Justin & Jerry's Hifi Blog

[montesquieu]

Just wire in series 110v + 110v = 220v

As all board voltages appear to be regulated there is no need for a step down device.

It's really only needed when you have ac heaters etc...

Happy Days

Hi Duncan, for the technically challenged, can you elaborate?

Are you saying it doesn't matter that the mains transformer is 220v, because the secondaries are regulated? How does that work?

[User211]

Are you saying it doesn't matter that the mains transformer is 220v, because the secondaries are regulated? How does that work?

I think he is, didn't read what he said earlier and deleted a post as a consequence. Let's see...

[tubehunter]

For example a L7806CV Linear Voltage Regulator

This device will accept a voltage range of 11v to 35v input for a 6v 1.5A output.

Problem is, as the input voltage rises the device will get warmer and will need a heat sink.
Also the rectifier diodes require 0.6v.

So ideally the input needs to be about 3 or 4 volts higher than the required output voltage.

The secondary windings on the pictured transformer show voltages 2x15v, 8v, 7v and another I can't make out.

So adding 10% gives 2x16.5v, 8.8v and 7.7v, I'm pretty sure the voltage regs' can handle that.

Happy Days

[montesquieu]

For example a L7806CV Linear Voltage Regulator

This device will accept a voltage range of 11v to 35v input for a 6v 1.5A output.

Problem is, as the input voltage rises the device will get warmer and will need a heat sink.
Also the rectifier diodes require 0.6v.

So ideally the input needs to be about 3 or 4 volts higher than the required output voltage.

The secondary windings on the pictured transformer show voltages 2x15v, 8v, 7v and another I can't make out.

So adding 10% gives 2x16.5v, 8.8v and 7.7v, I'm pretty sure the voltage regs' can handle that.

Happy Days

Thanks Duncan that's helpful.

And no issues with the mains transformer itself running potentially 20% above specified voltage?

[tubehunter]

It’s closer to 10%

220 + 22 = 242

So not really, no

[brian2957]

Thanks for the clarification Duncan

[montesquieu]

It’s closer to 10%

220 + 22 = 242

So not really, no

I made worst case possible voltage (obviously without a regenerator) as 240v + 24 = 264.

[User211]

I made worst case possible voltage (obviously without a regenerator) as 240v + 24 = 264.

From Wiki:

"In the UK and Australia the nominal supply voltage is 230V +10%/−6% to accommodate the fact that most supplies are in fact still 240V."

So 253V max if in spec. My regen says mine is 246V.