This Hybrid PSU Pls Teach Me

[sumotan]

Hi All,
Came across this psu & would appreciate your kind tutorial & explanation

1. Transformer is a Lundahl with HV 350 Ac output, not sure if it is 350-0-350v. If I use other tranformer with 350-0-350 do I leave the CT unconnected or ?
2. Does this hybrid rectifier circuit behaves like an SS diode bridge where voltage multiplication is higher as compared to tube rectification ?
3. What is the advantage of using such a circuit ?

Many

thanks

 

[Ketje]

What you have here is a bridge rectifier on 2x350V giving 2x350 x √2 is over 1kV DC out.
So skip the two diodes and connect the center tap to ground.
Mona

 

[tikiroo]

It looks like LL1650 has two 175V (no load) windings. The datasheet gives 350V output with the connections to 5 and 7 with 6-8 tied together. So a bridge rectifier is correct. It would behave like a SS bridge but with slow startup and increased voltage drop.

 

[Ketje]

It looks like LL1650 has two 175V (no load) windings. The datasheet gives 350V output with the connections to 5 and 7 with 6-8 tied together. So a bridge rectifier is correct. It would behave like a SS bridge but with slow startup and increased voltage drop.

If that is the case then the schematic is ok.
Mona

 

[sumotan]

Thanks Gent now if trafo winding is 350v & with voltage drop etc, how is the ouput able to reach 380v ?
Also if I were to build this psu & use other then Lundhal trafo , is the hv suppose to be 175-0-175 or ?

Thank you again

 

[euro21]

The peek of bridge rectifier is 350V*√2 minus rectifier tube dropout (at desired current).... ideally (depends of power transformer secondary DCR).
Estimated -ideal- voltage on first capacitor:
350V*√2 - 15..20V ... about 475...480V.

The serial connected chokes DCR is 2*36Ohm.
If each channel current is 100mA, there 72R*0.1A= 7.2V drop.

If you want exactly 385V, must to decrease first capacitor value (even to few uF).

 

[sumotan]

Thanks Euro 21. So for this hybrid stage Ac to Dc is using SS formula for conversation then. Re trafo if I use another trafo does this mean 175-175 or 175-0-175 ?

Thks again