Why do you need one?
Many of the old 28v turn and slip instruments work happily on 12v and the
regulator is likely to be electrically noisy. I thought RD Aviation sold a
ready-built converter?
Duncan McFadyean
On Sunday, June 02, 2002 8:14 PM, Carl Pattinson
[SMTP:carl@flyers.freeserve.co.uk] wrote:
> HELP !!!!!
>
> I need some advice on a voltage converter/ regulator that I have been
> building.
>
> For some reason no one makes a commercially available regulator that
boosts
> 12v up to 28V so that one can operate a 28volt aircraft device on a 12v
> Europa system.
>
> From time to time there have been published circuits on this forum for
such
> a device and I have eventually got around to attempting to build one.
The
> circuit is constructed around a LM2577 step up voltage Integrated
circuit.
> By changing the component values the output voltage can be changed. The
same
> circuit is published on P235 of the latest Maplin catalog.
>
> Anyway my problem is this. Having assembled the circuit I tested it on
the
> workbench and it works fine giving 27.8 volts across a 50 ohm dummy load.
> The trouble is that as soon as it is placed in a metal case the voltage
> immediately drops down to 13V.
>
> Losing the case is not really an option as it will probably affect the
other
> instruments and anyway even the proximity of a flat metal sheet (eg a
radio
> case) has the same effect. We tried grounding the case but it didnt work.
>
> Anyone in the know have any suggestions.
>
>
> Carl Pattinson
>
>
|