groundingpower
I am nearing the completion of my DIY compressor project, and I have a rather seemingly basic question..
Once I hook up my toroid and everything, since I don't have my 19" 1U rack enclosure yet, but would like to test my projects for any problems, is it safe enough to find a metal piece somewhere, put a lug, and attach all my grounding to it?
I should also add that the compressor is the GSSL project and is all solid state design. No tubes.
Better filter caps?
It's not always the power supply. Grounding can be a common problem in these kinds of units, ground loops in particular.
If the following circuit is representative of your power supply...
(source: circuit-projects.com)
...C1 and C2 are the filter caps. You can try increasing the values of those to reduce the hum. They are typically electrolytics. If your power supply doesn't have voltage regulators like this circuit does, adding voltage regulators should lower the hum considerably, if it's not a ground loop.
I see several details in your drawings.
1) The top drawing is of a shielded power cable, and the power can be AC or DC.
2) Pin 'E' on the J2 connector is Earth ground for the chassis and power. The J2 connector has a gnd symbol at the bottom to clarify it is earth grounded.
3) J2 also shows built-in capacitors to filter out EMI noise from either direction. I would use pin 'E' as power ground even if you just run a green wire to your power source ground.
4) The dashed lines around J2 refer to the chassis in an abstract way, and show it is grounded to J2 and J3 connector shells directly.
5) There maybe other drawings that tie into these drawings, but for power source and ground these seem to cover the issues.
6) The power cable does not have to be shielded for non-military use. Make sure J2 is wired correctly for the voltage you are using, AC or DC.
Best Answer
Have exposed mains is dangerous, and I expect you know that. This answer only talks about how to do it, not if you should do it!
That being said...
You do want to bring all of your grounds together. This can be to any piece of random metal that you can firmly connect them to. If you had ring terminals, I could envision each ground wire being terminated with a ring terminal, and all the ring terminals connected around a bolt with a washer and nut.
Don't forget to hook up this big node of wires up to the ground wire in your mains! It doesn't do any good if it's floating. And, of course, make sure it can't make accidental contact with the live circuitry.
Also, for a project like this, I always try to plug it into a GFCI outlet. If you don't have one available, you can find an extension cord with an integrated GFCI. This way, it ensures that your ground node won't get "hot", in case anything goes wrong...
Good luck :)