For those of you who are interested in the inner workings of an Output Transformer, I'll show you how I do it; and where to get the parts. Let us do a push-pull transformer for the EL34 tube.
A simple configuration is Class A push-pull. From the data page at http://tdsl.duncanamps.com/show.php?des=EL34WXT I get this:
A P/P (triode) 400 - - 130 - 142 - 220 shared 5,000 16.5 3 Pair of tubes
So it is going to be a 16.5 watt output transformer that should be able to handle a max current of 142mA. The anode load is 5000 ohms and the speaker load I choose as 6 ohms.
Next I need some idea of what Afe (cross section of the rectangular core that is in the centre of the bobbin; expressed in mm^2) I need to pump out 16.5 watts.
From Turner's web page ( http://www.turneraudio.com.au/output-trans-pp-calc.htm ) I use this formula:
Afe =300Xsquare-root(power output needed)
thus: =300 X sqr(16.5)=1219mm^2
To get the tongue width if the laminations to be used I square root the Afe = sqr(1219)=35mm
Tongue sizes comes in these standard sizes at AMC: 20mm, 25mm, 32mm, 38mm, 44mm, 51mm, 63.5mm
I choose the 32mm size of the EI96 (1.25 inch). Thus I go with a 32X32mm bobbin on a 32mm stack of EI96 laminations.
Next I'll work out what thickness copper I need for the Primary and secondary. That depends to some extent on my layering arrangement I am going to use. That is a whole topic on it's own
......
to be continued
A simple configuration is Class A push-pull. From the data page at http://tdsl.duncanamps.com/show.php?des=EL34WXT I get this:
A P/P (triode) 400 - - 130 - 142 - 220 shared 5,000 16.5 3 Pair of tubes
So it is going to be a 16.5 watt output transformer that should be able to handle a max current of 142mA. The anode load is 5000 ohms and the speaker load I choose as 6 ohms.
Next I need some idea of what Afe (cross section of the rectangular core that is in the centre of the bobbin; expressed in mm^2) I need to pump out 16.5 watts.
From Turner's web page ( http://www.turneraudio.com.au/output-trans-pp-calc.htm ) I use this formula:
Afe =300Xsquare-root(power output needed)
thus: =300 X sqr(16.5)=1219mm^2
To get the tongue width if the laminations to be used I square root the Afe = sqr(1219)=35mm
Tongue sizes comes in these standard sizes at AMC: 20mm, 25mm, 32mm, 38mm, 44mm, 51mm, 63.5mm
I choose the 32mm size of the EI96 (1.25 inch). Thus I go with a 32X32mm bobbin on a 32mm stack of EI96 laminations.
Next I'll work out what thickness copper I need for the Primary and secondary. That depends to some extent on my layering arrangement I am going to use. That is a whole topic on it's own
......to be continued
