What do I need to modify to run Zenv4 off lesser voltage?

[DrewP]

Folks, because my DIYing runs pretty slowly (and I fried my original Zen revisited) I'm in a bit of a bind.

I have a lovely 500 watt C core tranny with twin 25vAC outputs, the rectifiers and a nice 30,000uF/3mH/30,000uF pi filter built plus some big *** heatsinks ready to go.

Problem is that Zen has come along way since the "revisited" and the Zv4 wants about 50 volts.

Is there any way to configure the cct so it runs off the same rails as the original? I've got alot of dollars tied up in this PSU and want to get this project finished and making sweet music (soon would be nice).

If I could just get the boards from Nelson, make a couple of component value changes and be done that'd be marvellous.

But is it possible?

All advice and help gratefully accepted

Drew

[till]

2*25*1.4 makes about 70Volt. Why not use irfp140 or 240 instead of 044 and build a 70 Volts ZV4 .

Or just burn the Voltage you think is too much in the regulator Q5. Use a big heatsink for Q5 and vary the zehners for the desired voltage.

[DrewP]

Umm, the plan was to use each output for a separate channel. 34 v for each side.

I'm just throwing away current capacity and channel separation if I use the rails in series.

Yes it'd work but is there a more elegant solution droppping the required voltage of the cct down a little?

drew

[till]

leave away the regulator of V3, build V2 with input buffer from V4, and live with less output power. You don´t really need the regulator, V2 workes quiet well without it, and it wastes voltage.

[jh6you]

I am fully with till.

If you however want ZV4, I would do as follows:

(a) Check if the unregulated voltage is around 34V per each channel.
(b) Change Z1-Z5 to get the total zener voltage of about 31V.
(c) You will see regulated voltage of about 27.
(d) Change R 13 with 2.7K.
(e) Adjust R4 to get 15V at the point between R5 and R14.

You will have ZV4 of a less output power.

[Nelson Pass]

Put some inductance in series with the primary of the
transformer. It will lower the voltage without additional
dissipation and also improve the power factor out of the
wall.

[jh6you]

[Nelson Pass]

[DrewP]

What's the deal with inductance before the tranny? I want more volts from the PSU not less or else I want the cct to require less to run.

Unless, of course you're talking about using both sides in series again and not having channel separation in the psu. From preference I'd rather keep the 2 channel supply if possible.

Seems like the first post by jh6you gives me a method by which i can do this on the supplied cct boards.

Many thanks

Drew

[billy]

Originally posted by till
2*25*1.4 makes about 70Volt. Why not use irfp140 or 240 instead of 044 and build a 70 Volts ZV4 .

Or just burn the Voltage you think is too much in the regulator Q5. Use a big heatsink for Q5 and vary the zehners for the desired voltage.

If i use 70Volt , i just change Q1, Q2 , Q5 to IRFP250 or IRFP150 is okey? no need to charge other ?

Thanks!!