The power supply described below can be used to supply Francy or Francesca. It can be used also to power  other tubes like SV 811 or 845, provided you fix the adequate heater voltage.

RULES TO FOLLOW

As you're dealing with high voltages you must pay very much attention not to touch any part under tension.
As usual I follow this general rules:
• Verify several time the circuit. Avoid being in hurry when you do this, nor do it at night.
• The first time you connect to power line, verify the circuit under low-voltage conditions. I do that inserting a 40-100W lamp in series to the circuit. This is an old trick that can avoid you great problems.


 
 

• Start with one channel
• Connect only one  trasformer each time.
• Heather supply circuit , Verify the voltage output under low-voltage (lamp inserted) and no tubes.

If everithing is ok you should measure a tension a little above normal condition. Then insert the tube: the lamp should flash and if everithing is ok the light should decrease while the filamet glow red. Now you can exclude the lamp and verify the correct filament tension.
• HIGH Tension Section (900v). Disconnect filament circuit and delay circuit, take away tubes and insert the lamp. When powering the lamp should flash only one time indicating that the capacitors are charged.

To measure tension use a highly insulated tester with wires in good conditions. While measuring high voltages you MUST:
1. wear rubber shoes
2. have dry hand, (if you fear a lot, you can wear thick  rubber gloves, but i never use it).
3. use only one hand, while the other is in your jeans' pocket, to avoid that your hart is passed by a discharge (that's highly probable if you touch the wires with both hands)
4. you should measure a tension that's slighly higher than normal.
5. Let about 10min. pass (check the voltage)  to discharge the capacitors.
• For the mid-tension (300V) i suggest you touse the same approach if you are a beginner.
• Fix the polarizing voltage in safe area (about -60/-70V)
• Then you may: insert tubes, connect the low/mid tension circuit directly to the power line BUT still put the lamp in series to the high voltage section. Connect a "poor" speaker to the output, and switch on.

If everithig is ok the lamp shoul flash, you may hear a little "hum" from the speaker. Check the bias to let some current flow to the 572.  If the speaker sends a whistle the amplifier is self-oscillating (never happend even with my "creative" cabling), you must check the layout.
Touching the input wire with a 1meg. resistor  the hum should increase a lot, indicating that the amplifier is working.
• Put the bias in a safe position (-60-70V)
• Thake away the lamp and fix  the bias checking the current in the tube by measurung the drop in the 10ohm resistor.
• My compliments ! you did a good job!

Best listening impression is obtainable after 30 minutes warming up.

Now the project: I've divided the supply into  two sections: HIGH/LOW voltage. 
 

 High Voltage Section...

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LoW Voltage Section
 


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 Delay Section...
  This's is necessary to avoid fuse blow-up, and not to stress tube too much during heather warming up.

Transistor are allowed here... ;)
 


 

That's all folks!