Primary (mains) side ground symbols

[japlytic]

In circuits I create with a CAD program, I use a "named ground" (a plain downwards pointing triangle labelled "0V") for any common return on the mains side (0V - typically the -ve of the main filter capacitor).
Some commercial circuits may use a "chassis ground" or even a regular ground symbol .
When "named ground" symbols are used (e.g. 0V), it is easy to tell if a ground or common connection is at mains potential.

[kaboom]

Re: Primary (mains) side ground symbols

Yes! Never ASSume anything about grounds based only on what symbol they have. Unless you want a Billy Mays 'Kaboom' moment.

Look at that 'ground' off the negative side of the bridge rect in the sch. Same as the EGC symbol- assumed to be zero volts. Not only is it not zero WRT ground, it's floating because of the bridge. No scope grounds here, you'll short the line out thru half of the rectifier!

They use the chassis ground 'fork' symbol for the secondary/signal grounds. At one time, that was the same symbol for 'ground' in the old AA5s! Yea right, depending on which way the plug was and the filament string...

Watch it there. Name enough separate paths, and someone will scream, "The triangles all look the same- what numbers?"

-Paul