Power supply when mains voltage in unstable

[hajj]

I just scored a pair of populated F5 boards, and am in the process of building the power supply for the amp (much more complicated than the amp boards themselves!! ah the pleasures of DIY)

Over here in Lebanon, it is not uncommon to have the mains voltage fluctuate between 220 and 209 volts (and in extreme cases, down to 200V).
The F5 PS as per the F5 manual not being regulated, I was wondering what the effect would be on the amps performance and durability, and If there would be a need for a voltage regulator stage.

In case it should matter, I will be using a 1000 VA EI core transformer (custom wound, still cheaper than toroids over here) and will most probably have around 176,000 uf of capacitors.

Thanks

Nick

 

[basite]

Does it ever rise above 220V? As you're getting it custom wound, it might be an option to wind them for a 210V or 215V "net" voltage. That might average out the differences. (little more, little less)

Rail voltage on the PASS F5 isn't very high (25V or so?) which would make the difference after the tranny something like 22,5V when it's 200V, and 25V when "normal"
getting the custom tranny, you could go for something like 24V to 26V? theoretically.

I don't think that would be a major problem. Still has to be rectified etc...

Regards,
Bert.

 

[KMossman]

or use an AVR or/and UPS

 

[hajj]

or use an AVR or/and UPS

There are also economical constraints, and a decent AVR or UPS will cost me more than the whole amp, this is why I though about a good regulator stage.

@Bert,
I like the solution you proposed, I'll try to get the guy to modify the secondaries to yield a higher voltage, and take it from there.

Thanks for your input guys, keep them coming

Regards

Nick

 

[FoMoCo]

Keep in mind that even 200 volts is only a 10% change. You may not need to do anything.

You could also use a small 220 to 12 center-tapped transformer in series to boost the line voltage by 6 or 12 volts, as needed.

 

[hajj]

You could also use a small 220 to 12 center-tapped transformer in series to boost the line voltage by 6 or 12 volts, as needed.

Could you elaborate please?
I'm trying to figure out how this might work (how to set it up), but being low on caffeine doesn't help.
Thanks

 

[simon7000]

See if you can get taps for 200, 210 and 220 on the input. Then it is very easy to use a switch and a meter to set it up. First switch position should be 220. An automatic switch is a bit harder but not much.

 

[AndrewT]

200 to 220 is only +-5%, as pointed out by Fo.
The normal range is +-6% and in Europe it is now +10% -6%

If your range is ONLY 20Vac then you have probably not measured the extremes of the allowable tolerance.