[simpits-tech] 5v AC for lighting?

[Gene Buckle]

On Fri, 2 Mar 2012, dabigboy at cox.net wrote:

>
> ---- Gene Buckle <geneb at deltasoft.com> wrote:
>> On Fri, 2 Mar 2012, dabigboy at cox.net wrote:
>>
>> Matt, unless there is specific circuitry between the power input and the
>> lamp that _requires_ AC, you can run them on 5v DC with no problems.
>> Bulbs don't care about ac/dc.  LEDs on the other hand _require_ DC.
>
> Awesome, I will give it a shot then. I did try 5v DC on my Gables navcom, and nothing happened....perhaps I missed a pin or something (this was before I hackerized the connector), or maybe the weak adapter I was using did not deliver sufficient current.
>
>> Note that aircraft panel lighting systems are dimmable by using a variable
>> transformer that takes 28v AC @400Hz in and can output 0..5V AC out.
>
> That would explain why all my diagrams and placards on radios etc 
> indicate 5v AC needed for lighting. So what happens if I just vary DC 
> voltage? Nothing?
>
It should work the same.  Remember, incandescent bulbs don't care about 
the polarity of the power, nor the waveform.  Incandescent lamps actually 
last longer under DC because the element isn't being stressed at 60 (or in 
this case 400)Hz.

g.


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