Relay switching grounding

[Jennings]

I’m toying with some relay-driven channel switching for the first time. Where/how do I best ground the relay circuit? Well away from circuit ground points, I presume?

[TIMBO]

Yes

[glass54]

+1 with Timbo 
DO NOT earth your relays if using heater generated PS!!
See Doug's very useful pages:
https://el34world.com/projects/relay_switch.htm
Regards
Mirek

[tubenit]

There is a lengthy thread loaded with great information about relays in ARCHIVES!


Relay circuit & layout board & ft switch


With respect, Tubenit

[Jennings]

Thanks folks...great info on those pages.  I was planning on using the heater supply for the relay power supply also.  The transformer I'm using has a centre tap available on the 6.3V winding.  So if I'm understanding correctly the relay circuit "common" points just tie together as in the attached schematic?

[Merlin]

You can't have a ground on both sides of the rectifier or it will be shorted out.
So either you ground the transformer centre tap and let the relay circuit float (in which case you need an insulated footswitch jack, and don't connect the footswitch enclosure to the anything), which is what your diagram seems to show so that's good.
Or you ground your footswitch circuit and disconnect the transformer centre tap, which might not be great for heater hum.

Btw you don't really need a regulator, a simple resistor before the 4700uF cap will do.

[Jennings]

Thanks Merlin for the info and confirmation I’m on the right track. I didn’t think to use a resistor! I haven’t wired this up yet (although the relay tagboard is already made up), but as there’s a centre tap on the heater secondary I’ll use that and keep the relay power supply floating as per the diagram. I was planning on using isolated Cliff style jacks for the footswitch. Although I’m half tempted to add LEDs…in which case I might need a DIN / multi pin style instead.