12 V and mains Inverters...

Hi,

I am new here and would like to say hi to everyone here. Some fantastic rigs and great looking works in progress. I will be launching a new website soon and will post up some of my own pics.

I want to start a discussion on inverters. They are often nasty things in terms of contributing noise to a system and I have found this especialy true when using portable systems with dubious or nonexistant ground connections.

I have taken to using an earth spike (rod of metal with a good electrical connection to a length of decent cable), attached to the ground connection on my rigs. It's yet another bit of kit (weight) to carry around, but of great importance when using 12V - 240 V inverters to run laptops, decks etc.

What are people's experiences with inverters? there are a wide range out there and the efficiency ranges from sub 50% to well into the 90's. Price also obviously roughly corrolates.

It's often the case in my experience that only a small amount of power is needed at 240 v if the rest of the setup is well managed, so are there any good tips on fairly moderate power full sinewave inverters for good prices?

What are people's expereince with mains hum reduction (when using nverters) and noise reduction generally with portable rigs?

J

BrightonJake wrote: Hi, What are people's experiences with inverters? there are a wide range out there and the efficiency ranges from sub 50% to well into the 90's. Price also obviously roughly corrolates.

Well I've actually successfully used a cheapy 350W "modified" (yeah, it ain't arf modified - had it on the scope at my mates place - basically a square wave with a bit of holes and spikes) ..... but it works quite OK with just a decent quality hi-fi amplifier (oldish Pioneer class AB 50W + 50W thing) .... reasonable run-times with a 45Ah car battery. No earth loop or other noise problems ...... that was in conjunction with a mixer run directly from the 12V DC.

The only thing that concerned me a bit when I first tried it was a slightly "different" "buzz" from the amplifier's transformer - but its never actually caused a problem. This could be just luck of course :-)
I'd guess the 230V drain would be _much_ less than its rated 350W ..... never tried it with something a bit more demanding 230V-wise ....

infrasound wrote: whats the difference in efficiency between pure sine and modified sine wave inverters? Does the difference in circuitry used between the two give drastically different efficiencies?

Couldn't tell you mate .... google should be your friend with this .... but I'd _guess_ that if anything the pure sine wave ones would be _less_ efficient, as the circuitry that shapes the output will probably be throwing away some power as heat .... OTOH the _overall_ effiency might be similar or better, as e.g. an amplifier's transformer/rectifier might chuck out extra heat with a "modified" power input.

Jake ... i would go for a well branded make .. Mastervolt , Victron, Xantrex & Waeco .. have fitted hundreds of these and the real cheap nasties which i would never use .. i use 2 Mastervolt 4000w combi inverter on my boat .. in that game .. you really do get what you pay for .. you can pick these up 2nd hand on ebay .. so you wont be paying top dollar .. a 2nd hand branded one will be far better than any brand new chinese knock off .. the amount of them that i have seen catch fire/ burn out laptop charger s etc is beyond belief

bought a one metre ground spike in screwfix, cut it in half, fits easily in a box where i carry my cables.
had a good amount of hum reduced when using it.