Audio amplifier as AC power generator ?

"Robert Lacoste"

** You *can* make it work - but there are some serious provisos. As a rule, audio power amplifiers ABHOR driving a ( step-up) transformer.

If you do not clearly understand transformer core saturation issues or the "inrush surge " phenomenon - that poor eBay power amp is not gonna last too long with you.

Here is a tip - try using a 4 ohm, 100 watt resistor in series from the amp output to the transformer.

Gives the amp a fighting chance ...

...... Phil

you also need to consider that while the amp might be able to produce the

50-60 hertz just fine, the "glitches etc" represent a very high frequency component that could be outside the cheapo amp's range.

"no_one"

** What a hoot !!

no_one = another know NOTHING !!!

ROTFLMAO !!

...... Phil

"Phil Allison" a écrit dans le message de news: snipped-for-privacy@mid.individual.net...

Thanks Phil, effectively I had in mind to start with a serial resistor just in case... I will then follow your recommandation. Regarding transformer I think that using an overrated transformer should help to limit the saturation issues. The good news is that as my ebay power amplifier is stereo I will have a second chance is something goes wrong on the amplifier channel I will be using ;+)

PS : Regarding glitches of course they must be in the passband of the amplifier as "no_one" said, but this shouldn't be a limiting factor for all non-EMI related requirements (like loss of power for a couple of cycles, voltage dips, etc).

Anyone who will have actually tested such an arangement ?

Robert.

We have a Peavey 400-watt per channel PA amp. We have a precision home-made 2-phase sinewave generator that drives the amp, with selectable phase angles. One amp output drives a step-up transformer to give us 0-500 volts RMS. The other drives a step-down transformer to make 0-200 amps into low impedance loads, namely current transformers and shunts. We use this setup for development and calibration of electronic wattmeters.

Works fine. We did change some caps in the amp to extend low frequency response, to reduce phase shift at 50/60 Hz. If the amp has loudness control or any sort of auto level control, kill them.

John

Back in my MIT school-days, I used a pair of 400-watt home-brew to-o-o-ob amplifiers to drive a smear camera motor ;-)

...Jim Thompson

--
|  James E.Thompson, P.E.                           |    mens     |
|  Analog Innovations, Inc.                         |     et      |
|  Analog/Mixed-Signal ASIC\'s and Discrete Systems  |    manus    |
|  Phoenix, Arizona            Voice:(480)460-2350  |             |
|  E-mail Address at Website     Fax:(480)460-2142  |  Brass Rat  |
|       http://www.analog-innovations.com           |    1962     |
             
         America: Land of the Free, Because of the Brave

"Jim Thompson" wrote in message news: snipped-for-privacy@4ax.com...

400 watts? Dats a big toooooob (or a lot of little ones?)!

Bob

Trying to remember now, after around 48 years... 5881's, KTxx's or

8550's (so many to-o-o-obs, so little memory left :-), home-wound output and power transformers (laminated-iron C-cores held together with hose clamps :-).

...Jim Thompson

--
|  James E.Thompson, P.E.                           |    mens     |
|  Analog Innovations, Inc.                         |     et      |
|  Analog/Mixed-Signal ASIC\'s and Discrete Systems  |    manus    |
|  Phoenix, Arizona            Voice:(480)460-2350  |             |
|  E-mail Address at Website     Fax:(480)460-2142  |  Brass Rat  |
|       http://www.analog-innovations.com           |    1962     |
             
         America: Land of the Free, Because of the Brave

Thanks John !

"John Larkin" a écrit dans le message de news: snipped-for-privacy@4ax.com...

Interesting, I have 2, 800 Watt RMS Carvin amps sitting around doing nothing.. Sounds like an interesting application.

"

"Robert Lacoste" "Phil Allison"

** OK - now I see you have NO idea what saturation or inrush surges in a AC supply transformer even are.

Cos the bigger they are, the worse the problem gets.

** Complete idiocy.

** I am very familiar with audio power amps being used to drive step up transformers.

Even with music and speech applications, it is just an accident waiting to happen.

With YOUR idea - there will be no need for waiting.

....... Phil

"John Farkin Lunatic "

** Shame there is no comparison with the OP's loopy idea.

No saturation or inrush surge issues with your set up - is there ?

...... Phil

Haven't seen any. The ole Peavey is a tough mamma. When I told them what I wanted to do, they sent me a schematic right away and suggested which coupling caps to change. Real Southern gentlemen.

John

"John Farkin Lunatic "

** Then shut the f*ck up - you pathetic, autistic MORON .

...... Phil

Sounds good to me You are looking at 100w rms continuous.

Bob

"sycochkn"

** ROTFL !!

If ignorance is bliss, this dude is in heaven.

....... Phil

I was answering your question. You really are in a foul mood lately. [1]

John

[1] "lately" measured in decades. You are in mortal danger of spending the rest of your life being Phil.

"John Farkin Lunatic "

** Without the slightest damn idea what it was about.

Shut the f*ck up - you pathetic, autistic MORON .

..... Phil

I've sold about $1.4 million worth of gear developed and tested on this rig. Do I have to give the money back?

John