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Audio and Video Talk
Valves / Vacuum Tubes
Sansui 1000A Transformers on chassis
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<blockquote data-quote="handsome" data-source="post: 761970" data-attributes="member: 772"><p>your tranny is probably built for 220V not the 240V we more commonly see now hence the increased voltages. I wouldn't stress too much about it. Build the amp assuming the correct voltages and use a resistor/diodes/bucking etc to bring them down. I know this sounds haphazard but building it will allow you to see the actual voltages. Plus doing it teaches you far quicker than trying to make sense of various equations and theories.</p><p></p><p>For HT you can (and should) incorporate the necessary (if at all) resistance into your filter. </p><p></p><p>Heater current draw is constant so a series resistor or diode(s) will work - better still aa pair of resistors in both legs of the heater wiring plus a pair of small caps (100nF ceramics) from + to - will give you some useful HF/RF filtering (this will work for both AC or DC - be sure to use cheap wirewound resistors though for their inductance). If you are planning on regulated DC for the heaters you will need at least 9-10VAC and 2x the required current. Low voltage linear supplies are hellishly inefficient and LM3x regulators need at least 3V drop out voltage.....</p></blockquote><p></p>
[QUOTE="handsome, post: 761970, member: 772"] your tranny is probably built for 220V not the 240V we more commonly see now hence the increased voltages. I wouldn't stress too much about it. Build the amp assuming the correct voltages and use a resistor/diodes/bucking etc to bring them down. I know this sounds haphazard but building it will allow you to see the actual voltages. Plus doing it teaches you far quicker than trying to make sense of various equations and theories. For HT you can (and should) incorporate the necessary (if at all) resistance into your filter. Heater current draw is constant so a series resistor or diode(s) will work - better still aa pair of resistors in both legs of the heater wiring plus a pair of small caps (100nF ceramics) from + to - will give you some useful HF/RF filtering (this will work for both AC or DC - be sure to use cheap wirewound resistors though for their inductance). If you are planning on regulated DC for the heaters you will need at least 9-10VAC and 2x the required current. Low voltage linear supplies are hellishly inefficient and LM3x regulators need at least 3V drop out voltage..... [/QUOTE]
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Audio and Video Talk
Valves / Vacuum Tubes
Sansui 1000A Transformers on chassis
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