it. The current flow is low and of little consequence to the planes total electical load, but a benefit of a little current going through incandescent bulbs is that it makes them last longer much longer. being less susceptible to fatigue from vibration. The current is too low for illumination. One wiring "trick" Piper used is supplying the electical power for the panel light dimmer control off the NAV light switch. With NAV lights off, there are no panel lights. NAV lights on, panel lights avaiable and adjusted with dimmer. Makes sense. If you want you could wire the Van's dimmer off the NAV light switch. Also another suggestion "tick" is twist the wire pair from the Pot. Probably not necessary with an analog dimmer like Vans dimmer, but its a good idea. PWM dimmers (pulse width modulation) can make noise, so twisting the wire pair is goodness for noise suppression.

cat-med_dimmer.jpg
 
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1.2V is the minimum

.. that you can set the variable regulator to. That's low enough to extinguish most LEDs and keep incandescents low enough not to be a problem. Feeding it from the Nav lights is a good idea.

The heatsink on these is wimpy. You should consider a larger one if you run bigger loads or run in hot weather. I've seen them cycle on and off due to overheating under these conditions. Its protected against thermal overload but that's a last resort.

John
 
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Thanks

George and John:

Thanks for the info. I should have said that I'll be using LEDs for my cockpit flood and map lights, so I wanted an "OFF" position.

I found that Perihelion Design has a much more compact dimmer that looks like it'll do the trick. It even has a On/Off switch.

As you'd expect, it's a bit more expensive than Vans' dimmers, though.
 
PJSeipel said:
They are a voltage regulator to provide a (variable) lower voltage to the lights. So, power side.

PJ Seipel
RV-10 #40032
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In order to be able to dim lights properly, they all need to be connected to the variable power side. This gets complicated when you want to monitor switched-power lamps.

Here's a circuit that allows you to sense any switched point (power, ground or reversing like flap motors). It connects to the Nav Light switch and the dimmer so that when the Nav lights are off, the lamps go to full brightness (daytime operation). When the Nav lights are on, the lamps dim normally.

It also supports an external lamp test function.

Follow the link to the datasheet, and you can see the schematic. You can build your own if you want or buy one from Aircraft Extras.

Vern
 
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