Looks like tube +B supply is in series with supply for output stage ?
And 120R/150R would be to adjust heater from the 33Vdc ?
Looks like it would be easy to implement a regulated heater supply ?
And 120R/150R would be to adjust heater from the 33Vdc ?
Looks like it would be easy to implement a regulated heater supply ?
How about using a single trafo with 25V + 25V secondaries
One secondary for output stage, and the other for tube stage
Will there be any issues
One secondary for output stage, and the other for tube stage
Will there be any issues
tinitus said:
No opinions about using a common 25V+25V trafo ?
One winding for B+, and other for voltage doubler
Can work, but the HT will be less(105V instead of 120), than the original. But be careful, the transformer must be with independent secondaries (no internal connection between them!).
Sajti
Sajti
and usually the two secondaries are wound bi-fillar,
i.e. each turn is adjacent to (touching) the isolated version of it's partner winding.
One circuit is working at low voltage and the other circuit is operating at an elevated voltage.
The voltage stress across the winding insulation could quickly become "outside specification" of standard 25Vac transformers.
The 1500Vpk test if from primary to secondary.
What is the specification for secondary winding to winding voltage isolation?
i.e. each turn is adjacent to (touching) the isolated version of it's partner winding.
One circuit is working at low voltage and the other circuit is operating at an elevated voltage.
The voltage stress across the winding insulation could quickly become "outside specification" of standard 25Vac transformers.
The 1500Vpk test if from primary to secondary.
What is the specification for secondary winding to winding voltage isolation?
the two adjacent windings have the same voltage on them.
let's connect each low end of the twin secondaries to power ground.
let's connect each of the high end of the twin secondaries to Power hot.
All along the winding the voltage in one winding is equal to the other winding. If you go to the next turn that is adjacent but on the other side the maximum voltage difference between adjacent windings is volts generated by one turn.
Now try connecting the low of one winding and the high of the other winding to power ground.
connect the other two ends to +power & to -power. the highest voltage between adjacent windings is two times the Vac of the bi-fillar windings. This is completely within the control of the transformer designer.
Now tie one winding to a low voltage and the other winding to a high voltage and the voltage between adjacent windings is completely out of the control of the transformer designer.
You MUST ask the transformer manufacturer what the voltage limit is between the windings. As far as I know, low voltage transformers do not have this quoted as part of the general specification.
let's connect each low end of the twin secondaries to power ground.
let's connect each of the high end of the twin secondaries to Power hot.
All along the winding the voltage in one winding is equal to the other winding. If you go to the next turn that is adjacent but on the other side the maximum voltage difference between adjacent windings is volts generated by one turn.
Now try connecting the low of one winding and the high of the other winding to power ground.
connect the other two ends to +power & to -power. the highest voltage between adjacent windings is two times the Vac of the bi-fillar windings. This is completely within the control of the transformer designer.
Now tie one winding to a low voltage and the other winding to a high voltage and the voltage between adjacent windings is completely out of the control of the transformer designer.
You MUST ask the transformer manufacturer what the voltage limit is between the windings. As far as I know, low voltage transformers do not have this quoted as part of the general specification.
Ok, thanks
But I dont see why it would be different with a seperate trafo being loaded with 35Vdc/6A into its secondary, being a low power trafo ?
But I dont see why it would be different with a seperate trafo being loaded with 35Vdc/6A into its secondary, being a low power trafo ?
tinitus said:
Ehhh, seems its not
Voltage from both trafos seems to be in series AFTER bridge/smoothing
Thats probably different
two separate transformers cannot have the secondary windings laid right next to each other.
The secondaries are isolated very effectively from the primary (that's the standard test ~1500V ).
You can couple either secondary to any sensible voltage, the secondaries can be @ ground and at 500V and you will have no problem.
You cannot do this with a bi-fillar wound pair of secondaries without first consulting the manufacturer.
AndrewT said:
Thanks Andrew
I have contacted AutomaticEurope
They want OPT specs
Not sure about the trafo specs for drive stage/voltage doubler
Any suggestions would be nice
Thinking about maybe having a EI trafo with double separate 27V windings
It seems like its possible to have windings side by side
Sent mail to Amplimo too
I suppose I could just use a small 15V-0-15V coupled in series for the 30V voltage doubler
And for the B+ 24V maybe just use a 12V-0-12V, coupled in series
And for the B+ 24V maybe just use a 12V-0-12V, coupled in series
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