centre tap or floating heaters?

[lt cdr data]

which is best?

and bridge or full wave 2 diode recitication?

thanks

 

[Geek]

Hi,

I've used centre tap as well as floating w/one leg grounded with a 'lytic cap (2.2-4.7uF) in mic stages, where noise is very noticeable. I'd say there's at best a 6dB favor for the centre tap. However, if you tie the heaters to say, +30V, there seems moot difference between the methods.

 

[TonyTecson]

a two diode full wave bridge has one side of the transformer cut-off, doing nothing, at reverse phase.

a 4 diode full wave bridge otoh uses the full secondary winding at all times, therefore in terms of transformer utilisation is better the the 2 diode ones.

 

[cm_ls1]

i found

referencing the centre tap of the heater to 1/4 b+ with a voltage divider coupled to earth the quietest .

next best was grounding the CT

and floating produced quite a bit of hum

this is with ac heaters