I have a transformer with 6,3 sec. winding which was used for direct heateing in an older tube radio. What is the best way to get 6,3 VDC out of it. Tubes to be heated are two ECC88`s so I need cca 0,8A after regulatoin. Useing 2A/80V bridge and one 10000uF/25V cap over rails, I am geting cca 8,3VDC. Can I use let say 47K resistor to lower voltage? BTW. how if someone can say, 6DJ8, ECC88, 9622 react on direct AC heating?
Thanks!
Marijan
Thanks!
Marijan
I have a transformer with 6,3 sec. winding which was used for direct heateing in an older tube radio. What is the best way to get 6,3 VDC out of it. Tubes to be heated are two ECC88`s so I need cca 0,8A after regulatoin. Useing 2A/80V bridge and one 10000uF/25V cap over rails, I am geting cca 8,3VDC. Can I use let say 47K resistor to lower voltage? BTW. how if someone can say, 6DJ8, ECC88, 9622 react on direct AC heating?
Just a 2.5ohm 5 watt resistor after the cap is the simplest solution. There is nothing wrong with burning off a couple of watts to get the correct heater voltage.
John
There is another way to skin this "cat". Have the 6.3 VAC winding feed a "full wave" voltage doubler made from Schottky diodes. Use big 'lytics in the doubler stack. The doubler feeds a 7812 3 terminal regulator. The regulated 12 VDC feeds the 6922 heaters wired in series. The 6922 draws 300 mA. of heater current. You are good to go if the 6.3 VAC winding is rated at 1.2 A. or more RMS.
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