Xmfr drive lo res load

[K. Donovan]

This thing is driving me nuts. I have a TA2009 audio amp module. I
want it to drive a PA type step-up transformer for voltage gain. IOW
around 200V out. The signal is a 60Hz sinewave. The secondary is to be
connected across a negligible load resistance, eg. wide area coil of
few turns. But when I connect the latter, it kills the signal both
sides of the xfmr.

Is there a right way to drive this coil via a xfmr or am I dreaming?

The module only does around 10W. Is this the problem? But I have tried
adding 8 ohm resistors all over the place with no result.

Ken Donovan

 

[Phil Allison]

"K. Donovan"

This thing is driving me nuts. I have a TA2009 audio amp module. I
want it to drive a PA type step-up transformer for voltage gain. IOW
around 200V out. The signal is a 60Hz sinewave. The secondary is to be
connected across a negligible load resistance, eg. wide area coil of
few turns. But when I connect the latter, it kills the signal both
sides of the xfmr.

** Why the heck are you surprised ?

What you are attempting is very silly indeed.

Is there a right way to drive this coil via a xfmr or am I dreaming?

The module only does around 10W. Is this the problem? But I have tried
adding 8 ohm resistors all over the place with no result.

** Errrr - when you want to drive a load impedance that is LOWER than
normal for an amplifier, the idea is to use STEP DOWN transformer.

Cos that will increase the available current while reducing the voltage by
the same ratio.

Capice ?



......... Phil

 

[Tom Bruhns]

This thing is driving me nuts. I have a TA2009 audio amp module. I
want it to drive a PA type step-up transformer for voltage gain. IOW
around 200V out. The signal is a 60Hz sinewave. The secondary is to be
connected across a negligible load resistance, eg. wide area coil of
few turns. But when I connect the latter, it kills the signal both
sides of the xfmr.

Is there a right way to drive this coil via a xfmr or am I dreaming?

The module only does around 10W. Is this the problem? But I have tried
adding 8 ohm resistors all over the place with no result.

Ken Donovan

Since it's 60Hz, you could try just plugging it into a mains outlet
and see what happens. Likely, you'll blow a breaker; if not, the coil
will probably get very hot. Current equals voltage divided by
impedance. The impedance is probably quite low, a few ohms at most,
unless the coil is really large, several square meters area and quite
a few turns. Power dissipation equals square of current times
resistance. Note that an 8 ohm resistor across 200 volts will
dissipate (for a short time, at least) 5000 watts.

Just what is it that you are trying to accomplish?

Cheers,
Tom