# Square to Sine Wave

W

#### west

Jan 1, 1970
0
I have an inverter that puts out a nice 120v square wave. The inverters that
put out a pure sine wave are expensive. Does anyone know where I can obtain
schematics to build a square to sine wave converter fo my inverter? Thanks
Cordially,
west

L

#### Luhan

Jan 1, 1970
0
west said:
I have an inverter that puts out a nice 120v square wave. The inverters that
put out a pure sine wave are expensive. Does anyone know where I can obtain
schematics to build a square to sine wave converter fo my inverter? Thanks
Cordially,
west

You can't get there from here.

Luhan

J

Jan 1, 1970
0
west said:
I have an inverter that puts out a nice 120v square wave. The inverters
that
put out a pure sine wave are expensive. Does anyone know where I can
obtain
schematics to build a square to sine wave converter fo my inverter?

If you have a somewhat fixed load at lowish (<100W or so) power levels, you
can use a rather large inductor and capacitor to build a low-pass filter and
knock down the non-60Hz (or 50Hz) harmonics. Add more inductors and
capacitors to make the result as sine-ish as you're willing to pay for...

In the general case of high power/widely varying loads, this approach
quickly becomes more expensive than just buying a sine wave converter in the
first place and hence isn't practical... unless you're looking for an
educational in winding your own high power inductors, which actually is
rather fun...

T

#### The Phantom

Jan 1, 1970
0
I have an inverter that puts out a nice 120v square wave. The inverters that
put out a pure sine wave are expensive. Does anyone know where I can obtain
schematics to build a square to sine wave converter fo my inverter? Thanks
Cordially,
west
As a matter of curiosity, if a device (black box) were available to connect to
the output of your inverter and provide a sine wave from the inverter's square
wave, what would you be willing to pay for it? And how much power are we

P

#### [email protected]

Jan 1, 1970
0
west said:
I have an inverter that puts out a nice 120v square wave. The inverters that
put out a pure sine wave are expensive. Does anyone know where I can obtain
schematics to build a square to sine wave converter fo my inverter? Thanks
Cordially,
west

I read that series resonant converters are good for upto 20 kW at epanorama.
But they are intended for the dc/ac conversion not as an after the
fact solution.

F

#### Fred Bloggs

Jan 1, 1970
0
I have an inverter that puts out a nice 120v square wave. The inverters that
put out a pure sine wave are expensive. Does anyone know where I can obtain
schematics to build a square to sine wave converter fo my inverter? Thanks

Anything at all can be done by finding the right schematic? Make sure it
contains a transformer because by the time you attenuate all the high
frequency components, your output will be at brown-out level.

J

#### J.A. Legris

Jan 1, 1970
0
Fred said:
Anything at all can be done by finding the right schematic? Make sure it
contains a transformer because by the time you attenuate all the high
frequency components, your output will be at brown-out level.

T

#### Tim Williams

Jan 1, 1970
0
Luhan said:
You can't get there from here.

Poppycock. A steep (couple pole) low-pass filter will do it.

Delivering a reasonable amount of power through it, at a variety of loads
and power factors, and having the inverter appreciate it, is another story
completely. ;-)

Tim

K

#### Ken Smith

Jan 1, 1970
0
Poppycock. A steep (couple pole) low-pass filter will do it.

Delivering a reasonable amount of power through it, at a variety of loads
and power factors, and having the inverter appreciate it, is another story
completely. ;-)

If the filter is steep because of notches and the notches are at the odd
harmonics, and implemented buy parallel tuned circuits, it may not be so

Prehaps more stages
!
180Hz 300Hz V
! ! ! ! !
----!!-----+----!!----- --- )
--- )
! )
GND !
GND

It works at higher frequencies.

By time you pay for the extra parts, a sine wave inverter may look better.

K

#### Ken Smith

Jan 1, 1970
0
Anything at all can be done by finding the right schematic? Make sure it
contains a transformer because by the time you attenuate all the high
frequency components, your output will be at brown-out level.

XL = 1
!
---
--- XC = 1
!
GND

If you try to unplug the load, the connector will flash over.

L

#### Luhan

Jan 1, 1970
0
west said:
I have an inverter that puts out a nice 120v square wave. The inverters that
put out a pure sine wave are expensive. Does anyone know where I can obtain
schematics to build a square to sine wave converter fo my inverter? Thanks
Cordially,
west

I believe my original post was essentially correct. Commercial sine
wave inverters use variable pulse width modulation to closely
approximate a sinewave. A minimul amount of filtering is needed after
that.

Starting with a square wave at some considerable power level, leaves
only expensive and impractical options.

In other words, to get there, you need to start from someplace else.

Luhan

C

#### Carl Ijames

Jan 1, 1970
0
Luhan said:
I believe my original post was essentially correct. Commercial sine
wave inverters use variable pulse width modulation to closely
approximate a sinewave. A minimul amount of filtering is needed after
that.

Starting with a square wave at some considerable power level, leaves
only expensive and impractical options.

In other words, to get there, you need to start from someplace else.

Luhan

How about the simplistic idea of just using a commercial line filter?
The original poster did not specify his power level, but Belkin and
Schaffner and Curtis (among many others) make one and two stage filters
up to 12-15A at 120V for under $50. Doesn't solve the voltage droop, of course, but sure is easy. L #### Luhan Jan 1, 1970 0 Carl said: How about the simplistic idea of just using a commercial line filter? The original poster did not specify his power level, but Belkin and Schaffner and Curtis (among many others) make one and two stage filters up to 12-15A at 120V for under$50. Doesn't solve the voltage droop, of
course, but sure is easy.

Interesting idea, but I thought those filters only removed fairly high
frequencies? That in itself may get rid of some of the 'noise' that
square wave inverters are notorious for.

Luhan

J

#### Jamie

Jan 1, 1970
0
Luhan said:
You can't get there from here.

Luhan
but you can get there from other there.

J

#### joseph2k

Jan 1, 1970
0
Joel said:
If you have a somewhat fixed load at lowish (<100W or so) power levels, you
can use a rather large inductor and capacitor to build a low-pass filter and
knock down the non-60Hz (or 50Hz) harmonics. Add more inductors and
capacitors to make the result as sine-ish as you're willing to pay for...

In the general case of high power/widely varying loads, this approach
quickly becomes more expensive than just buying a sine wave converter in the
first place and hence isn't practical... unless you're looking for an
educational in winding your own high power inductors, which actually is
rather fun...

I guess you are younger at heart than me, somewhere in the past decade i
ceased to consider winding high power inductors fun.

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