Can the below be done safely? I have two circuits running 2 different sources.. space is limited and if I can get away with using a single ground that would be fantastic.
+120VAC-----------------|+ AC -----------------| LOAD | GND------| | -----------------|-DC +12VDC-------------------|+ LOAD
Not unless ya got a death wish !! Your diagram is not clear though, surely you are not using active to ground for the AC part ??
-- Cheers ......... Rheilly P Where theres a will, I want to be in it.
Here is clarification for you on what i'm actually doing. I have a cold cathode light that runs off 120VAC, i have a inverter that converts 12VDC to the neccessary 120VAC.. i have an series of LED's that need DC.. so i was thinking of running the positive line for the DC power to the LED's then just hook the ground of the LED segment to the same ground as the return to the inverter.
no. use a fixed-pitch font for posting ascii diagrams.
I'm guessing what you were trying to draw here.
I don't think connecting an AC load between live and ground is a good idea
if your 12V load is well insulated (as well insulated as the live parts) you cpould substitute neutral for GND.
-- Bye. Jasen
Ok I get it. I would not be comfortable with relying on the integrity of the ground since if there is any failure in that connection ya gonna end up with a handful of volts on the leds, perhaps you could use some of the modern thin insulation cable available and keep the circuits isolated ?
-- Cheers ......... Rheilly P Where theres a will, I want to be in it.
Electrically it'll probably work (if the inverter has an isolated output) but it's quite possibly unsafe. where is this being installed?
-- Bye. Jasen
What if i put a zener diode on the line heading towards ground from the LED cirucit? so if there is a short and voltage gets applied to ground, then the zener should blow preventing power from getting to the LED's.
well i'm building a model of the StarTrek Enterprise-D, and i'm modifying they model to provide lighting. The cold cathodes would be usedto light up the nacelles, with 2 red led's to light the front of the nacelles. the problem is i need to run as few cables as possible to prevent marring of the outside appearance of the pylons(the section that connects the main body to the nacelles. i'm hoping to get away with just 3 wires.. 2 wires that come from the invertor to the cold cathode tube.. and 1 positive going to the LED's. i'm hoping i could just ground the 12V led's to the wire that returns to the inverter from the cathode tube.
Beware that many small 120V inverters DO NOT have a grounded neutral - both AC lines are "hot". If your inverter is like this, your circuits won't work - it will apply 120V to your 12V LEDs.
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that's not a good idea. if you should lose the ground you would end up getting 120Vac into your circuit of 12 volts. and even if you didn't lose the ground, on days of thunder of near by hits you could intermitly lose the effective ground depending on your soil etc. and still end up with 120 getting into the dc.. basically, its not a good idea.
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why not use a neon instead of an LED and run it all on 120V.
OTOH extremely thin wires can be used to power LEDs.
Bye. Jasen
On Sun, 18 Jun 2006 15:05:49 GMT, in message , "none none" scribed:
OK, your idea now appears quite different than originally presented. The "ground" that you want to use (as another poster wondered) is not ground at all, but merely one side of the AC supply. Since you haven't presented the source side of the circuit - where the 120vac and the 12vdc originate - then you might have a really poor design in the works here. It might smoke as soon as you plug it in, aside from the concerns about losing the connection to ground, which apparently does not actually exist in the design.
If, as it appears, you are using a 12vdc source to power both the LED's and a small inverter for the 120vac, then your idea is unworkable. The output side of the inverter will not be referenced to ground, nor probably should it be grounded by the designer, without careful consideration of the consequences. Seeing that the ground in this case would wrap back to the
12vdc input, I can't help but think it's a terrible idea. Use the poster's suggestion about thin wires for the LED's, and use two wires for each circuit.ElectronDepot website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.