LED displays (TIL305, TIL308, etc.)

[Tony Duell]

> I was under the impression that old "B+ supply" transformers were 
> getting hard to find.  Not so, apparently.  I popped open a 1990's 

They're not _that_ hard to fimd, and there are plenty od workarounds.

Since nixie tube current is pretty low, and the supply doesn't have to be 
that well smoothed, you can use a voltage doubler (or even a larger 
diode-capacitor multiplier circuit) to get that voltage from a 
lower voltage trasnformer.

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. 

OK, it's inefficient, but it's fine for nixie tubes, 1 and 2 valvle 
headphone radios, and the like.

-tony