Zener as power tap?

[petemoore]

  Say you have a zener diode, between a transformer and ground, [as used to drop B+ in tube amps] so that there is a 10vdc difference across the diode.
  could this 10vdc be used as a power tap?
  Perhaps a larger value like 15v or so could be used, then 'processed' [filtered or diode rectified] for power tap?

[gez]

This method can be used, but it can produce a lot of noise.  You usually need a current limiting resistor too to stop it being fried.

More common is to use it as a stable bias for a power transistor.

Edit.  This method is a little redundant now that regulators exist.