Thanks. Could you please tell me how you get to those numbers? I'm a newbie and I'm not sure how to calculate it.
These are my numbers for the power supply needs:
From what I've read, the two heaters draw 6.3V at 600mA, that's 3.6W approx.
Plate load is around 2-3mA, less than 1W maximum dissipation for 12ax7s, so that's another 2W.
Why the 63mA fuse?
Thanks for your help, I'm a bit lost here.
These are my numbers for the power supply needs:
From what I've read, the two heaters draw 6.3V at 600mA, that's 3.6W approx.
Plate load is around 2-3mA, less than 1W maximum dissipation for 12ax7s, so that's another 2W.
Why the 63mA fuse?
Thanks for your help, I'm a bit lost here.
Hi,
So you have ~6W.
I = P/E
25mA = 6/240
allow for losses and stuff is approx X2 at these power levels = 50mA.
Microcurrent MDL's are in increments like 32, 63, 125mA, etc., so the closest one would be 63 (some listings say 64 or 65mA, don't worry).
Fuses in this range are expensive though.
Cheers!
gottlieb said:Thanks. Could you please tell me how you get to those numbers? I'm a newbie and I'm not sure how to calculate it.
These are my numbers for the power supply needs:
From what I've read, the two heaters draw 6.3V at 600mA, that's 3.6W approx.
Plate load is around 2-3mA, less than 1W maximum dissipation for 12ax7s, so that's another 2W.
So you have ~6W.
I = P/E
25mA = 6/240
allow for losses and stuff is approx X2 at these power levels = 50mA.
gottlieb said:Why the 63mA fuse?
Microcurrent MDL's are in increments like 32, 63, 125mA, etc., so the closest one would be 63 (some listings say 64 or 65mA, don't worry).
Fuses in this range are expensive though.
Cheers!
barretter said:Are you really worried that your 12AX7s are going to self-destruct? It doesn't seem very likely.
That probably is not the worry here. I always worry about unfused or improperly fused devices connected to AC mains - that would be my concern. Insulation fails, components short, and fires in electrical/electronic devices still cause significant property damage or worse. (Burning wall warts anyone?)
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