If you have 600V out of a 160T winding, to get 450V you would simply put a tap at 120T. Completely isolated outputs work the same but instead of a tap, you just have a separate winding for each output. This also points the way to get a low impedance feedback network (Less noise pickup) with a predictable frequency response without dumping too much power in the divider: You can set the output voltage for the previous example with a tap at 6T for a 30V feedback so for a 30K = 1mA feedback divider only 30mW needs to be wasted where feedback at the full 600V would consume 600mW for the same 1mA or 12W for the same 30K. This becomes an important consideration as the input parasitic capacitance of the regulator feedback is a constant, so increasing the feedback impedance to match the output voltage means the network low pass corner frequency moves lower as the output voltage increases.
Using a toroid core has a big advantage for a multi winding configuration with regard to the voltage ratio relationship: Unlike the open magnetic path of a drum core which can have fractional turns, toroids can only have an integer number of turns because only wires that pass through the hole at the center count as that section of the wire is the only one surrounded by a circulating magnetic field. Try it on a 60Hz transformer by unwinding a turn and observing there is little voltage change (relative to pulling the wire out of the hole) as the wire is pulled away from the outside of the core. In the case of an E-I core, you can have 1/2 turn increments as there are two holes. If you want a 1/4 turn from an E-I or a half turn from a toroid, you can drill a hole at the core center and pull the wire through it. As long as there is some load on each of the taps, the output voltages track fairly well: No load on un-sensed windings turns the rectifier/capacitor on that winding into a transient peak detector. jt -- You received this message because you are subscribed to the Google Groups "neonixie-l" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To post to this group, send an email to [email protected]. To view this discussion on the web, visit https://groups.google.com/d/msgid/neonixie-l/f81ece67-6b9a-4145-be6d-6fd4e3158f74%40googlegroups.com. For more options, visit https://groups.google.com/groups/opt_out.
