Check out this amp I have to sell. Note that has dual windings for the primary. YOu can wire it for 220 VAC but then use it at 120VAC and get voltages 1/2 of those listed. Between the dual primaries and dual secondaries you have the possibility for several different voltages. Perhaps one of them will be suitable?
http://www.diyaudio.com/forums/showthread.php?s=&threadid=56685
Let me know if interested and we can discuss a price lower than that I previously listed. I want to sell this guy.
Dick
http://www.diyaudio.com/forums/showthread.php?s=&threadid=56685
Let me know if interested and we can discuss a price lower than that I previously listed. I want to sell this guy.
Dick
New Transformer Question
>>Rectification raises the voltage
Umm, not really.
There is a way you can up the voltage, but it means rewinding the transformer. Transformers can either step up or step down the AC voltage on the primary. If you have more windings on the secondary than you do on the primary, then you end up with a step up transformer. Otherwise, it's a step-down transformer. The ratio of turns on the secondary to primary determines the ratio of secondary voltage to primary voltage.
As for current, you end up with the opposite effect. Since the effective power on the primary is always ~equal to the power on the secondary (minus a bit of loss) then if voltage goes up, current goes down. So, if you are stepping up voltage by a factor of two, the amount of current on the secondary will only be half of the amount of current on the primary.
Rectification follows the output of the transformer, and consists of diodes that will actually drop the voltage by about ~0.7V. Those go into the capacitors, which take the rectified signal (a series of pulses) and filters it back to ~DC.
As far as going from one DC voltage to another... the way any efficient PS does it is by creating AC from it and then stepping up or stepping down through a transformer or inductor and rectifying... since AC is where you already are, just worry about the transformer..
>>Rectification raises the voltage
Umm, not really.
There is a way you can up the voltage, but it means rewinding the transformer. Transformers can either step up or step down the AC voltage on the primary. If you have more windings on the secondary than you do on the primary, then you end up with a step up transformer. Otherwise, it's a step-down transformer. The ratio of turns on the secondary to primary determines the ratio of secondary voltage to primary voltage.
As for current, you end up with the opposite effect. Since the effective power on the primary is always ~equal to the power on the secondary (minus a bit of loss) then if voltage goes up, current goes down. So, if you are stepping up voltage by a factor of two, the amount of current on the secondary will only be half of the amount of current on the primary.
Rectification follows the output of the transformer, and consists of diodes that will actually drop the voltage by about ~0.7V. Those go into the capacitors, which take the rectified signal (a series of pulses) and filters it back to ~DC.
As far as going from one DC voltage to another... the way any efficient PS does it is by creating AC from it and then stepping up or stepping down through a transformer or inductor and rectifying... since AC is where you already are, just worry about the transformer..
increasing output voltage
If you were to use a voltage doubler, you'd get roughly 2.8 x the secondary voltage before you start loading it down. That's still under 40 V.
The 13.5 might be at rated load, so if you had big enough capacitors and music waveform rather than continous sine wave as in bench testing, you might have close to 40 V at light load.
Voltage regulation is poor with voltage multipliers, however.
You're still VA-limited (say 5*13.5 VA)...and very large capacitors cause high peak charging current which will cause heating in the transformer too.
Murray
If you were to use a voltage doubler, you'd get roughly 2.8 x the secondary voltage before you start loading it down. That's still under 40 V.
The 13.5 might be at rated load, so if you had big enough capacitors and music waveform rather than continous sine wave as in bench testing, you might have close to 40 V at light load.
Voltage regulation is poor with voltage multipliers, however.
You're still VA-limited (say 5*13.5 VA)...and very large capacitors cause high peak charging current which will cause heating in the transformer too.
Murray
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