Hoffman Amplifiers Tube Amplifier Forum

Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: jeff on February 24, 2012, 06:10:19 pm

Title: 6.3V DC heaters
Post by: jeff on February 24, 2012, 06:10:19 pm

Some amps use a full wave rect. on the 6.3V to get DC heater voltage.
 Isn't the DC of a full wave rect = 1.4 X AC?
 Won't that give you 8.82 VDC on your heaters?

Title: Re: 6.3V DC heaters
Post by: darryl on February 24, 2012, 08:06:29 pm

Quote from: jeff on February 24, 2012, 06:10:19 pm

Won't that give you 8.82 VDC on your heaters?

No, because there are other factors to consider. The most significant is the nominal 0.7 volt drop across each diode. This is insignificant when calculating B+ in the hundreds of volts, but it becomes an important part of the calculation at the 6-8 volt level.

Title: Re: 6.3V DC heaters
Post by: John on February 24, 2012, 08:41:30 pm

Is building a DC heater supply as simple and easy as doing the relay supply  on Doug's page? Curious minds,and all that. :)

http://www.el34world.com/projects/relay_switch5.htm (http://www.el34world.com/projects/relay_switch5.htm)