Hoffman Amplifiers Tube Amplifier Forum

Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: fossilshark on June 05, 2023, 06:04:24 pm

Title: DC heaters and LED pilot light
Post by: fossilshark on June 05, 2023, 06:04:24 pm

Quick questions here, I am about to throw a rectifier for the heaters in the Wendigo preamp I am finishing up, valvewizard recommends 4700uf minimum for 300ma, so would 2 4700uf caps be fine for 3 12ax7 heaters?

Valvewizard also mentions a 1N4148 in antiparallel with the LED when powered by the heater that also helps with DC magnetization of the PT. Currently I have a 1N4007 with the cathode right on the LED (and of course a drop resistor) coming off a 6.3vac tap seperate to the heaters, should I be worried about DC magnetization of the power tranny?

Title: Re: DC heaters and LED pilot light
Post by: sluckey on June 05, 2023, 07:32:16 pm

The LED in that wizard circuit is only drawing about 10mA of current. Nothing to be concerned about. Seems kinda silly to me to even mention DC magnetization.

Also, since you will be running the filaments on DC you no longer need any protection diodes for the LED.