Homebrew_PCBs

> I am currently designing a 10-300V, 100mA bench PSU. The transformer is a
> 300-0-300 from an old valve power amplifier.
>
> What is the minumum track spacing I can use for 300V AC and the resulting
> 420V DC?
>
> --
> Stuart Winsor
>
> Tools With A Mission
> sending tools across the world
> http://www.twam.co.uk/
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> Posted by: lists <Stuartlists@...>
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> Depends on a number of factors such as expected pollution, humidity,
> operating altitude, etc.

> Something under 0.5mm will possibly result in immediate failure.
> Something like 1mm would probably be my design minimum.

> Obviously this is functional insulation only, in other words if this
> insulation breaks down nothing bad must happen except a blown fuse.
> For any kind of safety insulation you would need much more than that.

On Feb 4, 2015, at 8:57 AM, lists Stuartlists@... [Homebrew_PCBs] <Homebrew_PCBs@yahoogroups.com> wrote:

In article
<CAMmT-dZ57vncGCgRHDD29pyeAYmBVdzfeGtpKwEnCbW1147aqA@...>,
Stefan Trethan stefan_trethan@... [Homebrew_PCBs]
<Homebrew_PCBs@yahoogroups.com> wrote:
> Depends on a number of factors such as expected pollution, humidity,
> operating altitude, etc.

> Something under 0.5mm will possibly result in immediate failure.
> Something like 1mm would probably be my design minimum.

> Obviously this is functional insulation only, in other words if this
> insulation breaks down nothing bad must happen except a blown fuse.
> For any kind of safety insulation you would need much more than that.

Thanks. I noted that the 2u2 450V* capacitors I bought had a 0.2" pin
spacing and I would have thought more than this would be required. I have
adopted a 0.2" minimum pitch for the tracks and the 0.1" dia pads for the
capacitor means a minimum of 0.1" or 2.5mm between them.

* Input capacitors are a pair of 100uF 250V in series with 330k voltage
equalising resistors.

-- 
Stuart Winsor

Tools With A Mission
sending tools across the world
http://www.twam.co.uk/