My latest assignment requires me to evaluate a power supply design that ope rates off of 400Hz ac power. To validate the design I have to apply lots o f signal fluctuations. These fluctuations include frequency sweeps and var ious voltage ramps up and down. Abrupt frequency changes are also required . Most of these waveforms are not available on function generators and are not even realizable on arbitrary waveform generators (at least I could not figure out how to easily create them)
I have a gradient amplifier which is a high power op amp that is DC coupled . It turns out this is a high powered audio amp that is dc coupled (it was made by crown audio and relabeled by picker ). After rethinking this prob lem I have come to think of it as driving the unit with high power audio.
As an aside, the audio amp cannot achieve the voltages I need , but I have found a 150W transformer (2.5:1) that is good at the frequencies I need.
Anyhow, I have matlab with simulink and using I/Q modulation against a fre eruning audio source I can run my base frequency and apply various signal t ransformations and create nearly every specified waveform. I then play the m out of the audio port of the computer and into a simple op amp then to my gradient amplifier.
I ran into one small problem....my audio output was not good. There was pr obably 3dB of variation in a sweep from 400-800 Hz. On a lark, I bought on e of these for 10$:
And guess what.... flat as a pancake. Absolutely perfect response (at leas e where I need it).
You can use matlab and simulink as a very powerful laboratory waveform gene rator.