Bipolar +/- 30 V 1 A 1 kHz sine wave amplifier - op amp, voltage controlled power supply, or ??

[Steve]

I need to amplify a sine wave (0.05 to 1 kHz) to +/- 30 Volts at 1
Amp. The output voltage needs to be adjustable and can be
accomplished by varying the input amplitude or circuit gain. I've
considered using an op amp such as the OPA548 but am wondering if
there is a bipolar power supply capable of external voltage control
with a $100 to $200 cost or an inexpensive complete amplifier or
another approach. I need two such devices for driving two coils to
generate out of phase magnetic fields.

Steve

 

[Phil Allison]

"Steve"

I need to amplify a sine wave (0.05 to 1 kHz) to +/- 30 Volts at 1
Amp. The output voltage needs to be adjustable and can be
accomplished by varying the input amplitude or circuit gain. I've
considered using an op amp such as the OPA548 but am wondering if
there is a bipolar power supply capable of external voltage control
with a $100 to $200 cost or an inexpensive complete amplifier or
another approach.

** A stereo amplifier rated at 50 watts into 8 ohms per channel could be
modified to do the job you want.

Or else find yourself an old Crown DC300A, which would be ideal.

I need two such devices for driving two coils to
generate out of phase magnetic fields.

** Those coils each have 30 ohms resistance with no iron cores - right ?




..... Phil

 

[Jamie]

I need to amplify a sine wave (0.05 to 1 kHz) to +/- 30 Volts at 1
Amp. The output voltage needs to be adjustable and can be
accomplished by varying the input amplitude or circuit gain. I've
considered using an op amp such as the OPA548 but am wondering if
there is a bipolar power supply capable of external voltage control
with a $100 to $200 cost or an inexpensive complete amplifier or
another approach. I need two such devices for driving two coils to
generate out of phase magnetic fields.

Steve

You may want to look at another OP-AMP, spec's indicate that it's
60V supply which means a +/- 30V for what you want. Also, spec's
indicate that you lose ~ 2.0 volts at 1 AMP out from the rails.
if you're truly looking for that +/- 30V's on the output, this
could be a problem.

Unless you plan on bridging them ?




http://webpages.charter.net/jamie_5"

 

[Joerg]

I need to amplify a sine wave (0.05 to 1 kHz) to +/- 30 Volts at 1
Amp. The output voltage needs to be adjustable and can be
accomplished by varying the input amplitude or circuit gain. I've
considered using an op amp such as the OPA548 but am wondering if
there is a bipolar power supply capable of external voltage control
with a $100 to $200 cost or an inexpensive complete amplifier or
another approach. I need two such devices for driving two coils to
generate out of phase magnetic fields.

As others have pointed out, plenty of stereo amps can be had cheaply at
garage sales and many can be reworked to operate near DC. If everything
else fails something like this ought to do:

http://cache.national.com/ds/LM/LME49810.pdf

 

[Joerg]

Naaah! Just take any old OpAmp and add a discrete device output
stage... take maybe 5X gain in the output stage, and it'll be easy to
make ±30V at 1A.

Nah, then do it the modern way. I'd probably go class D on this one

 

[neon]

It is amazing that you get replys. 1 amp out from where microvolts input? you got the freq. but no input.LM144 can get you +/-30 v0lts swing from +/-36v rail.the current out is another thing i guess an LM195 and a current source as LM117 might do it. of course lm3876 56w can do the whole thing.anyhow look into LM38xx series. good luck.