Harold Barber
Member
GROUNDING OF PRO AUDIO: I saw your video on Understanding Grounding in Audio, very good one and I read Bill Whitlock´s article. I understand the principle of the electricity going back to the transformer to complete the circuit and "Not to earth"... BUT that is under ideal circumstances, as a live sound engineer I´ve had many situations with electric sources without a grounding terminal (I live in Venezuela) (By the way we have the same grounding system as the US) and I´ve had audio ground problems, sometimes a little hum, sometimes electricity on your lips when you touch the microphone and I´ve solved it by "creating a ground" connecting a wire from the chassis of the mixer to a water pipe, a metal fence or even just sticking a screwdriver yo the ground. I know that probably it won´t provide a safety path in case of a electric short circuit but it does get rid of the AUDIO grounding problems. It seems that SOME noise CAN be drained to earth.
Also in your video there is your explanation of a circuit using a battery an a light bulb is clear BUT what happens if instead of the positive of a battery you use the hot terminal of a 120v AC receptacle and instead of the little bulb you use those voltage detector screwdriver, not the plastic voltage sniffer but the old type with metal tip and you touch the metal plate on the handle and the neon bulb turns on. How is the circuit completed? I even tried it (just for kicks) with my Nike shoes on a plastic chair on a wooden floor and the bulb lights.
My only explanation is that our body mass is capable of absorbing some electrons, enough to light the little current needed by the neon bulb.
The same way the Earth is capable of absorbing the little parasitic current that causes the hum and lip voltage in the first example.
If we accept that Earth is at 0 volts and we have some voltage on the green wire it seems logic that when connecting them together the voltage will drain to earth.
Also in your video there is your explanation of a circuit using a battery an a light bulb is clear BUT what happens if instead of the positive of a battery you use the hot terminal of a 120v AC receptacle and instead of the little bulb you use those voltage detector screwdriver, not the plastic voltage sniffer but the old type with metal tip and you touch the metal plate on the handle and the neon bulb turns on. How is the circuit completed? I even tried it (just for kicks) with my Nike shoes on a plastic chair on a wooden floor and the bulb lights.
My only explanation is that our body mass is capable of absorbing some electrons, enough to light the little current needed by the neon bulb.
The same way the Earth is capable of absorbing the little parasitic current that causes the hum and lip voltage in the first example.
If we accept that Earth is at 0 volts and we have some voltage on the green wire it seems logic that when connecting them together the voltage will drain to earth.