LED displays (TIL305, TIL308, etc.)

[Scanning]

If  I need a small HV power supply " on-the-cheap " I visit the local photo
shop. The disposable cameras with flash have a nifty little DC-DC converter
built-in and the shops throw them all in the trash after the film has been
recovered. They run off of a single AA ( 1.5 VDC ) battery. The batteries
are usually at about 90% of their life still left. And did I mention " free
" .....

Best regards, Steven


> On 2 Oct 2008 at 18:29, Tony Duell wrote:
>
> > Alternatively, consider using a transformer 'back to front'. Start of
> > taking in mains and stepping it down to, say, 12V AC using a normal
> > transformer in the conventional way. Yo ucan rectify/smooth/regulate
that
> > for your logic supply. But then take another 220V-12V trasnformer and
> > connect the 12V winding to the secondary (12V) side of the first
> > transformer. You'll get around 230V from the other (original primary)
> > winding of that transformer.
>
> If you happen to have one handy in the USA, of course.  Although
> "universal" 95-240v transformers can be found in the US, most of the
> small ones (such as are found in wall warts) are 120vac primaries
> only.
>
> But if I had a 12vdc supply at sufficient current and needed to power
> some nixies, I'd be sore tempted to work up a boost supply using any
> of the currently available DC-DC converter ICs.  EDN/Electronic
> Design is full of such circuits (e.g. using the Maxim MAX1771).  Much
> more compact and not requiring much in the way of a DC filter
> capacitor.
>
> Where I'd draw the line is with any small signal application, such as
> a receiver using tubes/valves.  Those converter ICs can really
> generate a lot of RF noise.
>
> Cheers,
> Chuck