Why not an H-bridge?

[Stocker]

You have all sorts of benefits with only slightly increased cct complexity...why not make an H-bridge out of a gainclone? You wouldn't even need all the output transistors.

[peranders]

Can you explain exactly what you mean?

[Stocker]

This:



One side non-inverting with or without gain. The other side an
inverting follower. Both outputs tied to the speaker terminals.

[leadbelly]

Nothing new. Search on "BridgeClone" and see how many hits you get.

[Stocker]

aahhhh... will do...

I haven't seen such a beast mentioned here in months, and didn't know the term. Muchas gracias.

[macboy]

This is not recommended for National's chipamps, but it will work for Burr Brown OPA5xx's. The reason is that all of National's chipamps require a gain of 10 or higher to be stable. Since the 2nd chipamp in the circuit is a unity gain follower (gain -1), it will be extremely likely to be unstable and to oscillate. It's a better idea to just bridge in the normal manner with both amps fed from the same input, rather than having the second one fed from the output of the first one.

[Stocker]

It is my understanding that unity gain is not a problem with National's chipamps in *inverting* configurations; non-inverting is where the problems come in with unity gain...

Can anybody confirm or refute?

[analog_sa]

It is my understanding that unity gain is not a problem with National's chipamps in *inverting* configurations; non-inverting is where the problems come in with unity gain...

Jesus loves you.

Not true. Dunno about Jesus either...

[Stocker]

Originally posted by analog_sa

The only way to get gain around unity from these chips is to use inverting topology.


cheers

peter

ahem.

and in the same thread I find:

Kuei Yang Wang posts:

...You CANNOT get unity gain in non-inverting topology, you can extremely easily get unity gain in inverting mode. Simply use a pair of 220k Resistors, one from the Amp input to the inverting input, the other from the inverting input to the Output. (snip) ...Unity gain and stable. Easy as pie.

and

JAZZ2250 has some PROOF:

Thanks to Kuei Yang Wang, prototype gainclone with unity gain is finally working. The chip doesn't get hot at all. Like he wrote, it's almost magic to me.

and Nielsio has some PROOF:

I first built the original inverted Thorsten schematic, and had some hum and noise (especially when volume was 0 or max); now I've changed it like Kuei suggests (pic). And also, as was predicted, it's now 'dead quiet'. 0 hum and 0 noise.

's wonderful..

~~~~~~~~~~~

Gee, I wonder where I might have got the idea that unity gain was possible...

maybe here?
http://www.diyaudio.com/forums/showthread.php?s=&threadid=9852&highlight=unstable +unity+gain

[macboy]

Stocker,
This unity-gain business is news to me, but very nice to know. Thanks.