Continue to Site

Welcome to our site!

Electro Tech is an online community (with over 170,000 members) who enjoy talking about and building electronic circuits, projects and gadgets. To participate you need to register. Registration is free. Click here to register now.

  • Welcome to our site! Electro Tech is an online community (with over 170,000 members) who enjoy talking about and building electronic circuits, projects and gadgets. To participate you need to register. Registration is free. Click here to register now.

Square wave current output to sine wave

Status
Not open for further replies.

reservoirdog

New Member
Hi guys, this is my first post. It is something I require for a practical reason.

I bought a UPS that I found out, quite unfortunately, outputs square wave current. This does not sit well with my adapters (WiFi, modem, etc.) and I have to routinely buy new ones.

So I was wondering if I could juryrig a converter that'll convert the square wave output to sine wave. That way I won't have to buy a new UPS.
 
what are the output details? You can take a look at this:
**broken link removed**

the capacitance and inductance values determine the smoothing of the square wave output from the 555 timer, you can try that.
 
Of course a low pass / band pass filter would smooth the square wave.

BUT... How would you amplify the sine wave without major issues? Think about it, a 500VA UPS would need a amp. with, lets say, 400W RMS output.
 
A square wave requires only switching. A sine wave requires amplifiers operating in the linear region, it is harder to design and more expensive. A filter is low power. You have to filter a square wave to get a sine and then amplify it.
 
You could use an LC filter to filter the output, but the parts would be large. To resonate at 60Hz requires a 50µf non-polarized capacitor and a 140mH inductor, for example.
 
Last edited:
The inductor would just be bulky. The capacitor might be a problem as it'd have to be highly over engineered to sustain ripple current for any serious power.
 
The inductor would just be bulky. The capacitor might be a problem as it'd have to be highly over engineered to sustain ripple current for any serious power.
The capacitor should probably be an oil-filled film capacitor such as they use for AC induction motor run (not start) applications.
 
A sine-wave inverter uses a high frequency DC to DC high voltage output converter using a small ferrite high frequency transformer then uses Pulse-Width-Modulation to construct a 50Hz or 60Hz modulated sine-wave that has the high frequencies filltered out with a little ferrite LC filter.
It does not use a linear amplifier that wastes a lot of power getting very hot.

A square-wave inverter has half of its output power in its harmonics so if it is filtered somehow (a filter will waste a lot of power) then its output voltage will be 0.707 times too low without counting the loss from the filter.
 
when you pass it through a transformer of bit higher rating, you may probebly end up with some good out put, but there will be a big power waste in the transformer.
 
Status
Not open for further replies.

Latest threads

New Articles From Microcontroller Tips

Back
Top