Two transformers in series, what happens to the ratings? - Page 3

hugobross · 13th January 2002, 05:12 PM

Indeed, subwo1 and Jeremy_Wolf, putting those capacitors in series is not a good idea, what about placing two times two of the transformers in parallel, put the secondary windings in series to get +110V AC, GND, -110V AC; then rectifiing, then stabilizing with capacitors (it will be hard to find caps which can handle this voltage), then reduce voltage with zener diodes or special IC's to get the right voltage for the pre-stage (diff. amp and voltage amplifier); use the +110V and - 110V for the end-stage (current amplifier) (again it will be hard to find transistors for this voltage).

Due to the high voltages, this maybe too complicated. This method is only usable for class AB, class B; otherwise (class A) the maximum dissipation of the zener or IC must be very high.

Best regards,

HB.

subwo1 · 13th January 2002, 06:13 PM

Yep, hugobross, when I first started experiementing with amps, I was experiencing many of the type of problems Jeremy has been. I had to obtain different voltages than the transformer was capable of, but I wanted to use the parts I already had. What I finally did was to connect a secondary of a second transformer to the center tap of the main one, and connect the other end of the second's secondary to ground. Just so long as the second tranformer's secondary is rated for twice the current as one of the center tap branches of the first, they work fine in this way. The result is the second transformer gets voltage doubled and boosts The positive and negative rails by 1.4 times that amount.

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13th January 2002, 05:12 PM	#21
hugobross diyAudio Member Join Date: Jun 2001 Location: Flanders, Belgium	Indeed, subwo1 and Jeremy_Wolf, putting those capacitors in series is not a good idea, what about placing two times two of the transformers in parallel, put the secondary windings in series to get +110V AC, GND, -110V AC; then rectifiing, then stabilizing with capacitors (it will be hard to find caps which can handle this voltage), then reduce voltage with zener diodes or special IC's to get the right voltage for the pre-stage (diff. amp and voltage amplifier); use the +110V and - 110V for the end-stage (current amplifier) (again it will be hard to find transistors for this voltage). Due to the high voltages, this maybe too complicated. This method is only usable for class AB, class B; otherwise (class A) the maximum dissipation of the zener or IC must be very high. Best regards, HB.

13th January 2002, 06:13 PM	#22
subwo1 diyAudio Member Join Date: Jan 2002 Location: North American Continent	Yep, hugobross, when I first started experiementing with amps, I was experiencing many of the type of problems Jeremy has been. I had to obtain different voltages than the transformer was capable of, but I wanted to use the parts I already had. What I finally did was to connect a secondary of a second transformer to the center tap of the main one, and connect the other end of the second's secondary to ground. Just so long as the second tranformer's secondary is rated for twice the current as one of the center tap branches of the first, they work fine in this way. The result is the second transformer gets voltage doubled and boosts The positive and negative rails by 1.4 times that amount.

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