Modified Sine Wave Inverters

[John Dunkley]

What electronic equipment is it NOT recommended to run off of modified sine
wave inverters?

Appreciate some advice on this.

JD

 

[John Beardmore]

What electronic equipment is it NOT recommended to run off of modified sine
wave inverters?

Audio mixing desks. Buzz like buggery !


Cheers, J/.

 

[John Beardmore]

Poor power supply, grounding and sheilding techniques.

Doubt it. Exactly the same grounding and shielding techniques worked
fine with a sine wave inverter dropped in as a replacement.

As to the power supply being poor, (presumably you mean in the
mixer ?), it's certainly true that it's not designed or sold to cope
with non sinusoid power supplies.

Does using a non sinusoid inverter make it a poor power supply, or is it
a poor choice of power source ?


J/.

 

[John Beardmore]

Poor power supply. If you out it
??


on a DC supply it won't buzz either.

If you mean run the mixer power supply from DC, the transformer won't
last too long...

If you mean that the mixer electronics could be run off a DC supply, I'm
sure you're right, but

a) that doesn't help if you want to use a non sinusoid AC supply,

and

b) the noise may not be coming through the power supply anyway.

I put my two year old on the street were there were no cars and he
never got hurt.

I put my banana up a tree and it didn't rain.

It must be the cars that cause children to get hit.

Maybe ethylene promotes fruit senescence ?

Component qualities are rated, partially, by their noise rejection of
power supply inputs and grounding etc..

Well yes. You might specify a preamplifiers rejection of supply noise.

But I fail to see how that makes operating a power supply outside its
design envelope the fault of the power supply - indeed in this
instance, there is no reason to assume that the noise that makes it to
the output of the mixed even comes via the mixer PSU.

All we actually know is that it wasn't a problem with a sine wave
inverter, but it was with a non sine wave inverter.

The OP wanted to know "What electronic equipment is it NOT recommended
to run off of modified sine wave inverters?". On the basis of my
experience in the field, I'm nominating audio equipment, because it can
be a problem, at least some times. You can talk about your children if
you want.


J/.

 

[You]

What electronic equipment is it NOT recommended to run off of modified sine
wave inverters?

Appreciate some advice on this.

JD

Laser Printers.......

 

[John Beardmore]

LOL. No, the children was analogy of what you stated, in a attempt to
clarify the poor logical association you made between noise and MSW
PS.

Well, can't say it does it for me, and I'm not sure the association was
poor.

I am sure the amplifier/mixer is designed to reject noise fairly well.
The point is that the MSW is only a factor, in your case, most likely
because of poor grounding, sheilding or equipment design.

Well, I didn't put the system together so I'm not sure I had much
'ownership' of the configuration.

None the less, unless you are referring to the grounding, shielding or
equipment design of the inverter itself, there was no difference between
the wiring for the sine and MSW inverters.

This is not
totally the fault of the inverter waveform.

Indeed. It could be down to the grounding, shielding or equipment
design of the inverter itself. Do you think the inverter manufacturers
frequently get this stuff wrong ?

Of course, this is within
reason too. Most equipment aren't gonna' take a square wave PS without
getting hot, or buzzing.

Well, obviously quite a lot manages it in practice.

I am suggesting you look at your signal input grounding for picking up
some noise in the grounding conductors from the dirty inverter.
Usually multiple grounding points are the problem where some power is
being carried or induced into a signal ground.

These were audio systems put together as part of festival sound stages.

It's entirely possible that if plugged together in some less than
obvious way, the grounding could have been improved.

None the less, the upshot is that the use of a non-sinusoid supply may
be more problematic.

MSW may not be a
problem for the unit at all if clean techniques are used.

Indeed. Back in the real world...

Upshot remains that non sinusoid supplies may cause more problems with
audio equipment.

Good luck
finding it though...LOL

It was nearly four years ago. Don't think I'll be trying to rework the
signal paths and grounding. Didn't need to anyway as we just used a
1960s sine wave inverter instead.


Cheers, J/.

 

[sonny Power]

Hi JD,
I've been using a Trace DR1524 modified sine wave inverter for about 8
years. I have yet to find something it won't run. It runs computers, TV,
satellite modems, Cisco router, fridges, etc.
Floyd
http://survivaldealer.com
http://witchwellenergy.com

 

[CampinGazz]

Hi JD,
I've been using a Trace DR1524 modified sine wave inverter for about 8
years. I have yet to find something it won't run. It runs computers, TV,
satellite modems, Cisco router, fridges, etc.

i've got something that wont run on it... the washing machine in my
motorhome, refuses to start up on a msw inverter output and the circuit
board gets hot,

put a pure sine wave inverter on it, and it works exactly the same as it did
on shore power, it's coz of the fuzzy logic crap in modern washers, warying
hte water levels according to the load, farting about distributing the
clothes evenly before doing a high speed spin etc.

seems to be owt that uses a thyristor in the design dosent like msw inverter
outputs,

At the moment i keep my msw inverter (antares 1600 soft start.. and old un
with a big torodial transformer in it, bullet proof) as it runs the
microwave (mechanical timer) central vacuum system, hair dryer, bug zapper,
fans, inkjet printer, laminator etc fine, little more buzzing on the
microwave but that's to be expected as a transformer expects a nice pure
sine wave, so the abrubt chopping of a msw will create a bizz)

The pure sine wave inverter just powers the washing machine (Candy aqua
1000T, one of those compact washers, like a home model but a 3.5 kilo load
capacity instead of the usual 6 or 7)
when i get round to it i'll be replacing the main antares and washer
inverter with a single 1500 watt pure sine wave inverter, just because i can
get a decent one for about £200 from a bloke i trust and knows what he's
talking about with inverters.

 

[Blue Cat]

i've got something that wont run on it... the washing machine in my
motorhome, refuses to start up on a msw inverter output and the circuit
board gets hot,

About 10 years ago (before sine wave inverters were inexpensive) I did some
experimenting with motors and square wace inverters. I found that if you
connect a capacitor in parallel with a motor load, you will improve the
power factor and also the probability that a motor load will start properly.
Capacitance depends on the current drawn by the motor at rated speed. Such a
capacitor must be capable of functioning in ac power.

I assume that if this works with square wave, it will also work with
modified sine wave.