using Audio amp as a power inverter

When i made the battery coment was refering to the other circuit.

If I was to bridge these 2 amplifiers I would use a mono signal to feed both inputs of the 2 boards then connect the positive outputs of the 2 side to a speaker but wouldn't that require something to invert the input signal on one of the sides?

The output of one amplifier can feed the inverting input of the other amplifier, if you can get the schematic and parts layout.

Well that's out of the question, I can't get anything for Chinese boards that's why I always want to build my own

Enzy said:

Well that's out of the question, I can't get anything for Chinese boards that's why I always want to build my own

Click to expand...

If you "always want to build your own" then why are you picking the most inefficient method to build an inverter? You started out asking a question about using a power amp as an inverter, and now you're talking about bridged amplifiers driving a speaker. You've got me totally confused.

It should be bridge amplifer driving a transformer I probably just said speaker because audioguru did or because I'm saying amplifier so it was just a mistake

- - - Updated - - -

Also I'm still not sure why its the most inefficient way of creating an inverter

You do not need a bridge amplifier to drive a transformer. One amplifier can use a positive and negative supply or one amplifier with a single polarity supply can drive the transformer through a coupling capacitor.

An efficient inverter uses Pulse Width Modulation to make the sinewave where the output devices switch completely on (lots of current but almost no voltage so very low heating) then they switch completely off (no current so no heating) at a high frequency. The width of the pulses determines the average output voltage of the low frequency sinewave. A simple filter at the output filters away the high frequency switching. A class-D audio amplifier, DC motor speed controller and a light dimmer also use Pulse Width Modulation. Very efficient.

A linear audio amplifier (class-AB) has voltage and current in the output devices all the time so they waste almost half the power supply power making heat (very inefficient).

So do you think it's an inefficient to make an inverter using a class d amplifier method or is it better to stick to traditional methods?

It's not clear what your intention is here. Do you want to "build your own inverter"? Then, do some research on inverter circuits. Do you want to use an off-the-shelf power amplifier? A class-D amp makes way more sense than a class AB, as has been repeatedly noted here. But that still means you're trying to use something for which it was not really intended.

barry said:

It's not clear what your intention is here. Do you want to "build your own inverter"? Then, do some research on inverter circuits.

Click to expand...

You seem to only read the last message each time you come online, My intention should be very clear if you read the Title of the post even if you havent read anything thats been said.

but let me say it, the aim is to use an audio amplifier as an inverter. you asked if I want to build my own inverter that would be yes otherwise I would just purchase one.

I have been doing research on inverter circuits for years now and have made several.

- - - Updated - - -

barry said:

Do you want to use an off-the-shelf power amplifier? A class-D amp makes way more sense than a class AB, as has been repeatedly noted here. But that still means you're trying to use something for which it was not really intended.

Click to expand...

I would prefer to build my own circuit I stated that earlier in the messages but if unable to build the type I require then I would have to purchase an amplifier board/s for the purpose.

I am aware a class D amplifier makes more sence since its 90% efficient or higher and a class AB is 50% or less as was already discussed in this thread.

I am aware that an amplifier isnt intended to be used as an inverter so far no one has said that using a class D amplifier as an inverter is less efficient so I dont see any harm in trying.

- - - Updated - - -

SO on the other hand even if using a power amplifier (class D) was still less efficient than using a traditional method of making an inverter it still wouldn't stop me from trying this is my hobby after all.

I can make another post about a traditional version inverter I have many designs working on but I tend to source parts before I bring it here so I can do tests as I post to make things quicker.

A "traditional" very cheap inverter produces a squarewave output and therefore is very efficient. It powers incandescent light bulbs and heaters very well but not most electronic items that need a pure sinewave. The cheap squarewave inverter has poor voltage regulation so its output voltage drops when it is loaded. A better cheap inverter produces a "modified" sinewave which is actually a modified squarewave output which might cause noise when powering audio equipment. A properly designed PWM pure sinewave inverter or a class-D amplifier used as a pure sinewave inverter has excellent output voltage regulation.