LED displays (TIL305, TIL308, etc.)

[Chuck Guzis]

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