Rectify 6.3 AC to 5 DC and grounding

[sbirkenstock]

Hi Everybody,

I am rectifying the 6.3V filament to 5V DC in order to switch 5V relays.
I´m using a FBR with four 1N4007 (resulting in 8.3V) and a 5V voltage regulator.
Works fine, but I am insecure about the grounding.
My rectifier + relay test board is currently not grounded at all.

I found some articles talking about taking the center tap of the filament off.
My filament currently is grounded with two 100 Ohm resistors.
I do not understand what the difference might be concerning the rectifier.

Also, can I (additonally) ground the minus side of the filter cap following the FBR?

thanks in advance,
Stephan

[martin manning]

I would remove the 2x 100R and ground only the negative side of the relay supply (the bridge and the filter). Your heater string will then be elevated ~3.15V. If you leave the 2x 100R to ground you will have that 3.15V pushing a current from the relay supply ground to the CT ground.