[chbot] Robotics Group meeting, Monday 19 Nov 2018, 630pm, 5 Idris Road

[Mark Atherton]

I have seen that schematic before, however the implementation as an 
Arduino Nano shield looks like a death trap to me.

Not happy with using standard SMD resistors on the live side unless they 
were designed for the job (like MELF).

Vishay SFR25 thro-hole resistors are rated to 250VAC each, so one on 
each side of the bridge would be a good idea.

Would like to see an opto with at least 1kV AC isolation. Also enough 
PCB room to allow for a decent isolation gap.

One failure mechanism is for the mains cable to pull off the shield, 
then the whole live assembly is rattling around. Allowing plenty of room 
to allow the board to be properly secured using screw fasteners to a 
grounded plate could fix this issue.

http://www.magazines007.com/pdf/High-Voltage-PCDesign.pdf seems to be 
quite interesting and relevant.

If in doubt, big, wide and stupid :)

-Mark


On 19/11/2018 10:26 PM, Volker Kuhlmann wrote:
> The zero-crossing detector circuit I mentioned is here:
> https://www.circuitar.com/nanoshields/modules/zero-cross/
>
> Scroll down to the schematic link, which is a complete article
> describing the circuit.
>
>
> Mark could you post the opto isolator details please?? Ta.
>
> Volker
>
>