[simpits-tech] AC dimmers and transformers

[Matt Bailey]

On Wed, 26 Nov 2014 10:36:23 -0600
Cris Harrison <phoenixcomm at gmail.com> wrote:

> On 10/27/2014 01:02 AM, Matt Bailey wrote:
> > Question: What sort of dimmer device is typically used in old
> > business jets? Just a standard triac? I'm trying to figure out
> > exactly what is in my Sabreliner.
> >
> > Second question: how tolerant are typical aircraft AC transformers
> > and power regulators to variations in frequency? For instance, I
> > have 115v/400hz coming off my inverter, but it breaks down to 5v AC
> > for lighting (and 26v AC for other stuff). I'm wondering how
> > critical it is to maintain the 400hz frequency.
> >
> OK I have a dimer Boeing 7xx stuff its made OECO  #200-16408-02 NSN 
> 5950-00-920-1174
> It is a Variable Transformer 3 leads:
> 
>  1. Top or power via an internal switch
>  2. Bottom or power return.
>  3. Wiper or dimmed voltage to the lamps
> 
> You will most likely have to run 400 Hz as when you run lower 
> frequency’s  ie. 60 Hz it will get very hot...
> If I remember the cores of the 400 Hz transformers use a different
> metal in the laminations.
> You have to remember that you can run lighter weight & smaller 
> components at the higher frequency.
> You can run 400 Hz via a 60 Hz transformer but it will /sing/. What I 
> found out is that you can try audio transformers.
> Enjoy
> ~~ Cris H

Thanks Cris, that is helpful info. With this in mind, I don't think I
want to try 60hz on my nice original dimmers. I need to pop my dimmers
out again, I seem to recall they only have two leads.

I think I could use an Arduino and a simple circuit to make 400hz, as
long as the dimmers respond OK to a square wave. I'd just have to put
power directly to the dimmers instead of the main AC hookup in the
inverter area (since I really don't have a way to feed 115vDC to the
Arduino 400hz circuit). But right now I am really leaning towards
wiring the main 115v 400hz circuit to the (working) avionics inverter.

-- 
Matt Bailey

Keeping It Real:
Sabreliner 60 Flight Simulator
Serial # 306-61 - N1JX
http://sabrelinersim.com