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eq1

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I was thinking about this while drinking my morning coffee and realized the peak-hold solution is way too hard. One could make the hold cap leak so the peak doesn't need to be refreshed, hence no need for a reset pulse, but the AD9837 is giving a pure sine and the THD of the VGA and power amplifier will be very low at 10s of Hz (with any part made after 2010) so the measurement of the output can be to just integrate this sine and compare that to a reference. This would provide a higher bandwidth on the control and is easier to implement. The easiest, and most accurate way, is to just buy an amplifier that measures Vrms directly. Or, rectify the output and integrate that with a time constant that's slow compared to 60Hz, not Vrms but good enough for a known pure sine. Diode drop is small compared to 120V so even that should still be a quite accurate measurement w/o much effort.eq1 said:With the AD9837 you'll get a very precise frequency and with the output peak-hold controlling the input peak into the transformer you'll get a precise output level too.