TDA2030 inverting input

"exxos" schreef in bericht news:40ce0447$0$20516$ snipped-for-privacy@news-text.dial.pipex.com...

will

Chris,

Even without looking at the datasheet, I'd say that you cannot simply swap inverting and non-inverting inputs. Even with simple opamps you'll have to modify the circuit to change an inverting amplifier to a non-inverting one. Not to speak about the change of the other properties of the amplifier. A quick look at the TDA2030 datasheet gives the impression that it is not meant to be used as an inverting amplifier. To check it out you may study the datasheet carefully and(try to) design the amplifier you want.

BTW why do you want to invert an audio signal?

petrus bitbyter

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and

bit

?

one.

I want to bridge the inputs of 2 amps, though I dont want to do it the way the datasheet does it, the datasheet seems to use the speaker output of 1 amp to drive the input of the second amp, this is insane. I have designed a phase splitter with a simple transistor, though this works great I have a

5volt DC offset somewhere, so the speaker cone is pulled back slightly, nevertheless it works great, im trying to find other ways to bridge the amp since my circuit don;t seem to be working correctly. Ive tried to use a small preamp IC as a inverting and non-inverting X1 "buffer" though I cant get this to work for some odd reason :(

Chris

On Tue, 15 Jun 2004 21:32:59 +0100, "exxos" wrote: snip

If you are refering to that circuit on page 6/11 of ST's datasheet

it looks to me like a typical bridge amplifier, cant see much weirdness about it. Do you not think that perhaps ST know what they are doing. There's a lot to be said for following reference desings.

Kev.

The left of that circuit is non-inverting, the right side is inverting.

The right side could in principle be connected to the signal input instead of the output of the left stage (left side of R5), but R5 would have to be lowered to 680 ohm in that case (same as R2) - and 680 ohm is too low as input impedance.

Thomas

way

a

amp

cant

Theres always room for variations on designs. I personally dont like the way that there is only 1 input then the second input is inverted from the speaker output and feed back into the second amp, does that make sence ? In anycase all the "rubbish" comming from the speaker is whats been feed back into the amp, it might be just me though im not happy with that, everyone does it , but dont mean its the better idea. I like to try some variations on things, I am sure driving both amps from the same source is a much better, though what do I know...

Chris

The TDA2030 in teh design has quite low impoedance paths around it. You could use another amp as a driver stage - that would be no problem.

But I think that is low distortion is the goal, a bridge is not the best idea.

Thomas

way

In

back

everyone

variations

im trying to use a small X1 preamp chip to invert the wave, though not had much luck so far, I know there will be greater crossover distortions, though I would still prefer to do it this way.

Chris

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swap

to

A

study

a

amp

Looking at the datasheet I found the right part of that bridge amplifier almost the inverting amplifier you ask for. It amplifies the output of the left amplifier by minus one. You can disconnect its input by disconnecting the 22k resistor R5 from the output of the left amplifier. You can use this as the input of your inverting amplifier by connecting it to the input of the left amplifier. But... it dus not amplify, it only inverts the input voltage. To make the amplifier you want, you have to lower the 22k resistor to 680 Ohm. This makes a very low input impedance and I think your signal source doesn't like that. To overcome this problem, you can use an emitterfollower for impedance matching. It's worth to experiment but you can't be sure beforehand that it'll work the way you want it to do.

petrus bitbyter

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