Dimmer was RE: [simpits-tech] Anyone awake?

Sun Jul 2 16:22:10 PDT 2006

Just so I know I got this right, you're trying to do the following:

1.  Use the original 737 Oeco Dimmer control that takes 28vac/400hz and
steps it down to 5vac/400hz.  From the same control, you can adjust the
brightness of the lamps from 0-5vac, correct?

2.  You have 110vac 400hz that you are stepping down to 28vac/400hz, this is
then being fed to the dimmer control from the overhead 28v primary bus.

Do I have this correct?

If so, I'll forward this to Mike.

One suggestion, can you gut Oeco dimmer and just use a high current
potentiometer?  You can run 5vac lamps using 5v dc.  The lamps will work,
they just won't last as long.  Once they burn out, you can replace them with
LED's, as they are making these same lamp footprints using LED's instead of
incandescent filament types.  All the lighting I'm using are the old
filament types and I'm going to use 28v dc.  When they burn out, I'll
replace them with the LED types.  They make the footprint lamps in LED's and
in different voltages, usually 5v, 13v, 24/28v.  They are a bit more
expensive but will last longer than you and I put together.  You can also
dim these LED's as well.  Maybe not as dim as the incandescent lamps, but
you can dim them down to the threshold voltage, you just may have to move
the pot a little less.

This way would be much easier.  Less efficient, but much easier.

Jay

-----Original Message-----
From: simpits-tech-bounces at simpits.org
[mailto:simpits-tech-bounces at simpits.org] On Behalf Of David C. Allen
Sent: Sunday, July 02, 2006 2:56 PM
To: Simulator Cockpit tech list
Subject: Dimmer was RE: [simpits-tech] Anyone awake?

Hi Jay
It is a light dimmer for the 737 fwd overhead lightplates. Part of 
the dimmer circuit is copied with permission from Forrest Cook.

I have changed the circuit and added and impedance matching 
transformer between the amplifier and the Oeco Dimmer control. The 
new diagram is located @

http://www.737flightsim.com/Light_Dimmer4a1.pdf

Ask if he has any suggestions to make it simpler, of if something 
needs to be added.

U1: is a LM324N quad op-amp

U2 : is a LM386 - Low Voltage Audio Power Amplifier

Q1: is a MosFet

What I am trying to do is use the original Oeco Dimmer control, it is 
(T31) on the diagram.

Thanks

David

At 01:21 PM 7/2/2006 -0500, you wrote:
>I got a buddy who's an EE.  What are you trying to do with the circuit and
>what do I need to ask him?  I can forward it to him and find out.
>
>Jay
>
>-----Original Message-----
>From: simpits-tech-bounces at simpits.org
>[mailto:simpits-tech-bounces at simpits.org] On Behalf Of David C. Allen
>Sent: Saturday, July 01, 2006 4:46 PM
>To: Simulator Cockpit tech list
>Subject: RE: [simpits-tech] Anyone awake?
>
>Hi Jay
>I would like to use the original 737 autotransformer dimmers for the
>lighting system. I am using DC for the non-dimmed circuits.
>
>I have some large 110VAC 400Hz to 28VAC 400Hz stepdown transformers.
>I also have the 28Vac to 5Vac 400Hz stepdown transformers.
>
>So my ideal 400Hz voltage is 110Volts.
>
>The 400Hz flow is 110Vac to the 110Vac to 28Vac stepdown transformer,
>then the 28Vac autotransformer dimmer, then 28Vac to 5Vac stepdown
>transformer, then to the 5Vac lighting circuits.
>
>Is anyone a electronics expert?
>
>I attached the PDF, but I think it will be striped. So here is a web link
>
>http://www.737flightsim.com/Light_Dimmer3.pdf
>
>I would like to know if you guys think it would work.
>
>It is basically a DC power dimmer operating at 400HZ, and I use the
>400hz to generate the dimmer control voltage using the original 737
>variable autotransformer
>
>David
>
>At 04:17 PM 7/1/2006 -0500, you wrote:
> >True, but how many VA do you need?  I only have a backup ADI that need
> >26/400.  All the other stuff is 115/400 and is stepped down internally.
> >
> >Jay
> >
> >-----Original Message-----
> >From: simpits-tech-bounces at simpits.org
> >[mailto:simpits-tech-bounces at simpits.org] On Behalf Of David C. Allen
> >Sent: Saturday, July 01, 2006 4:06 PM
> >To: Simulator Cockpit tech list
> >Subject: RE: [simpits-tech] Anyone awake?
> >
> >At 02:05 PM 7/1/2006 -0500, you wrote:
> > >My understanding is that the transformers are wound different.
Although,
> > >I've also been told you can run a 60Hz transformer at 400 hz but not
the
> > >other way around.  I bought a couple of transformers just for this
>purpose
> > >but never got around to testing them.
> >
> >Yes the low frequency is the governing factor with the transformer so
> >a 60Cps should work at 400Cps
> >
> > >Patience on eBay will turn up static boxes that will do 26vac 400hz.
>I've
> > >managed to snag two of them for under 200 bucks.  They don't show up
too
> > >often but when they do, they aren't cheap either.
> >
> >And most are less than 1000VA. :-(
> >
> >
> >David
> >
> > >Jay
> > >
> > >-----Original Message-----
> > >From: simpits-tech-bounces at simpits.org
> > >[mailto:simpits-tech-bounces at simpits.org] On Behalf Of David C. Allen
> > >Sent: Saturday, July 01, 2006 1:57 PM
> > >To: Simulator Cockpit tech list
> > >Subject: Re: [simpits-tech] Anyone awake?
> > >
> > >Hi Gene
> > >My Ham friend has a ton of them, but I would like to find a way to
> > >change a simple 12vdc to 110vac 60Hz Inverter to 400hz. Some say it
> > >is just a RC frequency component change.
> > >
> > >David
> > >
> > >
> > >At 11:50 AM 7/1/2006 -0700, you wrote:
> > > >David C. Allen wrote:
> > > >>Trying to find an inexpensive way to supply 28vAC 400CPS
> > > >Your best bet would be to find a cheap dynamotor on ebay.
> > > >
> > > >g.
> > > >
> > > >
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