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Audio and Video Talk
Valves / Vacuum Tubes
Wim Bouwman PreAmp
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<blockquote data-quote="handsome" data-source="post: 747166" data-attributes="member: 772"><p>Do the sums but 6N6s want 750mA each....</p><p></p><p>A word of caution with low voltage DC supplies especially with regulators: always overspec the transformer. Losses are big so minimum 9Vac for 6.3V on a 7806 and possibly more if you using a 317. Minimum double the required current. I have built a couple and popping the oscilloscope onto the circuit often revealed the regulator was dropping out through the ripple troughs...plus you have to deal with mains variations. I use 12V transformers for 6.3V with a small (less than 1R sometimes) CRC filter before the reg. Too much initial capacitance can make the trannies resonate with the current spikes even though it solves the ripple trough problem so rather filter better oerformance all round.</p><p></p><p>If you up to hacking consider running the heaters in series or even better current regulate but then you will need even more voltage.....</p></blockquote><p></p>
[QUOTE="handsome, post: 747166, member: 772"] Do the sums but 6N6s want 750mA each.... A word of caution with low voltage DC supplies especially with regulators: always overspec the transformer. Losses are big so minimum 9Vac for 6.3V on a 7806 and possibly more if you using a 317. Minimum double the required current. I have built a couple and popping the oscilloscope onto the circuit often revealed the regulator was dropping out through the ripple troughs...plus you have to deal with mains variations. I use 12V transformers for 6.3V with a small (less than 1R sometimes) CRC filter before the reg. Too much initial capacitance can make the trannies resonate with the current spikes even though it solves the ripple trough problem so rather filter better oerformance all round. If you up to hacking consider running the heaters in series or even better current regulate but then you will need even more voltage..... [/QUOTE]
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Audio and Video Talk
Valves / Vacuum Tubes
Wim Bouwman PreAmp
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