On Wed, 22 Mar 2006 23:10:43 +0200, in comp.arch.embedded Paul
Keinanen <keinanen@sci.fi> wrote:

>On 22 Mar 2006 10:04:33 -0800, "Zenty" <div@ramsdal.dk> wrote:
>
>>Hi!
>>
>>Can anyone tell me what is needed to change the design of Microchip's
>>light dimmer (called PICREF-4) to use 220V instead of 120V?
>>
>>http://ww1.microchip.com/downloads/en/appnotes/40171a.pdf
>>
>>Its no problem to change the program for the PIC12c508 - but I need the
>>circuit to work with 220v @ 50Hz.
>
>If you really have to ask that, I would suggest that you think twice,
>before starting this project, since there is a real risk that you
>might kill yourself or even worse, some of your friends.
>
>I would suggest using an isolation transformer (230:230 V) for the
>tests.
>
>You should be aware about the creepage distances in PCB design.
>
>The voltage ratings for capacitors should be obvious, but the voltage
>ratings for various high ohmic resistors should be carefully examined.
>Although a single resistor might handle the required power
>dissipation, the 1-10 Mohm resistors might need to be implemented with
>several resistors in series to get the required voltage handling.
>
>Paul
I'd put the varistor after the 47R, so it doesnt have to short out the
power station on spikes, same with the 20MegR. I would not use a 20M
anyway, but an attenuator, say/guess 220K and 5k to ground (YMMV).

A couple of other replies in SED, as well


martin

On 22 Mar 2006 10:04:33 -0800, "Zenty" <div@ramsdal.dk> wrote:

>Hi!
>
>Can anyone tell me what is needed to change the design of Microchip's
>light dimmer (called PICREF-4) to use 220V instead of 120V?
>
>http://ww1.microchip.com/downloads/en/appnotes/40171a.pdf
>
>Its no problem to change the program for the PIC12c508 - but I need the
>circuit to work with 220v @ 50Hz.

If you really have to ask that, I would suggest that you think twice,
before starting this project, since there is a real risk that you
might kill yourself or even worse, some of your friends.

I would suggest using an isolation transformer (230:230 V) for the
tests.

You should be aware about the creepage distances in PCB design.

The voltage ratings for capacitors should be obvious, but the voltage
ratings for various high ohmic resistors should be carefully examined.
Although a single resistor might handle the required power
dissipation, the 1-10 Mohm resistors might need to be implemented with
several resistors in series to get the required voltage handling.

Paul

Hi!

Can anyone tell me what is needed to change the design of Microchip's
light dimmer (called PICREF-4) to use 220V instead of 120V?

http://ww1.microchip.com/downloads/en/appnotes/40171a.pdf

Its no problem to change the program for the PIC12c508 - but I need the
circuit to work with 220v @ 50Hz.

I really hope someone can help me.

Thanks in advance!

Best aRegards
Zenty